Hi all. I wanna thank everyone for their help on the long thread that helped me sort out power, sound, re-wiring et al on this TV. I now have a good picture with very good resolution and sound coming out of a speaker. I'd like to learn something about alignments, fed signals, scope traces, sweep and the like. I thought I would start simple with the discriminator and sound IF alignment. Below is the instruction section in the Rider's service manual for this:

https://imagizer.imageshack.com/v2/1024x768q70/922/3TRo7H.jpg

...and some traces and transformer location figures

https://imagizer.imageshack.com/v2/1024x768q70/922/PrNajS.jpg

https://imagizer.imageshack.com/v2/1024x768q70/923/tfbqC0.jpg

For those who have participated in helpful discussions before, you probably know what my level of experience is. I can talk some of the talk but there are some significant gaps there. I usually get over my embarrassment fairly quickly but please, be gentle!!!

Over the next few days, I hope to move through the VTVM and scope trace steps in this protocol. Ten fifteen pm on the east coast so tomorrow evening I'll begin. I have done a couple of min/max adjustments using the VTVM before so hopefully, I'll get off to a good start! TIA for the help!

Good luck. I suggest you also take a look at the Sams instructions. Thye often use language that makes more sense.

Hi and happy aligning. I have had experience successfully aligning this chassis for more than 50 years. It can be a challenge if you do not keep various factors in mind.

First you must have accurate marker frequencies. This is a split sound set and to achieve optimum picture quality with best sound, the marker accuracy is utmost. I use an HP5245L frequency counter with an HP 606B signal generator. Plus my favorite alignment combo is the HP8601a Sweep generator with HP8600 Digital Marker. The total net cost for all of this equipment combined was $150 and it was top of the line. There are many solutions available and all are now pretty cheap. It would be wise to review what equipment you have before you begin. Remember this set has more trap circuits than any other set! Two adjacent sound, two adjacent video, two co-channel sound, a baseband trap and an RF trap, each if misadjusted can adversely affect the video quality.

Second as this is a split sound receiver, the fine tuning control is adjusted for best sound, not best picture. If the alignment is not correct, when fine tune for best sound, the video will not look good. So it is essential as the manual advises to first proceed with the sound IF and descriminator alignment before proceeding with the video alignment.

Third, be aware the quality of the video IF amplifier tubes will affect the end result. Make sure you have fresh tubes in place you can trust. Because changing a tube in the video IF will affect the response curve.

Lastly before you start, the set uses an over coupled transformer between the tuner and first video IF stage. This is a broadly coupled link and it is essential to sweep align it. You must follow the instructions in the manual to get the curve depicted. I found it pointless to proceed unless I can get the proper response at this point because the subsequent video IF sweep adjustment will not be right.

I would suggest following the step by step process to the letter and if/when you reach a stumbling block, simply post it on the forum.

Yeah, you picked a very hard one as your first attempt for IF alignment, a real pain!

And as mentioned above, the way pointed out in the SAMS often makes more sense, it worked for me with the ARVIN, using a RF frequency generator and a meter to set the coils, I do not have a sweep marker generator, so I was not able to do the final overall IF alignment step, but as I said before, of all my BW sets, the ARVIN is the only one that gets snow W/O anything hooked to it, so I must have got it rather close to right!:D

Hi and happy aligning. I have had experience successfully aligning this chassis for more than 50 years. It can be a challenge if you do not keep various factors in mind.

First you must have accurate marker frequencies. This is a split sound set and to achieve optimum picture quality with best sound, the marker accuracy is utmost. I use an HP5245L frequency counter with an HP 606B signal generator. Plus my favorite alignment combo is the HP8601a Sweep generator with HP8600 Digital Marker. The total net cost for all of this equipment combined was $150 and it was top of the line. There are many solutions available and all are now pretty cheap. It would be wise to review what equipment you have before you begin. Remember this set has more trap circuits than any other set! Two adjacent sound, two adjacent video, two co-channel sound, a baseband trap and an RF trap, each if misadjusted can adversely affect the video quality.

Second as this is a split sound receiver, the fine tuning control is adjusted for best sound, not best picture. If the alignment is not correct, when fine tune for best sound, the video will not look good. So it is essential as the manual advises to first proceed with the sound IF and descriminator alignment before proceeding with the video alignment.

Third, be aware the quality of the video IF amplifier tubes will affect the end result. Make sure you have fresh tubes in place you can trust. Because changing a tube in the video IF will affect the response curve.

Lastly before you start, the set uses an over coupled transformer between the tuner and first video IF stage. This is a broadly coupled link and it is essential to sweep align it. You must follow the instructions in the manual to get the curve depicted. I found it pointless to proceed unless I can get the proper response at this point because the subsequent video IF sweep adjustment will not be right.

I would suggest following the step by step process to the letter and if/when you reach a stumbling block, simply post it on the forum.

Thank you so much for all of that information. I was looking at the HP606B generators on eBay but since they are analog, I thought they probably wouldn't be stable enough. At this stage, I'm probably going to need to purchase better equipment to do this right, at least from the generator/sweep end. I have a modern digital scope purchased last year and an HP scope that's about 30 years old both of which will do X-Y traces and are very accurate. I might try the Eico 369 I have just for practice until I can get better equipment. I'd be thrilled just to see a trace similar to the sound IF curve depicted. I have all NOS tubes in the TV

I'd like to treat this as an education journey and not a means to an end to get this particular TV perfectly aligned. How to feed in signals...set up scopes...interpret what changes in response curves mean etc... Other than adjusting coils for peak or minimum response on a VTVM is about all I have done in this realm! Believe me, I will ask questions but some of them may elicit an initial reaction of "He said what?...You're kidding me?"!!!!!

Good luck. I suggest you also take a look at the Sams instructions. Thye often use language that makes more sense.

Thanks Bob...I do have both.

Does anyone have a suggestion for an accurate but affordable frequency generator? A working HP 606B generator goes for more than $300 on eBay. Sweep generators used during this TV's era, like the Hickock I had that was electromechanical (and had a destroyed speaker cone inside)...were they accurate like these modern digital equivalents? I thought getting and meticulously restoring the Eico, which is early 1980s technology, and getting new, custom built cables for RF out, demod in and scope out would have been more than accurate enough to align a TV from 1948. Am I missing something here? Like I posted in the other thread, I measured the RF frequency out of the Eico using the HP oscilloscope. It varied about 0.08 megacycles plus/minus around the intended frequency. Is using an oscilloscope in this manner an acceptable way to check the accuracy and stability of an RF generator?

Extremely accurate test gear is not so important in alignment EXCEPT for accurate frequency marks. Most of the alignment steps will be to peak or null the response at a certain frequency, or make two peaks of a double-peaked curve the same height, or make a particular marker 50% of the peak, for example. So accurate actual height of the curve is mostly irrelevant as long as you get the specified shape vs. frequency.

The touchiest part of the procedure often involves the signal injection cable/circuit, the ground point, length of leads, etc.

Extremely accurate test gear is not so important in alignment EXCEPT for accurate frequency marks. Most of the alignment steps will be to peak or null the response at a certain frequency, or make two peaks of a double-peaked curve the same height, or make a particular marker 50% of the peak, for example. So accurate actual height of the curve is mostly irrelevant as long as you get the specified shape vs. frequency.

The touchiest part of the procedure often involves the signal injection cable/circuit, the ground point, length of leads, etc.

The Eico does have a variable marker frequency dial with adjustable amplitude but, I can't possibly know if a marker frequency selected on a crudely numbered dial scale is correct. My B&K alignment generator has all of the markers pre set and ready to go...for TVs aligned using frequencies around 20 mc higher.

Are referring to the B&K 415? It only has markers for 44MHz IFs.

The Eico does have a variable marker frequency dial with adjustable amplitude but, I can't possibly know if a marker frequency selected on a crudely numbered dial scale is correct. My B&K alignment generator has all of the markers pre set and ready to go...for TVs aligned using frequencies around 20 mc higher.

Does your digital oscilloscope have a frequency read out? :scratch2:

jr

Yes

Are referring to the B&K 415? It only has markers for 44MHz IFs.

B and K 1077

1077 is not an alignment generator or fixed frequency RF generator - it only outputs test patterns. Composite or RF modulated video.

A basic grounding in superhet theory is a good starting point, along with knowing why stagger-tuning of the IFs is necessary in TV receivers.

1077 is not an alignment generator or fixed frequency RF generator - it only outputs test patterns. Composite or RF modulated video.

Yes yes yes yes yes....I shouldn't talk about these things without them in front of me...I meant the 415...I have them both.

1077 is not an alignment generator or fixed frequency RF generator - it only outputs test patterns. Composite or RF modulated video.

+1 the 1077 is for figuring out WHY your IF is dead, not for alignment....It's also good for signal injection troubleshooting on every other circuit in a TV (which is why I like mine it helps me fix dead sets faster).

I bought my HP 606B locally thru Facebook Marketplace for $35. It required some repair. But to obtain the accuracy with it or any other marker source, you will require a frequency counter.

Decent sweep generators are easy to find cheaply. Coupling the equipment should be straight forward if you follow the procedure outlined.

You will be able to get the responses depicted only if you have the proper equipment and you can trust your frequency source.

And I only ended up with the HP606B because it was cheap and available. I have have three different HP frequency counters which I obtained over time because they happened to be cheap and were readily available. I believe we live in a fortunate time where so much 1960s and 1970s test equipment which we once could only dream of are now available for next to nothing.

What have you to measure the frequency source accurately?

I want to reluctantly add that I have not be averse to dumpster diving. A local community college was throwing away Wavetek sweep marker generators. The cords were cut off and a few toggle switches were faulty. All easily fixed and it was free. I earlier used an old Precision generator made in Elmhurst NY which I got for free. It needed a few repairs but it worked well. The venerable HP5245L I bought for $25 with a few minor faults. The best addition I made to it was to replace the noisy original fan with a quiet modern computer fan.

I would suggest you first present here your equipment choices and we can provide advice.

Hi all...just a couple of things and questions.

I did the first two steps in the alignment that required the use of the VTVM and I think I was successful.

So yes Penthode, I will detail a list of the equipment I have. Below is what I bought, restored and thought would provide the entire package for doing these alignments.

https://imagizer.imageshack.com/v2/1024x768q70/923/TwPh0Q.jpg

The way I understood this worked was the RF frequency out is selected using the dial on the right. You select signal strength with the attenuator dials. Sweep width is selected using the sweep dial. Maximum range on this is 10 megacycles. The signal is fed into the desired point(s) on the chassis. If the signal out requires demodulation, it comes back in from the desired point in the circuit using the demodulation cable back into the 369. At that point, a marker is added to the trace selected by the dial on the left and the marker size is adjustable. The processed signal comes out and goes to the scope by the scope out jack which is a funky, special jack that essentially provides a horizontal, vertical and ground signal interpreted on a scope using X-Y mode.

Here are my oscilloscopes...an HP 54600B and a Chinese scope...works well and cost a little over $200 (not that it indicates anything. It was well reviewed)

https://imagizer.imageshack.com/v2/1024x768q70/922/sPzKEH.jpg

https://imagizer.imageshack.com/v2/1024x768q70/924/deULRa.jpg

That's what I got! I don't have a frequency counter or a separate RF generator and sweep generator. I think I have a shelf full of equipment that needs to be scrapped and I'll have to start from scratch! :no::no::tears::tears::tears::tears:


Some of this has already been done but if my friends can provide some shopping lists and maybe some information on how all of them work together it would be appreciated. I think, at this point, I don't have what I need to dive into the more detailed and intricate steps in this process.

I see the Eico sweeper marker generator has a crystal in it. What is it's resonant frequency?

The marker frequencies for the traps were 19.75, 21.25 and 27.25MHz. The bandpass markers that are most important are 22.1, 24.5 and 25.75MHz. The Eico could use the one or perhaps two or three crystals to calibrate it's variable frequency generator.

A cheap shortwave receiver with digital readout could be used to calibrate the marker. The marker accuracy needs to be roughly +/-10kHz particularly with the sound IF and sound traps vs the video carrier 45% position on the slope of the video IF response. The 27.25MHz traps must be fairly accurately set as they will affect the overall IF response. The 19.75MHz traps accuracy is least important.

Historical sidenote affecting the design of the 1948 thru 1952 receivers. This was the time of the TV station construction freeze. 1948 coincided with the sunspot peak and it played havoc with RF reception. Co-channel and adjacent channel interference between stations beyond the RF horizon created headaches for FCC planners. The double upper and lower adjacent channel traps were RCA's answer to alleviate the problem at the time. I recall the summer of 1972 the interference with another sunspot peak. From Toronto Canada reception, KMOX channel 4 in St Louis totally obliterated WBEN channel 4 Buffalo. KDKA channel 2 Pittsburgh would override EGR channel 2 Buffalo. I had an RCA 8T243 (the same chassis as yours which I still have more than 50 years later) and it worked better in these summers than many newer sets. Having more traps was a brilliant idea but it makes alignment more difficult.

It’s a 4.5 mc. I have some pictures of pages from the user manual I can post in a bit

For your reading enjoyment... Actually, I don't expect anyone to read all of this. My only hope is I can somehow use this piece of equipment to do some of the things, starting with the audio IF, I can do to optimize it's function.

https://imagizer.imageshack.com/v2/1024x768q70/924/7Rp8nE.jpg

https://imagizer.imageshack.com/v2/1024x768q70/923/yUjVAi.jpg

https://imagizer.imageshack.com/v2/1024x768q70/923/SKtnGn.jpg

https://imagizer.imageshack.com/v2/1024x768q70/922/7g6ayi.jpg

https://imagizer.imageshack.com/v2/1024x768q70/922/ZMVGTD.jpg

https://imagizer.imageshack.com/v2/1024x768q70/924/KcoJgi.jpg

https://imagizer.imageshack.com/v2/1024x768q70/923/vs445B.jpg

https://imagizer.imageshack.com/v2/1024x768q70/923/NmhaFB.jpg

https://imagizer.imageshack.com/v2/1024x768q70/924/BjOALx.jpg

https://imagizer.imageshack.com/v2/1024x768q70/924/2WTiZ9.jpg

https://imagizer.imageshack.com/v2/1024x768q70/924/4b7GX9.jpg

https://imagizer.imageshack.com/v2/1024x768q70/924/WNYqxD.jpg

https://imagizer.imageshack.com/v2/1024x768q70/924/qa7RPK.jpg

https://imagizer.imageshack.com/v2/1024x768q70/922/52XZXq.jpg

[img]

I skimmed through the instructions and it is pretty standard stuff. The 4.5MHz crystal was intended mainly for later intercarrier sets which this is not. It has little use in this alignment other than perhaps using a harmonic as a reference to set the variable marker frequency. I have to emphasize that a split sound set alignment, especially this chassis, is somewhat more complicated than the average intercarrier set and an accurate marker is essential.

The 4.5MHz crystal oscillator has a useful 5th harmonic at 22.5MHz and 6th harmonic at 27.0 MHz. These would be useful as a reference for calibrating the variable marker.

The bottom line is that you can use the Eico but it is going to be more difficult to use that a more modern set up. Good equipment is relatively cheap. My first suggestion would be try the Eico sweeper and find a separate RF generator and a frequency counter to obtain an accurate marker. A separate marker oscillator can be loosely coupled. You can also use the separate accurate marker to calibrate the Eico marker.

For my IF alignment the HP 8600a Digital Marker with the HP 8601a Sweeper is one of the best setups. The equipment dates from the 60's and 70's and provides five accurate bandpass markers. I bought them twenty years ago for about $40 each on eBay. The HP8601a is common: there are about six on eBay at the moment but the lowest price is about $165. The HP8600a was it's companion and is to integrated with the HP8601a for accurate markers and spot frequencies.

The pair of HP devices essentially is an RF Network Analyser. I do not know how much you are into electronics but a more modern and efficient approach (and cheaper too) is to you to use a modern RF network analysis tool. I see Chinese built ones on eBay for under $50 and with client software on a computer I would see this as a very accurate and spiffy way to align your set. I have for the last decade seen the cost drop and performance improve. I haven't tried this solution out myself but you should be able to see the trap notches and IF and tuner RF responses very clearly and accurately with this device. This thread has kindled my interest to finally buy one these things to try out in the application.
https://www.ebay.com/itm/126284122318

Here is another nifty one with a display. You should be able to see the IF response and accurately set the traps with one of these. I haven't tried it yet. But rather than using old clunky equipment, this may be the most efficient and yet least costly way to go.

https://www.amazon.com/Portable-TinySA-Spectrum-Frequency-Generator/dp/B08FB5XT7B/ref=mp_s_a_1_4?crid=2ESZNGK1DMFZY&dib=eyJ2IjoiMSJ9.8RCnu_nU9mxOKJPZ-iAjmmIKbW0zb14HvsTS4C3ArMHTqUnli41kkx6ylO3Ars1clxy UGcDRr2PTIW7nENbw6cnaRlNRfAVI5G7azyWi8lY.EupwwnUUh g8r2jyCoBj0yoN2fhUUVgWNPiYz1aEd4M0&dib_tag=se&keywords=network+analyser+tracking+generator&qid=1723346998&sprefix=%2Caps%2C241&sr=8-4

Here is another nifty one with a display. You should be able to see the IF response and accurately set the traps with one of these. I haven't tried it yet. But rather than using old clunky equipment, this may be the most efficient and yet least costly way to go.

https://www.amazon.com/Portable-TinySA-Spectrum-Frequency-Generator/dp/B08FB5XT7B/ref=mp_s_a_1_4?crid=2ESZNGK1DMFZY&dib=eyJ2IjoiMSJ9.8RCnu_nU9mxOKJPZ-iAjmmIKbW0zb14HvsTS4C3ArMHTqUnli41kkx6ylO3Ars1clxy UGcDRr2PTIW7nENbw6cnaRlNRfAVI5G7azyWi8lY.EupwwnUUh g8r2jyCoBj0yoN2fhUUVgWNPiYz1aEd4M0&dib_tag=se&keywords=network+analyser+tracking+generator&qid=1723346998&sprefix=%2Caps%2C241&sr=8-4

I bought it. Maybe when it gets here we can take a shot at doing this together?

The second one, does it have a tracking generator? The first one which was cheaper has a tracking generator. The tracking generator feeds the network under test ( in this case the RF/IF section of the TV).
The second unit has also two connectors. But is one the tracking generator output?

What is required is a network analyser and not just the spectrum analyser. Need to find more information on the product.

I made a video on using the TinySA as a sweep gen for TV alignment. I think you'll find it useful.
https://youtu.be/BQJjgpHyWRs

Looks like it can be used in conjunction with a separate tracking generator

It is the tracking generator. I think you mean marker generator. Yes, you can loosely couple a second generator to create a marker blip

So I was thinking about this last night and couldn't sleep! Not exactly what a relaxing hobby should do for you! If I could get your thoughts on this, Bob and Penthode and anyone else who would like to contribute ideas, here is what I'd like to do...

I want to find the optimal method and equipment to do alignments on TVs from this era. I'm a bit tired of purchasing vintage equipment in an effort to do this. It seems to always be compromised by inaccuracy and reliability issues.

I was looking at these network analyzers last night and they run the range from bare bones circuit board setups to ridiculously high priced units. I would be willing to spend several hundred dollars on a modern alignment package and go through the process of aligning the RCA with anyone who would be willing to walk through it with me. I could document the process with photos and post a protocol start to finish here on VK. Maybe it could be helpful to others who have had similar struggles with this. I have a shelf full of vintage test equipment purchased with the intent of aligning these TVs that have led to frustration and getting nowhere.

So the path could look like this...I will purchase whatever is needed to do this in the optimal and simplest way with the desired outcome being a workbench decluttered of useless vintage test equipment replaced by a modern and reliable alignment station I can go to with confidence. Hopefully someone could walk through this with me and in doing so, help the community and perhaps satisfy their own curiosity about the process without the expense of actually buying the equipment.

Please, I welcome everyone's thoughts on this. If you think it's a ridiculous idea or you think I don't have the technical know-how to be your remote pair of eyes and hands please let me know. I want to learn the theory and process.

Thank you, everyone, for all of your advice and comments.

If you invest in a SW digital radio or a freqmeter, you can calibrate these old horses, and makes the investment cheaper, although with more time spending (alas, is a hobby, after all, but these busy times can call otherwise I know...)

If you invest in a SW digital radio or a freqmeter, you can calibrate these old horses, and makes the investment cheaper, although with more time spending (alas, is a hobby, after all, but these busy times can call otherwise I know...)

Thank you so much for your thoughts. I'd really like to do this with reliable, accurate modern equipment.

It is the tracking generator. I think you mean marker generator. Yes, you can loosely couple a second generator to create a marker blip

Great to see you had the Tiny SA. You were highlighting my fear as it only would examine RF spectrum. It is not what I would call a network analyser since it does not have a sweep source that tracks with the spectrum analyser display.

The WinWT4 Spectrum Analyzer RF Signal Generator With Tracking Generator appears to be more appropriate and is cheaper too! It has a tracking generator output which is fed to the device under test, in this case the input to the IF amplifier. The output is applied to the RF input of the Spectrum analyser. Then you use the the software to provide the display of the sweep on a computer. No need for an oscilloscope.

Here is the link again:

https://www.ebay.com/itm/126284122318

Great to see you had the Tiny SA. You were highlighting my fear as it only would examine RF spectrum. It is not what I would call a network analyser since it does not have a sweep source that tracks with the spectrum analyser display.

The WinWT4 Spectrum Analyzer RF Signal Generator With Tracking Generator appears to be more appropriate and is cheaper too! It has a tracking generator output which is fed to the device under test, in this case the input to the IF amplifier. The output is applied to the RF input of the Spectrum analyser. Then you use the the software to provide the display of the sweep on a computer. No need for an oscilloscope.

Here is the link again:

https://www.ebay.com/itm/126284122318

Yes I looked at these in some detail last night. It's worth a shot, even just as a product review for everyone to comment on. The cheapest option isn't necessarily a requirement as I'd gladly spend up to $400 or so for a good quality instrument. I believe these are manufactured and shipped from China so I imagine QA might be an issue and shipping may take several weeks to get to me. I'll order one and we can use it when it arrives but I'm still open to other suggestions even if they are more expensive options.

I want to find the optimal method and equipment to do alignments on TVs from this era. I'm a bit tired of purchasing vintage equipment in an effort to do this. It seems to always be compromised by inaccuracy and reliability issues.


I think the best approach is a secondhand HP Network analyser. I see a bunch on ebay from modest priced to the astronomical. The HP test equipment in its day was top notch. My HP8600a/HP8601a is essentially a network analyser requiring a separate oscilloscope. It is good for frquencies from 100kHz to 108MHz and use it to sweep align radio and TV sets. I last used it to aligh an RCA CT100 color set and and RCA AR88D Communications Receiver.

The HP8601a Sweeper Generator seems still easy to come by and remains fairly cheap. Mine which I bought on eBay for $40 had a power supply fault which was easily fixed when I received the unit. It however need the HP8600a to provide the true network analysis function as the two devices work in conjenction with each other.

The markr function in the HP8600a/8601a combo works by halting the sweep momentarily to create a blip marking the frequency. There are five independently adjustable marker blips which makes it ideal to simultaneously mark the three traps plus a coulpe to define the passband. Selecting a specific marker makesit brighter on the sweep display and you have a vernier adjustment with accurate digital readout so that the marker is precise to within a few Hertz at 21.25MHz.

New this eqipment in the 1970's was about $8,000 for the pair and I bought them at the time about twenty years ago for about $80 because they provided the best and cheapest solution for my vintage radio TV needs. I higly recommend them for this sort5 of work.

https://xdevs.com/doc/HP_Agilent_Keysight/HP%208600A%20Operating.pdf

https://xdevs.com/doc/HP_Agilent_Keysight/HP8601A.pdf

Here are the HP8600a and HP8601a on ebay. The HP8600a is an earlier version with nixie tubes but otherwise the same. Mine is a bit later using an LED display

https://www.ebay.com/itm/355831629661?itmmeta=01J53G83CS8RCX9MRXFDNCGSCP&hash=item52d937c75d:g:iKgAAOSw~XJmgXAy&itmprp=enc%3AAQAJAAAA8OYmzQRTg38IDlptlA67PrfKzR5V1 vQLAQNhaHEtCdPHSl4Be2RTareCU3Bxt%2FSNIRiI8BHC%2F9S I81K%2FsMZDrj7JhcxKtXa%2Fk2nlJ8PVMM8%2F3MdjQ4FH6d5 6uKNP2obTIMtF5WCTw3K1%2BzosWFtOfJN9ufyQbnSXBLz2g31 SvCPJR5LB6ua7cDgozFImFCaQ45XIkB%2F51VJH0f6j3wD9A1Q CWVW1T02MYq7wXDTScsAFAdpiy0ZdpWc9eP0ZRb6%2BxNgSD0n MAfUtRMcXzHCKme44eBn79CObdFq01JAiQqH84eWojuSz4wK0E fpxj0oYkg%3D%3D%7Ctkp%3ABk9SR9C2oPCoZA

https://www.ebay.com/itm/226259002661?epid=1721885693&itmmeta=01J53GF0ADMYYNJZN04YFD7E4K&hash=item34ae166525:g:JtoAAOSwrL1moVIA&itmprp=enc%3AAQAJAAAA4M3bzqO1yiOG9UJ%2F5pdxIJ3wkzx WU%2FEV9eJABXsx4tB6%2FdJkVZszlPWby7MalJQQiVadusTNR GFJi1NpaaTPJHqbx8i432QrmhFnD05ZvRbbA9hVuFHouJ878cr u4weUB3R9TL3V22WQ%2FzptuFl0RLcAgXBMrgkQ7aPo7VnkHCN KLiFqXgEOyqIMyHPCUnUZj1v%2FIZ3KPE%2ByRMTKBxya%2BWN GaNlk1elmoLGxja8KbK41tVEYxfo5DgQz3baENK05qENR1qyYE ei1fTQ0vY5cMOuVWE0PZxMe1AtQ17DvHt8e%7Ctkp%3ABk9SR6 6FvPCoZA

Great to see you had the Tiny SA. You were highlighting my fear as it only would examine RF spectrum. It is not what I would call a network analyser since it does not have a sweep source that tracks with the spectrum analyser display.

https://www.ebay.com/itm/126284122318

I think you misunderstood. The TinySA is a sweep source. You set the start & stop frequency and sweep rate and it outputs swept RF. Newer versions also output a trigger pulse to sync your scope.

What it does not have is markers. For that you can use a second RF generator and loosely couple it at the injection point.

I think it is a great option for an accurate, easy to use sweep alignment tool.

My main issue is the small size. If I were using it regularly, I'd opt for the much bigger and more capable tinySA Ultra. I believe it can output two frequencies so it might be possible to sweep one output and use the other for a marker.

https://www.amazon.com/AURSINC-TinySA-Spectrum-Analyzer-Built/dp/B0BMPSSFTK

(edit)
Took a quick look at the specs. https://tinysa.org/wiki/pmwiki.php?n=TinySA4.TechnicalDescription
The second output is for calibration and only does 30, 15, 10, 4, 3, 2 or 1 MHZ

So perhaps use a TinySA Ultra for sweeping and TinySA basic for the marker (or any other RF generator for that matter).

I think the best approach is a secondhand HP Network analyser. I see a bunch on ebay from modest priced to the astronomical. The HP test equipment in its day was top notch. My HP8600a/HP8601a is essentially a network analyser requiring a separate oscilloscope. It is good for frquencies from 100kHz to 108MHz and use it to sweep align radio and TV sets. I last used it to aligh an RCA CT100 color set and and RCA AR88D Communications Receiver.

The HP8601a Sweeper Generator seems still easy to come by and remains fairly cheap. Mine which I bought on eBay for $40 had a power supply fault which was easily fixed when I received the unit. It however need the HP8600a to provide the true network analysis function as the two devices work in conjenction with each other.

The markr function in the HP8600a/8601a combo works by halting the sweep momentarily to create a blip marking the frequency. There are five independently adjustable marker blips which makes it ideal to simultaneously mark the three traps plus a coulpe to define the passband. Selecting a specific marker makesit brighter on the sweep display and you have a vernier adjustment with accurate digital readout so that the marker is precise to within a few Hertz at 21.25MHz.

New this eqipment in the 1970's was about $8,000 for the pair and I bought them at the time about twenty years ago for about $80 because they provided the best and cheapest solution for my vintage radio TV needs. I higly recommend them for this sort5 of work.

https://xdevs.com/doc/HP_Agilent_Keysight/HP%208600A%20Operating.pdf

https://xdevs.com/doc/HP_Agilent_Keysight/HP8601A.pdf

Here are the HP8600a and HP8601a on ebay. The HP8600a is an earlier version with nixie tubes but otherwise the same. Mine is a bit later using an LED display

https://www.ebay.com/itm/355831629661?itmmeta=01J53G83CS8RCX9MRXFDNCGSCP&hash=item52d937c75d:g:iKgAAOSw~XJmgXAy&itmprp=enc%3AAQAJAAAA8OYmzQRTg38IDlptlA67PrfKzR5V1 vQLAQNhaHEtCdPHSl4Be2RTareCU3Bxt%2FSNIRiI8BHC%2F9S I81K%2FsMZDrj7JhcxKtXa%2Fk2nlJ8PVMM8%2F3MdjQ4FH6d5 6uKNP2obTIMtF5WCTw3K1%2BzosWFtOfJN9ufyQbnSXBLz2g31 SvCPJR5LB6ua7cDgozFImFCaQ45XIkB%2F51VJH0f6j3wD9A1Q CWVW1T02MYq7wXDTScsAFAdpiy0ZdpWc9eP0ZRb6%2BxNgSD0n MAfUtRMcXzHCKme44eBn79CObdFq01JAiQqH84eWojuSz4wK0E fpxj0oYkg%3D%3D%7Ctkp%3ABk9SR9C2oPCoZA

https://www.ebay.com/itm/226259002661?epid=1721885693&itmmeta=01J53GF0ADMYYNJZN04YFD7E4K&hash=item34ae166525:g:JtoAAOSwrL1moVIA&itmprp=enc%3AAQAJAAAA4M3bzqO1yiOG9UJ%2F5pdxIJ3wkzx WU%2FEV9eJABXsx4tB6%2FdJkVZszlPWby7MalJQQiVadusTNR GFJi1NpaaTPJHqbx8i432QrmhFnD05ZvRbbA9hVuFHouJ878cr u4weUB3R9TL3V22WQ%2FzptuFl0RLcAgXBMrgkQ7aPo7VnkHCN KLiFqXgEOyqIMyHPCUnUZj1v%2FIZ3KPE%2ByRMTKBxya%2BWN GaNlk1elmoLGxja8KbK41tVEYxfo5DgQz3baENK05qENR1qyYE ei1fTQ0vY5cMOuVWE0PZxMe1AtQ17DvHt8e%7Ctkp%3ABk9SR6 6FvPCoZA

Got both the eBay items, the HP8600a and HP8601a pair.

Got both the eBay items, the HP8600a and HP8601a pair.

Wow that was fast. I have a lot of experience with these things and will be happy to help you set it up.

There is a fair bit of literature on the web about these devices. I would suggest when you obtain then to set up a test network and confirm operation. Generally there is rarely much wrong with this era HP stuff but it is best to make sure.

Wow that was fast. I have a lot of experience with these things and will be happy to help you set it up.

There is a fair bit of literature on the web about these devices. I would suggest when you obtain then to set up a test network and confirm operation. Generally there is rarely much wrong with this era HP stuff but it is best to make sure.

Looking forward to it!

I’m going to start researching these instruments and reading the manuals in preparation for delivery. If this works well, I’ll be able to begin to learn about this process and I’ll be able to clear off some shelves! The Tiny SA I originally ordered came today as well so I’ll be playing with that in the meantime. Should be about a week before these arrive so I’ll probably start a new thread then or continue to post in this one. I’ll keep you updated as to arrival time as I get closer to knowing when they’ll be delivered.

The TinySA will be useful to check if the HP gear is working properly.

It’s a cool little piece. I imagine at the least I can use it as an accurate RF source?

I think you misunderstood. The TinySA is a sweep source. You set the start & stop frequency and sweep rate and it outputs swept RF. Newer versions also output a trigger pulse to sync your scope.

What it does not have is markers. For that you can use a second RF generator and loosely couple it at the injection point.

I think it is a great option for an accurate, easy to use sweep alignment tool.

My main issue is the small size. If I were using it regularly, I'd opt for the much bigger and more capable tinySA Ultra. I believe it can output two frequencies so it might be possible to sweep one output and use the other for a marker.

https://www.amazon.com/AURSINC-TinySA-Spectrum-Analyzer-Built/dp/B0BMPSSFTK

(edit)
Took a quick look at the specs. https://tinysa.org/wiki/pmwiki.php?n=TinySA4.TechnicalDescription
The second output is for calibration and only does 30, 15, 10, 4, 3, 2 or 1 MHZ

So perhaps use a TinySA Ultra for sweeping and TinySA basic for the marker (or any other RF generator for that matter).

I understood. A Network Analyser has a calibrated scale display incorporated so that you do not need markers. The precision of the scale is the limiting factor here and I do not think a separate marker source is the answer. More expensive Network analysers have the precision. The cheaper device I suggested the software client may provide sufficient precision to negate the need for a separate marker.

The HP8600a/HP8601a combo sits in between a more modern and expensive Network Analyser and the older sweep gen/ marker solution but is much more efficient. It's versatility is you can use it as an accurate signal source which can be AM and FM modulated. And than be quickly switched to sweep mode with up to five markers with the flip of a few switches.

I shall purchase a Tiny SA as I would like to explore it.

I think you misunderstood. The TinySA is a sweep source. You set the start & stop frequency and sweep rate and it outputs swept RF. Newer versions also output a trigger pulse to sync your scope.

What it does not have is markers. For that you can use a second RF generator and loosely couple it at the injection point.

I think it is a great option for an accurate, easy to use sweep alignment tool.

My main issue is the small size. If I were using it regularly, I'd opt for the much bigger and more capable tinySA Ultra. I believe it can output two frequencies so it might be possible to sweep one output and use the other for a marker.

https://www.amazon.com/AURSINC-TinySA-Spectrum-Analyzer-Built/dp/B0BMPSSFTK

(edit)
Took a quick look at the specs. https://tinysa.org/wiki/pmwiki.php?n=TinySA4.TechnicalDescription
The second output is for calibration and only does 30, 15, 10, 4, 3, 2 or 1 MHZ

So perhaps use a TinySA Ultra for sweeping and TinySA basic for the marker (or any other RF generator for that matter).

I understood. A Network Analyser has a calibrated scale display incorporated so that you do not need markers. The precision of the scale is the limiting factor here and I do not think a separate marker source is the answer. More expensive Network analysers have the precision. The cheaper device I suggested the software client may provide sufficient precision to negate the need for a separate marker.

The HP8600a/HP8601a combo sits in between a more modern and expensive Network Analyser and the older sweep gen/ marker solution but is much more efficient. It's versatility is you can use it as an accurate signal source which can be AM and FM modulated. And than be quickly switched to sweep mode with up to five markers with the flip of a few switches.

I shall purchase a Tiny SA as I would like to explore it.

The TinySA will be useful to check if the HP gear is working properly.

That 741 looks amazing. You have been one busy man the past few months!

I understood. A Network Analyser has a calibrated scale display incorporated so that you do not need markers. The precision of the scale is the limiting factor here and I do not think a separate marker source is the answer. More expensive Network analysers have the precision. The cheaper device I suggested the software client may provide sufficient precision to negate the need for a separate marker.

The HP8600a/HP8601a combo sits in between a more modern and expensive Network Analyser and the older sweep gen/ marker solution but is much more efficient. It's versatility is you can use it as an accurate signal source which can be AM and FM modulated. And than be quickly switched to sweep mode with up to five markers with the flip of a few switches.

I shall purchase a Tiny SA as I would like to explore it.

You can do the same with the TinySA. The sweep is very linear. If you set the start/stop freq say for 10-20MHz and you scope has 10 divisions, it will be 1MHz per division.

Personally, I use the newer HP 8662A which does everything you describe in one device.

You can do the same with the TinySA. The sweep is very linear. If you set the start/stop freq say for 10-20MHz and you scope has 10 divisions, it will be 1MHz per division.

Personally, I use the newer HP 8662A which does everything you describe in one device.

I examined the HP8662A Agilent data sheet. I see that it is a wide range signal generator but I could not see it used as a sweeper and marker function combined as in the HP8600a/HP8601a or more expensive network analyser. Can you show me how the HP8662a may perform as I described with the HP8600a/HP8601a combo?

I personally would prefer a newer network analyser with tracking generator, but the cost would overwhelm me on my limited budget.

I examined the HP8662A Agilent data sheet. I see that it is a wide range signal generator but I could not see it used as a sweeper and marker function combined as in the HP8600a/HP8601a or more expensive network analyser. Can you show me how the HP8662a may perform as I described with the HP8600a/HP8601a combo?

I personally would prefer a newer network analyser with tracking generator, but the cost would overwhelm me on my limited budget.

Some of the budget, Chinese analyzers with generator were over $1000! Even with my tendency to throw good cash after bad that’s way outside my hobby piggy bank! The HP combo I ordered should both arrive by next Monday and maybe by the weekend if all goes smoothly.

I examined the HP8662A Agilent data sheet. I see that it is a wide range signal generator but I could not see it used as a sweeper and marker function combined as in the HP8600a/HP8601a or more expensive network analyser. Can you show me how the HP8662a may perform as I described with the HP8600a/HP8601a combo?

I personally would prefer a newer network analyser with tracking generator, but the cost would overwhelm me on my limited budget.

Strange that they don't detail it's sweep capabilities in the spec sheet.

The left side of the control panel is for sweep setting.

https://live.staticflickr.com/65535/53923058165_68ae39b968_z.jpg (https://flic.kr/p/2q9ZLxp)

I also have a newer 8664A which has similar sweep capabilities but even more features.

Both are briliant pieces of engineering and outstanding performance.

Here are the sweep specs from the manual
https://live.staticflickr.com/65535/53923056415_c9bd7625f3_c.jpg (https://flic.kr/p/2q9ZL2e)

Another devotee of the 8662A here. If you can get your hands on one at a reasonable price, you likely will never need another general purpose signal generator. When I got mine, I was able to sell off 4-5 other RF and sweep/marker generators I had accumulated over the years to pay for the purchase!

The only feature that I wish it had was wider bandwidth on the external AM modulation input, so I could feed video into it for signal injection troubleshooting, but the TV service market was DEFINITELY not what these units were designed and priced for originally...

Another devotee of the 8662A here. If you can get your hands on one at a reasonable price, you likely will never need another general purpose signal generator. When I got mine, I was able to sell off 4-5 other RF and sweep/marker generators I had accumulated over the years to pay for the purchase!

The only feature that I wish it had was wider bandwidth on the external AM modulation input, so I could feed video into it for signal injection troubleshooting, but the TV service market was DEFINITELY not what these units were designed and priced for originally...

No...seems like they were designed for space travel and satellite communications! :banana::banana::banana::banana::banana:

Also insanely complicated and challenging to keep in spec. I think you'll be fine with the 8600/8601 combo.

Everything will be here by Monday. Very exciting.

So, then you can put everything you have together on 2 or 3 shelves, and with all the displays and screens, switches, lights,and knobs blinking and flashing and showing stuff, put a fancy joystick in the center, add a large LCD screen, and it will look like a cockpit! :D

Wharp factor one. Arm photon torpedoes. Fire!!!

Hey friends, the digital marker came today. Not much I can do to test its full capabilities except to use it as a frequency counter which it's rated to do up to 15MHz. It can actually go a bit further than that and it's bang on accurate.

https://imagizer.imageshack.com/v2/1024x768q70/923/1UBlr1.jpg

https://imagizer.imageshack.com/v2/1024x768q70/923/BeBbqr.jpg


https://imagizer.imageshack.com/v2/1024x768q70/923/QZdR2H.jpg

That's impressive! Love the nixies :)

They are cute and much brighter than in the photo. I opened it up and it looks mostly original. There’s a board mounted can capacitor and a couple of Sprague electrolytics. Not dusty inside at all. I pulled a couple of the boards just to lightly clean the contacts and buttoned it back up. It works great so I’ll leave well enough alone.

Excellent. When is the generator due to arrive?

And the markers are highlighted for identification by pressing the center buttons on the marker adjustment controls. Are they intact and latch? The only issue I had with mine was one of the buttons was broken and missing.

Buttons are good. The partner piece is due Monday!

...and is out for delivery!

Excellent. When is the generator due to arrive?

And the markers are highlighted for identification by pressing the center buttons on the marker adjustment controls. Are they intact and latch? The only issue I had with mine was one of the buttons was broken and missing.

You have me a bit concerned with the "latch" reference. Is the button in the center of each marker adjustment knob supposed to lock in some sort of on/off detent? None of the five do. There's very little travel on the center buttons and no discernable click or an indication something is being turned on and off.

OK the 8601 is here It powers up. I think I might need a few more BNC cables! I tried to configure the instruments for the sweep characteristics test and after 5 hook-ups, I ran out!

You have me a bit concerned with the "latch" reference. Is the button in the center of each marker adjustment knob supposed to lock in some sort of on/off detent? None of the five do. There's very little travel on the center buttons and no discernable click or an indication something is being turned on and off.

The five marker controls on the HP8600a have center selector buttons. When you press the button it latches. Pressing any other the others release it and selects the other. It is a one out of five latch and is purely mechanical.

OK the 8601 is here It powers up. I think I might need a few more BNC cables! I tried to configure the instruments for the sweep characteristics test and after 4 hook-ups, I ran out!

I count four interconnection hookup cables

Blanking
Sweep
Sweep Inhibit
Aux out of the Sweeper tthe counter in rear.

In addition you need the generator RF out to apply to the circuit under test and a cable, typically scope probe to it's vertical input.

Have you verified that the HP8601a produces a CW output which frequency can be measured on the HP8600a?

Refer to the Operator check on pages 21 and 22 of the BAMA HP8601a manual pdf.

The five marker controls on the HP8600a have center sector buttons. when you press the button it latches. Pressing any other the others release it and selects the other. It is a one out of five latch and is purely mechanical.

Doesn’t do that. I’ll have to get inside of it. If it’s a mechanical system I should be able to fix it.

I count four interconnection hookup cables

Blanking
Sweep
Sweep Inhibit
Aux out of the Sweeper tthe counter in rear.

In addition you need the geberator RF out to apply to the circuit under test and a cable, typically scope probe to it's vertical input.

Have you verified that the HP8601a produces a CW output which frequency can be measured on the HP8600a?

Refer to the Operator check on pages 21 and 22 of the BAMA HP8601a manual pdf.

Probably Wednesday night before I can work on the repair to the 8600 and do the testing on the 8601. Work tomorrow and family responsibilities but I’ll be asking for questions in the interim! Thanks so much for your help and time. Means a lot.

I count four interconnection hookup cables

Blanking
Sweep
Sweep Inhibit
Aux out of the Sweeper tthe counter in rear.

In addition you need the geberator RF out to apply to the circuit under test and a cable, typically scope probe to it's vertical input.

Have you verified that the HP8601a produces a CW output which frequency can be measured on the HP8600a?

Refer to the Operator check on pages 21 and 22 of the BAMA HP8601a manual pdf.

So I have a few questions about this. Some of them will sound like I have no idea what I am doing and in several cases, that's absolutely true! I would like to start with the operator checks on the pages you specified.

Regarding the test setup below...

https://imagizer.imageshack.com/v2/800x600q70/924/3QHbgP.jpg

The connections shown are the only connections needed for this part of the evaluation? Blanking and sweep etc between the 8600 and the 8601 on the rear of both instruments do not need to be connected correct?

What does CW mean? Center wavelength?

RF Detector? What do I use for this? In an analysis setup, it would be the device under test but shouldn't there be a standard for it in a check setup?

For the scope inputs, the sweep output goes to the horizontal (X) input and the output of the RF Detector (whatever that is!) goes to the "Y" input? My scope needs to be in X-Y mode correct?

There...I've put my ignorance out there for all to see! Sometimes, the terms you guys throw around go right over my head! More idiotic questions to come!

CW means continuous (unmodulated) wave it's an ancient ham radio term that predates radio being able to convey audio.

Some alignment procedures require a detector probe, some get away with connecting to the detector in the TV or radio.

Thanks Tom

Buttons fixed on the 8600. Stuck tab on the switch rail. Lubricates and working fine now.

So I have a few questions about this. Some of them will sound like I have no idea what I am doing and in several cases, that's absolutely true! I would like to start with the operator checks on the pages you specified.

Regarding the test setup below...

https://imagizer.imageshack.com/v2/800x600q70/924/3QHbgP.jpg

The connections shown are the only connections needed for this part of the evaluation? Blanking and sweep etc between the 8600 and the 8601 on the rear of both instruments do not need to be connected correct?

What does CW mean? Center wavelength?

RF Detector? What do I use for this? In an analysis setup, it would be the device under test but shouldn't there be a standard for it in a check setup?

For the scope inputs, the sweep output goes to the horizontal (X) input and the output of the RF Detector (whatever that is!) goes to the "Y" input? My scope needs to be in X-Y mode correct?

There...I've put my ignorance out there for all to see! Sometimes, the terms you guys throw around go right over my head! More idiotic questions to come!

Yes that is correct on both counts. we want to verify the thing is working.

The blanking and sweep inhibit are to display the markers on the scope. Instead of creating a beat blip marker where you combine the marker generator with the sweep signal at the input or output, this system introduces a marker by momentarily halting the sweep at the frequency point to make it appear brighter.

For the RF detector, I used a simple diode capacitor resistor network like the one attached. The diode i used was the ubiquitous 1N4148. It essentially rectifies and filters to remove the RF carrier and rf envelope to register on the scope. Try bypassing it and providing the y input of the scope has sufficient bandwidth (eg a 100MHz scope) bypassing it you will see the rf carrier sweep.

I have attached the use of this equipment to obtain my IF response with markers which went through the RF detector of the television set as yours will and a sweep of the luma reponse of the set minus an RF detector. This will demonstrate the presence and absence of the RF detector.

Buttons fixed on the 8600. Stuck tab on the switch rail. Lubricates and working fine now.

Excellent! One of the results of getting old.

Yes that is correct on both counts. we want to verify the thing is working.

The blanking and sweep inhibit are to display the markers on the scope. Instead of creating a beat blip marker where you combine the marker generator with the sweep signal at the input or output, this system introduces a marker by momentarily halting the sweep at the frequency point to make it appear brighter.

For the RF detector, I used a simple diode capacitor resistor network like the one attached. The diode i used was the ubiquitous 1N4148. It essentially rectifies and filters to remove the RF carrier and rf envelope to register on the scope. Try bypassing it and providing the y input of the scope has sufficient bandwidth (eg a 100MHz scope) bypassing it you will see the rf carrier sweep.

I'll make the detector. Thank you for the design! There may be issues with the 8601. I don't think I'm getting RF output. Output level doesn't change. I'll need to break into it and see what's going on!

Different frequency range in this TV but oh that CT100 IF response curve is so beautiful!!!!! If I ever see something like that on my scope I'll send you first class, round trip tickets to Maui!!!!!!

I'll make the detector. Thank you for the design! There may be issues with the 8601. I don't think I'm getting RF output. Output level doesn't change. I'll need to break into it and see what's going on!

Without the HP8600a, the HP8601a should act as a standard signal generator. If you have a 100MHz scope, simply connect the probe to the RF output and set it to say 10MHz. Switch it to CW mode and you can ignore the sweep mode switches for a moment. Just crank up the output and set the TIME/DIV on the scope to 0.1uS per division and see if you can see a high frequency sinusoid on the scope.

Here is the setting of my HP8601a generating a 10MHz CW carrier and the scope set to 0.1us per division and scope set to 0.1volts/div with a 10x probe = 1.0 volts per division.

Yeah I’m not getting the continuous sine wave out of the RF section of the 8601. Something is whacked with the RF generator. I’m going to have to break into this thing and see what’s going on. Thank you for taking the time to setting up the generator and scope and documenting the results for me. The TinySA has a frequency generator in it that gives me a clean CW trace using the same scope. I have an HP and a budget basic Chinese scope and I don’t get the continuous wave. They are both 100MHz scopes

I’ll be back on it tomorrow night. I’m pretty sure I can fix a balky RF generator section. Thanks for hangin’ in with me.

Ah! in the test circuit I forgot the most important element: the diode!

Here is the revised drawing.

I think this is just noise. Output level looks dead. There's a guy on eBay selling these restored/calibrated and certified accurate. Maybe I'll look into those units if I can't get this one working. My ongoing luck with this endeavor and obtaining TVs from this era that require a recap and a few tweaks to get a good picture continues. Kinda ridiculous at this point. I feel cursed!

https://imagizer.imageshack.com/v2/800x600q70/924/EHClwe.jpg

https://imagizer.imageshack.com/v2/800x600q70/924/4nWAIE.jpg

https://imagizer.imageshack.com/v2/800x600q70/924/IhZQMS.jpg

Hmm. It may be the output hybrid amplifer. I earlier did research on this and there is a guy who reproduced a better than original amplifier replacement. I was lucky with mine.

He used to manufacture and sell the amplifiers but no more. However he has kindly provided the component list, schematic and PCB layout to build one. That is a project within itself.

Here are the links.

http://www.dasarodesigns.com/product/reproduction-hp-8601a-output-hybrid-5086-7112-5086-3012-1820-0150/

http://www.dasarodesigns.com/projects/reproducing-the-hp-8601a-output-hybrids-5086-7112-5086-3012-1820-0150/

I think I'm just going to buy one that I know is working and keep the one on the bench right now for parts. I'll probably have a go at trying to make it work but at least I'll have an instrument I know I can trust. Are you sure you want to keep your cart hitched to my wayward star!? I seem to be jinxed! It'll be another week before the next one is delivered.

Here is a second one exactly the same as the one I just bought from the same seller. Apparently he likes these as much as you do!!!

https://www.ebay.com/itm/226164949008?_trkparms=amclksrc%3DITM%26aid%3D7770 08%26algo%3DPERSONAL.TOPIC%26ao%3D1%26asc%3D202401 31095853%26meid%3D082078ebce614eb29f5de057fcb37534 %26pid%3D101949%26rk%3D1%26rkt%3D1%26itm%3D2261649 49008%26pmt%3D0%26noa%3D1%26pg%3D4375194%26algv%3D RecentlyViewedItemsV2WithMLRV6RankerPricelessTop30 Features%26brand%3DHP&_trksid=p4375194.c101949.m162918&_trkparms=parentrq%3A75ef478e1910a8dc1579fae6ffffa ede%7Cpageci%3Ae66ed243-5fe0-11ef-8a70-5e1ed0606ac1%7Ciid%3A1%7Cvlpname%3Avlp_homepage

Oof, this is getting really expensive.

Oof, this is getting really expensive.

Always seems to!

Oof, this is getting really expensive.

my thoughts exactly, I would never be able to put out the kind of $$$ for equipment like this!
If i ever do try to align my FADA, I would just do the MIN/MAX steps laid out in the SAMS with the RF generator and hope it helps it like it did with my Arvin.

my thoughts exactly, I would never be able to put out the kind of $$$ for equipment like this!
If i ever do try to align my FADA, I would just do the MIN/MAX steps laid out in the SAMS with the RF generator and hope it helps it like it did with my Arvin.

Married for a long time to an understanding, physician wife. Me?...I'm a bum!

Well...about the only thing I would be capable of fixing might be the issue...the 1/8A 0.75V slow blow fuse on the power board is open. I have a replacement floating around somewhere....


https://imagizer.imageshack.com/v2/1024x768q70/923/yAD95v.jpg

Nope...not entirely. Have a very low power clean 12.5MHz sine wave. The frequency doesn't change whatever I do to the wheel and the output level has no effect on the amplitude. The meter still doesn't move into the readable zone. Going to clean some controls and see what that does.

No change with cleaning. When I found the blown fuse, I almost raced to the laptop to cancel my order for the $400+ sweep generator but I didn't and thank goodness. I'll see if the seller wants to buy this one to refurbish. We'll see. I guess we're back on hold again.

As I say it is the luck of the draw. As I said mine was something like $35 and I plugged it in and it worked. Even the one you bought I suspect there is not much wrong with it. Could go through it with you on another thread 😉.

Fortunately the 8601a is pretty common.

Before you give up on this 8601a, could you run through a few checks? A blown fuse suggests perhaps a power supply failure.

The 1/8A fuse looks like it was for theb-75 volt supply. You should check to ensure it is -75v and while you are at it the +20v supply.

The good thing is that after you changed the fuse, you got a 12.5Mhz sine wave. The suggests the hybrid output amplifier is good and the internal fault may be minor.

Here is the link to the BAMA stiched schematics. The Power Supply is fig_8_26

https://bama.edebris.com/manuals/hp/8601a/

Thank you so much. I’ll look into the voltage.

Before you give up on this 8601a, could you run through a few checks? A blown fuse suggests perhaps a power supply failure.

The 1/8A fuse looks like it was for theb-75 volt supply. You should check to ensure it is -75v and while you are at it the +20v supply.

The good thing is that after you changed the fuse, you got a 12.5Mhz sine wave. The suggests the hybrid output amplifier is good and the internal fault may be minor.

Here is the link to the BAMA stiched schematics. The Power Supply is fig_8_26

https://bama.edebris.com/manuals/hp/8601a/


The -70 and +20 volt voltages are fine. It's the -6.3 volt line that's suspect. Reading only -3.7V

Maybe the diode to ground is bad? CR2?...at least It looks like a diode to me but where to find it on this board???


https://imagizer.imageshack.com/v2/1024x768q70/922/S1XxE4.jpg

Or maybe the 47uf electrolytic?

With it powered on, are you able to find the correct voltages?

From your picture below and from the board layout in the manual, the edge connections at the bottom of your photograph run from 1 on the left to 15 on the right. measuer with respect to ground (chassis):

7-9 is +20v
10-12 is -6.3v
The the line pointing to the aluminum can of C12 is -75v

Yes that’s exactly where I read the DC voltages. The +20 and -75 voltages were perfect but the -6.3 voltage was only -3.7 V DC

Then as that is a reference voltage, something is amiss there. I will think about this.

It’s that voltage right on the -6.3V fuse. I don’t know if that’s before the board or after.

Here is a bigger view of the removed board. You can't see it too well but the resistor between the heat sinks has a chip on the outside coating that is more than just a surface mar. It reads 136 ohms. All of the electrolytic caps I can measure are about 20% high.

https://imagizer.imageshack.com/v2/1280x1024q70/922/UXdFxX.jpg

Looks like it's a 130 ohm (R4?) resistor so that's fine and 20% high is fine too.
Odd half wave power supply design with the center tap being the -6.3 volt rail.

Could be as simple as CR2 being bad. Looks like it's there for protection. Perhaps it is same to disconnect the load form this board and measure the voltages? That way you could isolate the problem to this board or what it is powering.

So if the Power Supply components are good (as I suspect they are) then one of the circuits is loading the -6.3v down.

I researched where the -6.3v and it goes to the boards listed below. The first thing I would do is to lift the -6.3v one at a time to each board until the until the voltage pops back to -6.3v:
A6 Video Amplifier Assy
A5 VTO
A4 Crystal Oscillator/Mixer
A3 Loop Amplifier/Crysatl Calibrator
A2 Divider/Divider Bypass

When you identify the board, I believe there is a good chance that is where the overall problem is.

Looks like it's a 130 ohm (R4?) resistor so that's fine and 20% high is fine too.
Odd half wave power supply design with the center tap being the -6.3 volt rail.

Could be as simple as CR2 being bad. Looks like it's there for protection. Perhaps it is same to disconnect the load form this board and measure the voltages? That way you could isolate the problem to this board or what it is powering.

CR2 is a voltage reference regulator. It is there to provide a -6.3v reference.

Thank you for all of that work! I’ll see if I can track it down by your process of elimination. How should I go about isolating and disconnecting a specific -6.3V supply trace for a given board? I imagine I identify the numbers of the board tabs that supply a particular circuit board with that voltage and see what happens to the -6.3V reference voltage by isolating and disconnecting a single feeding point but how do I “lift” the single lead for that individual trace?

Banderson's remark CR2 is for protection got me thinking about the circuit again. The design for for the balanced amplifiers required the negative supply. Because the +20v and -6.3v supplies are derived from the same source without a ground reference within the supply itself, the circuit externally determines it.

I have attached a drawing to outline my reasoning. The power supply is actually stacked 20 plus 6.3. The voltages with respect to ground is determined by the ratio of the +20v load and -6.3v load. Because the same amplifiers are across the +20volts and -6.3 volts, the ratio should remain consistently the same. Therefore the 7.2v zener is for protection. If the =20 rail develops a short, it would push the -6.3v very negative unnecessarily damaging components. The 7.2 volt zener therefore prevent the lower rail dipping below -7.2 volts. It also explains wht the zener appears to be a chassis mount hight powered zener external to the circuit board.

I do not think the zener is faulty. I do however think the negave supply is drawing slightly more current than it should hence the dip to ablout 3 volts.

I am going to reason this through over the next day and if you have any questions on my reasoning, let me know.

I would advise not touching the zener as I think it is okay and removing it may jeopardize other circuitry it was intended to protect.

We're getting a bit outside my abilities and I hope as the hands on person, I'm providing accurate information regarding the problem solving. I understand solid state stuff even less than tube stuff! If we're talking about relatively low DC voltage circuits affecting one another, I guess I should be much more specific about providing exact values. A few years of measuring and evaluating voltages in the hundreds, and seeing 380V on a circuit that is supposed to have 400V on it thinking 380V isn't an issue, I think I better tighten my error bars. In reality, the +20V line is closer to 22V and the -75V is more like -74.5V (again, these aren't exact...I'm at work and I don't have it in front of me!)

Bottom line...I don't want to keep anyone up late at night chewing and contemplating this trying to problem solve it if I'm not providing accurate data and facts. I'll recheck the voltages this evening and provide accurate information out to 2 decimal places.

We're getting a bit outside my abilities and I hope as the hands on person, I'm providing accurate information regarding the problem solving. I understand solid state stuff even less than tube stuff! If we're talking about relatively low DC voltage circuits affecting one another, I guess I should be much more specific about providing exact values. A few years of measuring and evaluating voltages in the hundreds, and seeing 380V on a circuit that is supposed to have 400V on it thinking 380V isn't an issue, I think I better tighten my error bars. In reality, the +20V line is closer to 22V and the -75V is more like -74.5V (again, these aren't exact...I'm at work and I don't have it in front of me!)

Bottom line...I don't want to keep anyone up late at night chewing and contemplating this trying to problem solve it if I'm not providing accurate data and facts. I'll recheck the voltages this evening and provide accurate information out to 2 decimal places.

You should not worry about keeping anyone up late. You have provided accurate facts. It is just that sometime the HP engineers were trying to be too clever (my opinion). When troubleshooting, the power supply often provides clues to what is wrong and right now we are only attempting to understand what is wrong. The understanding of the power supply sheds new light and the fact the +20v is spot on and the -6.3v is a bit low to me is not yet a red warning.

Let's review the symtoms again:

"...Have a very low power clean 12.5MHz sine wave. The frequency doesn't change whatever I do to the wheel and the output level has no effect on the amplitude. The meter still doesn't move into the readable zone..."

To me this again is pointing to the output hybrid amplifier. I think we should step back and reflect how to confirm this.

I agree with your reasoning about the power supply. It is actually very similar to how the power supply works for the RCA TV.

Perhaps Chris can put his scope on the input to the hybrid amp?

I could...if you guys know where I should attach it or at least look for it. However it wouldn't be until later today.

You should not worry about keeping anyone up late. You have provided accurate facts. It is just that sometime the HP engineers were trying to be too clever (my opinion). When troubleshooting, the power supply often provides clues to what is wrong and right now we are only attempting to understand what is wrong. The understanding of the power supply sheds new light and the fact the +20v is spot on and the -6.3v is a bit low to me is not yet a red warning.

Let's review the symtoms again:

"...Have a very low power clean 12.5MHz sine wave. The frequency doesn't change whatever I do to the wheel and the output level has no effect on the amplitude. The meter still doesn't move into the readable zone..."

To me this again is pointing to the output hybrid amplifier. I think we should step back and reflect how to confirm this.

Well...if +22VDC is still considered spot on then we're good!!!!!

You should not worry about keeping anyone up late. You have provided accurate facts. It is just that sometime the HP engineers were trying to be too clever (my opinion). When troubleshooting, the power supply often provides clues to what is wrong and right now we are only attempting to understand what is wrong. The understanding of the power supply sheds new light and the fact the +20v is spot on and the -6.3v is a bit low to me is not yet a red warning.

Let's review the symtoms again:

"...Have a very low power clean 12.5MHz sine wave. The frequency doesn't change whatever I do to the wheel and the output level has no effect on the amplitude. The meter still doesn't move into the readable zone..."

To me this again is pointing to the output hybrid amplifier. I think we should step back and reflect how to confirm this.

Let me be a bit more specific about the symptoms. The output level DOES have an effect on the amplitude in that whenever you select anything other than a +10dBm level, the signal goes away. The 12.5MHz CW is visible on just that one intensity setting.

Which makes sense if the output amp is not working correctly. A little bit of signal is getting out on the highest output level setting, but it's so small on the other ranges you can't see it at all.

Which makes sense if the output amp is not working correctly. A little bit of signal is getting out on the highest output level setting, but it's so small on the other ranges you can't see it at all.

It's not the highest...+20dBm is the highest and there's no signal there. I cleaned the wafer switch as best as contact cleaner and rapid twisting provides.

Ah, my mistake. Could be a problem in the attenuator then. Wafer switch? The attenuator is shown on page 8.21. It's a cam shaft with specialized switch contacts. Please do NOT open it up and spray cleaner in there.
Cleaning controls in higher end test equipment is a bit of an art.

I wonder what I remember cleaning then??? I certainly did not open anything up. Anyway, my mistake. Probably one of the sweep toggle switches I remember cleaning but thank you for that piece of knowledge. Part of my education I first mentioned. Precision instrument not to be cleaned like a Motorola volume pot!

Ah, my mistake. Could be a problem in the attenuator then. Wafer switch? The attenuator is shown on page 8.21. It's a cam shaft with specialized switch contacts. Please do NOT open it up and spray cleaner in there.
Cleaning controls in higher end test equipment is a bit of an art.

The attenuator is that giant bank vault case the knob shaft goes into...yes yes...I remember that. No I didn't mess with it.

Let me see if I get this and maybe this is what Bob and Penthode have been talking about but in a way I don't understand. I'm trying to keep up with the troubleshooting logic behind what you guys are saying.

I read Penthode's post about the supply voltage being stacked to make the 20 and -6.3 voltages available. Both voltages are across the amplifiers and the draw from those amplifiers is what keeps the voltage ratio the same? The fact that I'm getting a sine wave of 12.5MHz means the preamp is probably working OK and that primary amplification is missing? But if the voltage ratio is off in the preamp and it is getting -3.7 volts, the same as the output amplifier, wouldn't it be affected as well?

I'm giving myself a headache!


https://imagizer.imageshack.com/v2/1024x768q70/922/H55vLq.jpg

Load plus regulation should keep the voltages at 20 and -6.3, but we suspect something may be drawing too much current and throwing the voltage off.

-6.3 to -3.7 isn't that big a difference and I would expect the circuits to keep working to some extent.

I don't know if this adds anything to the troubleshooting but the 20V line is reading 23.5V on this input lead and the -6.3 input lead is reading essentially 0.

https://imagizer.imageshack.com/v2/1280x1024q70/922/LBTdMY.jpg

Yeah I believe that container holds the hybrid output amplifier. I looks as if it may be the Achilles heel. Check the link to the guy that reconstructed and made a replacement. There is a lot of useful information there.

Also, if you look at the diagram for the output amp, the -6.3v is only switched in at the +20dBu attenuator setting. I believe to get better linearity at the high level setting.

OK will do...Bob mentioned checking some of the test points on my scope and report what shows up. I'm at the bench with the bottom off.

Sent an email to Dasaro to see if there's any chance he'd make one. We'll see.

YOU'VE GOT TO BE KIDDING ME? A BROKEN SOLDER JOINT?

This can't be it:scratch2::scratch2::scratch2::scratch2:

https://imagizer.imageshack.com/v2/1280x1024q70/924/uX5iMv.jpg

Nope...didn't change a thing. I think I'm going to button this up and wait for the one that's on schedule to arrive Monday. A blown fuse and a broken solder lead in the suspected problem zone...both repaired and nothing. That's about as much as my electronic hopes can stand.

Looks like the new purchase 8001a is arriving today. When it does I’ll go through it and make sure all is well. For the alignment, I’m going to start a new thread. This one has pleasantly meandered all over the place.

Hopefully you will resolve the issue with the faulty generator.
It looks as if the hybrid amp is faulty on this one. To confirm you could try some more tests. Also we would be curious the reply you may receive in response to your request for the new replacement.

He was very prompt and kind in his response but he said what you had suggested earlier that the transistors to build it were no longer available