I have the opportunity to get a hold of a couple of HP Signal Generators

[init4fun]

Originally Posted by vortalexfan

Look, I'm not trying to start trouble here, but when you've been bullied all your life like I have for having a learning disability (high functioning autism) that apparently even to this day not many people seem to be aware of it and its impacts on people's lives, then you would be kind of leary of people's comments as well, whether they were meant out of spite or not.

Another key thing to know when communicating with people with Autism is that people with autism don't handle sarcasm well (we tend to take things too seriously when it comes to that because we don't pick up on sarcasm as easily.)

So when comments like the ones you make, where you give your "opinons" about something and you're talking in a "sarcastic" manner, then it would be best to not do that, and just give a straight up yes or no answer, rather than making a sarcastic remark with vague references to old hollywood movies.

Well, I can say with all certainty that I had no clue you have autism, so there is no way I was bullying you because you have it. Your right about this; sarcasm, even if meant in a more joking and less malicious way, doesn't always come across right in print, especially with people we don't really know beyond their internet personas. I do wish you well with your future electronic endeavors involving the HP signal generators

[vortalexfan]

Originally Posted by init4fun

Well, I can say with all certainty that I had no clue you have autism, so there is no way I was bullying you because you have it. Your right about this; sarcasm, even if meant in a more joking and less malicious way, doesn't always come across right in print, especially with people we don't really know beyond their internet personas. I do wish you well with your future electronic endeavors involving the HP signal generators

Alright thanks, I'm glad we were able to work this out.
I apologize for getting upset at you, part of it was that I misread your initial posting and I thought the message said one thing when it said another.

[Polaraligned]

Originally Posted by vortalexfan

Well I picked up the HP HP 8640B on Wednesday and I got it home and hooked it up to try it out and it doesn't seem to be wanting to put out a test tone (400 hz or 1kHz tone) ar the frequency dialed in on the frequency readout (for example I tried to dial in .45500 MHz on the readout or 455 kHz), and when I tried to tune to the low end of the AM band on a known working AM radio the test tone couldn't be heard and neither could the RF signal unless I went up almost 35 kHz on the readout on the signal generator.

Any ideas as to what's going on here? Is my radios IF Freguency that far off or is there something wrong with the calibration of the signal generator?

What test equipment do you have at your disposal? An oscilloscope and frequency counter would be nice. Maybe modulation is not working? How are you coupling signal into radio? The readout on these is just a frequency counter as they are not synthesized, so the internal cavity oscillator is working, but you still may not be getting output if the attenuator is not working. It is just hard to say from what you are describing without trying to look for signal output on oscilloscope. These are very difficult units to work on as is ALL HP equipment. If you are not experienced with these it may just be better getting a working unit. Did your friend say the unit was working? You NEED the service manual to repair these. HP has flow charts for troubleshooting, but that also requires test equipment to do so.

[vortalexfan]

Originally Posted by Polaraligned

What test equipment do you have at your disposal? An oscilloscope and frequency counter would be nice. Maybe modulation is not working? How are you coupling signal into radio? The readout on these is just a frequency counter as they are not synthesized, so the internal cavity oscillator is working, but you still may not be getting output if the attenuator is not working. It is just hard to say from what you are describing without trying to look for signal output on oscilloscope. These are very difficult units to work on as is ALL HP equipment. If you are not experienced with these it may just be better getting a working unit. Did your friend say the unit was working?

I do have an oscilloscope, would I just hook the output of the signal generator up to one of the inputs on the 'scope and see if it picks up a signal?

As for how I was coupling it up to the radio, I was using some 50 ohm BNC clip leads and clipping them to the proper coupling points on the radio.

[Polaraligned]

Originally Posted by vortalexfan

I do have an oscilloscope, would I just hook the output of the signal generator up to one of the inputs on the 'scope and see if it picks up a signal?

As for how I was coupling it up to the radio, I was using some 50 ohm BNC clip leads and clipping them to the proper coupling points on the radio.

Yes, you should be able to see a clean sine wave on the oscilloscope with modulation turned off. If your o-scope has a 50 ohm input use that, otherwise a high impedance input is ok but the amplitude will be a little off. Sinewave should still be clean.

Clipping the 50 ohm output to the radio is dangerous for the signal generator. You should use a .01uF or so capacitor to isolate the signal generator from the radio.

[vortalexfan]

Originally Posted by Polaraligned

Yes, you should be able to see a clean sine wave on the oscilloscope with modulation turned off. If your o-scope has a 50 ohm input use that, otherwise a high impedance input is ok but the amplitude will be a little off. Sinewave should still be clean.

Clipping the 50 ohm output to the radio is dangerous for the signal generator. You should use a .01uF or so capacitor to isolate the signal generator from the radio.

Ok. I've got a BNC to BNC cable I'll try hooking the signal generator up to the 'scope and see if I get a clean sine wave.

[vortalexfan]

It took me a while to figure out which hookup on the 'Scope to hook the signal generator up to to test the signal generator, but I was able to figure out that the signal generator is indeed working as I was able to get a clean sine wave onto the 'scope.

See picture below.

[jr_tech]

Does the frequency indicated on the signal generator display correspond reasonably well with that measured by the scope?

jr

[vortalexfan]

Originally Posted by jr_tech

Does the frequency indicated on the signal generator display correspond reasonably well with that measured by the scope?

jr

I'm actually working on the signal generator that doesn't have the digital readout right now, and for some reason when I hook my stand alone frequency counter up to it, it doesn't register on my frequency counter, and when I used it to "radiate" a signal to my Zenith Royal 2000-1 radio it did put out a signal including a test tone but it was kind of weak unless I touched the large N-type RF output plug with my hand then the signal came in loud and clear...

[Polaraligned]

Originally Posted by vortalexfan

I'm actually working on the signal generator that doesn't have the digital readout right now, and for some reason when I hook my stand alone frequency counter up to it, it doesn't register on my frequency counter, and when I used it to "radiate" a signal to my Zenith Royal 2000-1 radio it did put out a signal including a test tone but it was kind of weak unless I touched the large N-type RF output plug with my hand then the signal came in loud and clear...

Well, signal generators put out a low amplitude signal. Turn up the amplitude on the SG all the way and turn up the sensitivity on the frequency counter.

[vortalexfan]

Originally Posted by Polaraligned

Well, signal generators put out a low amplitude signal. Turn up the amplitude on the SG all the way and turn up the sensitivity on the frequency counter.

Alright I'll give it a try.

[ChrisW6ATV]

You can get a telescoping whip antenna with a BNC connector and a swivel at its base for a low price from Amazon or other sellers, and an N-to-BNC adapter, to radiate in-house signals from the generators, convenient for various tests.