Anyone here like old oscilloscopes? I was wandering through this used electronic parts store's yard today and found a really old one sitting in the rain, and I had to rescue it. "Dumont Cathode-Ray Oscillograph" model 274, it uses the 5BP1-A crt. It looks at least 1940s. It uses two #80 tubes, I don't know when they stopped using those old tube designations, but I thought it was sometime in the 30s. Despite being out in the rain it is actually clean inside, but it uses some capacitors for which locating replacements would be nearly impossible: 5mfd at 1500volts and such. I don't really need another working one anyway, I might just put this ontop of a TV and look at it.

I really hate to do this...but... :worthless

Anyone here like old oscilloscopes? it.

Hi
I Like my Oszi, but i do not no anything about ....

http://audiokarma.org/forums/attachment.php?attachmentid=26269&stc=1

looking for Manual for this mine :)

Helge

Heh
I like the old Tek 500 series stuff. It...just...works...

Would love a good scope cart for my 545A. And get a 580 (they NEED a scopecart!) or a 547...

I had a DuMont that looked like it came off the ark; sold it for about $3 at the ETF convention last year. I got rid of most of my old scopes as they were just taking up space-right now I have an EICO, I think there is still a Bell+Howell school scope somewhere hiding, plus a little RCA from the early 70s that I keep on the bench. I'm no good with them-yet. I do have one other, which I need to keep. It's an RCA, pretty early, which was resprayed with silver paint. Under the paint you can read the old lettering-"NBC TV, Washington". Like all the others, it works at least to the point of putting light on the screen.

I have a Tek 535, an early production one from about 1955. I had intended to restore it slowly as I had time. It worked when I got it, after a little recapping, it works perfectly. Since it got here, I havent used anything else. The "modern" scopes are gathering dust now...

John

I have two 535's one early and one late production. The late one is operational but the early one had one of the wafer switches burn up. It does work but the trigger is now fixed. I got the early one when I was in high school in 1977 so I will keep it maybe some day I will find a parts unit. They are handy in winter to use as space heaters. Tube scopes can be handy when working on high voltage devices, the input stage tubes can take a boo boo better soild state scopes. I've had to repair a few front ends on soild state scopes so I have a few small tube scopes to use if I'm working on something that might spike my good scopes.
Steve

I have this Philips PM3230 tube scope. I got two of them from a local school, none of them working properly. One of them looked very good, and the other was dirty and worn. I got the clean one to work and kept some parts (tubes) from the other one. It har 7 tubes plus the true-dualbeam CRT. It works perfectly and looks pretty good too - a nice piece of equipment. I have not replaced any components yet. I tested some random caps, and they tested good, so i left them in.

I have a Tek 545(A?) -- I can't find a picture of it at the moment :-(

I've got an RCA Cathode Ray Oscillograph (!) from 1935-uses a 1" metal CRT, & a Waterman Pocketscope from right after the war. Neither works, they light up, but that's about it..Would like to get 'em both geein' & hawin' again...-Sandy G.

I haven't kept anything that didn't have a triggered sweep, having worked with MANY scopes that didn't. I'm STILL sick of Lissajous patterns, even though they can be extremely accurate on matching frequency and phase.

I have had intimate introductions to the HV on some of those older scopes.....

That said, even though the trace isn't as sharp as some of the older scopes, the Tek 464,466 storage scope traces are sharp, and the 465's and 475's have a passable trace.I also have had the HP 17xx scopes, keeping a 1726 currently.

I have a complete but not working tek 535

it is getting a little rusty in my carport

I should rescue it - I think I hear it calling to me.

I've got an RCA WO-56 from around '52 or '53, not working. I'll get around to trying to fix it one of these days, but I have a suspicion the power tranny might be bad...

I have had intimate introductions to the HV on some of those older scopes.....

IIRC, they were built the opposite of a TV, with the faceplate at ground and the cathode floating at (minus) high voltage...

IIRC, they were built the opposite of a TV, with the faceplate at ground and the cathode floating at (minus) high voltage...

Well the filament and the cathode are usually at or near the same potential so there is always the problem of moving a few watts way "uphill" to get that filament to glow.

Did some 1" electrostatic deflection crt work for some military apps, and it was preferred that whatever voltages were used, that the electrostatic deflection plates were closest to ground potential, thus like tek we had -2kv to the cathode, and an isolated filament that we had to pump a couple of watts up to -2kv to light the filament, then we had the anode at +5 kv (tek 4xx is +15kv??).

That's when I started to like magnetic deflection in crt's.

I don't remember how the old eico's etc that I worked with were set up.

I've been "bit" by scopes, lasers and whatnot... (over 30+ years) the most memorable (to others, I don't remember much) was the laser start circuit that arced through a supposed insulator.....

I have a Dumont 274-A Catghode Ray Oscillograph in perfect working condition! White picture tube with green trace beam. Very fun to use. I actually use it regularly when I am working on projects. It may be dated, but it was good enough to use in the 1940s so it's good enough now. I see no need to upgrade and am quite happy with it!

The only bad thing about the 500 series teks, besides the weight, and the noise and the heat and Tek's non support, is the screen glows BRIGHT at night. Wake up, freak, scream, then realize it's the darn scope....

I still like 'em though.

Mine's got a scope cam, Polaroid. Don't misload one of those, or it's MESSY

hmmmm... I don't sleep with my oscilloscope (or any of my equipment, for that matter)

;-)

I have a spare CRT for the earlier mentioned Philips scope on the shelf over my bed, and that glows at night too! And so does my TV. But the scope tube is brightest.

I have a couple of old scopes, a Triumph 830 Oscillograph-Wobbulator ( http://antiqueradio.org/trium01.htm ) and an RCA WO-33A ( http://antiqueradio.org/art/temp/RCA_Oscilloscope.jpg ).

Both of them work, although I own them just for fun. When I need to use a scope, I have a modern BK Precision.

I ran across an ancient 5" DuMont scope at a hamfest a couple of weeks ago. Huge, heavy, steel rail frame. I almost grabbed it, then had an attack of common sense :) (Wish I'd have thought to grab a photo of it though.)

--Dave

I ran across an ancient 5" DuMont scope at a hamfest a couple of weeks ago. Huge, heavy, steel rail frame. I almost grabbed it, then had an attack of common sense :) (Wish I'd have to grab a photo of it though.)

--Dave
I had an old silly-scope I dumpster dived. There are a bunch of great old Knobs on that sucker that I cannbalised for old audio gear.I threw the ray tube and the steel case away-especially after I found a big ol patch of Asbestos in there-that stuff causes cancer in labarotory.Rats!

I ran across an ancient 5" DuMont scope at a hamfest a couple of weeks ago. --DaveWhen still in my early/mid twenties there was a "Huge, heavy, steel rail frame" Dumont scope with a 1-microvolt vertical sensitivity setting I used to check the residual noise of mercury batteries that supplied reference voltage to mandrels (sp?) in plotters. IIRC, the scope had a 100-kc vertical bandwidth. After cutting my teeth on 545's with CA plugins, it was quite an impressive hi-sensitivity performer.

The trick to getting a CA plug in to work is to either let the scope sit for an hour or so, or sim ply pull the CA out and put a 1A1 in :)

The CA's best feature is you can't kill it. It otherwise drifts all over the place like John Kerry..

Heh
I like the old Tek 500 series stuff. It...just...works...

Would love a good scope cart for my 545A. And get a 580 (they NEED a scopecart!) or a 547...

I have an 547 that I got in '88, It's Ex Australian army & was made in '64 & it is still in service in a TV repair shop used to align tape paths on LG vcrs.

I have a Philips PM3226 Dual Trace w/Power Cord, 1 set of probes plus Coax and fittings on the way to me for $48 (hope it works) :scratch2:

Here's a Philco made in 1939 specifically for TV:

http://www.earlytelevision.org/early_test_equipment.html

Here is my old RCA scope that just sits around for decoration. It did have a trace at one point, but the cord is telling me not to plug it in right now. Not sure of the date, but pre-war is suspected.

Dave A

I have a Tek 535
John
http://audiokarma.org/forums/attachment.php?attachmentid=10335&stc=1&thumb=1
I had one of these about 11 years ago, but I gave it away. Posted a notice on a usenews newsgroup "free Tek 535 scope with a ton of plug ins, come get it out of here. First email claims it." I was happy to gain a few cubic yards of space, the guy who came was happy to get it. :banana:

BTW, I found that i still have a "Type 80 Vertical plug in". Somewhat incomplete, and the external probe I don't have. Anyone want it (cost of postage gets it)? You could build something custom to fit your scope with it.

I have a modern 400Mhz Tek scope when I need to look at a waveform.

I picked up a Tek 515 today. Its working, and I may use it until I can find a good dual trace unit. I like the look of these old scopes. Probabyl not the best for modern equipment, but good for old TV sets.

I was told it was used in a classroom environment and it has been well cared for. No rust anywhere.

Thats nice! :thmbsp: You may find you don't need dual trace much. As you say, should be good for TV work.

John

I have tripple trace-three late 1950s TV servicing oscilliscopes that work!!!. I have two others that need work, so I could possibly gave a 5 way trace someday. Takes up a lot of space, though.

I've got an early 60s Tek RM-15 that I've had since 1980, when an instructor at my college gave it to me. Rack mounted, and the ratings are nothing special, but when my other scopes have let me down, the old TEK has been there to save my butt. It's only rated for 15 Mhz, but the waveforms seem pretty accurate to 25 Mhz, as long as you don't need to measure voltage. Single trace, single time base, but stable as a rock, and the focus is so sharp you could cut yourself on the trace. And like almost all of the Tektronix scopes of the day, it weighs more than my wifes car. Since I got this one, I've had 2 RCA scopes, and a Leader die, and my Sencore just isn't as nice to use. I also have a 100 Mhz Kenwood scope, but when it dies, I'm sure this old boatanchor will still be plugging along.

I also have an early 1980s dual trace Tek scope. It was sitting on top of a B&K TV analyst (which has several tubes and gets fairly warm) that was powered up. The heat from the analyst killed it and I have not tried to fix it.

The old TV scopes are tube type and much more rugged( but with less features and bandwidth).

I just noticed I never put up a picture of the old DuMont scope that I started this thread with. So, here it is along with the Tek 545A that I use.

Here's my HP H12-175A scope. It's a military surplus scope that I bought at a garage sale in Lincoln, NE about 10 years ago for $20. It's been a great instrument, and still works extremely well. It still has the "property of US Govt." tags on it, and was last officially calibrated in November 1970. It's CRT is also one that has an eerie glow in the dark.

One i got from CarlV (Thanks again Carl!), it's going to get new caps, and be used to provide a "Light show" in a tube amp setup. Might even try to find a second one and do one on each channel!

A couple of shots of it in action. Its really tough to get these pics we discovered... :sigh:

I do it like this: Get it focused real nice, turn the lights off in the room, turn the intensity way down, a little too dim for good direct viewing, shoot.

I do it like this: Get it focused real nice, turn the lights off in the room, turn the intensity way down, a little too dim for good direct viewing, shoot.

Ah, but you have a steady wave form to shoot, I was trying to show the audio signal "light show" and the sig is bouncing to the beat.

One i got from CarlV (Thanks again Carl!), it's going to get new caps, and be used to provide a "Light show" in a tube amp setup. Might even try to find a second one and do one on each channel!

I forgot to say what this guy was: it's a mil spec navy general purpose scope. Very small, (the case is very near the size of a 50 cal ammo box) and this one is made by Jetronic Industries. I'd guess end of WWII or Korea era? The scope even has a sliding shroud to provide shade in sunlight so you can see the beam/trace.

Seems to be completely operable, but gets that hot electronics smell when It warms up, and has several very old 'lytic caps that I'm sure need changing.

For general shop work, I use a Tek 547 with a 1A1 plug-in that I bought freshly serviced and calibrated from a vintage test gear restorer. I've had my 547 since '93 and periodically lift one side of and re-form each of the 'lytics with their rated working voltage and a 20K/5W series resistor just to make sure they're in good shape. My first scope as an experimenter and student was an old Jackson CRO-2. Just before I bought the 547, I was using a 531 that I bought from a TV repair shop. I started using Tek scopes exclusively in college. I learned from working as a lab tech for the university for 2 years that Tek scopes are virtually indestructible and will last practically forever with reasonable preventive maintenance.

For applications where I need more bandwidth or where the 547's size and weight might be an issue, I have a Tek 475A with the DM44 option. I prefer the extreme durability and ultra-sharp trace of the 547, but the 475A's portability is a plus at times. I've had very few problems with the 547, especially considering that the unit is older than I am. I've replaced one tube and one transistor in the time that I've owned it and those two breakdowns were preceded and followed by 4 or 5 years trouble-free. The tube and transistor failures were also both caused by rough handling by movers, as both problems popped up a few days after setting the scopes up in new locations after a move. If I don't re-form the 'lytics every 2 years, I've noticed that it will eventually start blowing the line fuse after an hour of run time until I re-form them again, then it can run for 8 or more hours at a time without blowing its fuse after the caps have each been re-formed to the point of drawing less 1/5(sqrt(C*V)) uA of DC leakage current. For a 125uF/350V, for example, that's 42uA or 837mV drop across a 20K series resistor. At that leakage current, the cap will dissipate 14.7mW due to leakage resistance at rated working voltage.

Anyone know why Tek specifies a 6.25A slo-blo fuse for 115V operation and 3.0A slo-blo for 230V instead of 6.0A and 3.0A?

It's hard to top the old Tek scopes for servicing and analyzing tube systems. With the 20V/div deflection factor available on most plug-in units and a 10x probe, waveforms up to 2kV p-p may be displayed, and slightly larger amplitude waveforms may be applied without risk of harming the scope. Large deflection factors are a must for viewing waveforms in the output stages of tube audio gear. Now, if I could just find a Tek 570 for under $1,200. For the newcomers, the Tek 570 is a Curve Tracer similar to the Tek 575 Transistor Curve Tracer, but designed for displaying vacuum tube characteristic curves.

Included here are some 1950s-era pictures of two unusual scopes (from an old Howard W. Sams book on oscilloscopes). The Probescope PO-1 had its 1" CRT mounted inside the probe housing. The three pictures of it include a view of the semi-portable instrument showing the scope's front panel, close-up of the probe, and then the PO-1 in use on what appears to be one of Motorola's B/W chassis similar to the one which was used as the starting point in the evolution of the design which became their 19" color set.

In my travels in the world of vintage TV, I've learned that Motorola modified a chassis design originally intended for a 24" B/W set, adding the chroma and convergence circuitry on a vertically-mounted subchassis attached to the rear of the main chassis and using a voltage-multiplier and regulated HV supply. An odd type of regulator tube called a Victoreen tube, which used controlled internal corona discharge to provide passive shunt regulation for the HV instead of the active shunt regulation provided by, for example, a 6BK4 high voltage triode, was used in early Motorola color sets.

The next unusual scope pictured here was known as the Kingston Absorption Analyzer, which used a capacitive pickup device as its probe. A turret-type TV tuner inside the unit allowed for restricting the instrument's passband to selectable presets. Looks like a roundie color set is being serviced in the pic. If that's an RCA, then the horizontally-mounted chassis and "afterthought" appearance of the dynamic convergence subchassis suggests it might be a 21-CT-55 aka CTC2B, which was an update of the CT-100's CTC-2 chassis, modified to use the 21AXP22 CRT in place of the 15GP22. Let's hope that classic has survived and is safely stored away somewhere cool and dry, yet to be rediscovered. Just a reasonably-educated guess on the identification of the pictured roundie. Can anyone who actually owns a 21-CT-55 or has seen one recently confirm or correct my guess?

The next unusual scope pictured here was known as the Kingston Absorption Analyzer, which used a capacitive pickup device as its probe. A turret-type TV tuner inside the unit allowed for restricting the instrument's passband to selectable presets. Looks like a roundie color set is being serviced in the pic.

During one of my at-least-once-weekly in-person tech-talk sessions with Big Dave since he's moved back into Warren from Columbus, he and I solved the question of conclusively identifying the color roundie pictured with the Kingston Absorption Analyzer scope in my post above. It's an Admiral model 29AZ1. We identified it by examining cabinet rear view photos in Sams documentation for several early color sets, by searching for the color-coded folders in my Sams library (since Sams used pink folders to identify color sets during that era) until we found the one whose cabinet rear view matched the pic.

Regarding old scopes, I'm still using that Tek 547 or the 475 depending upon the features needed for accomplishing a particular task, but I've also started using an 80s-era B&K scope (due to super-small size and weight and very sharp and bright trace) for projects requiring an ultra-portable unit and where a general-purpose recurrent-sweep scope of about 5 MHz bandwidth is adequate. It's especially handy for RF/IF alignments where its tiny size allows placing the scope in the most convenient position to allow viewing changes to a response curve while keeping the area of the chassis where I'm working well within my field of vision.

A couple of favorites from my scope collection:

http://www.myvintagetv.com/oscilloscopes/sm_rca_151.jpg
- RCA 151 1" CRT

http://www.myvintagetv.com/oscilloscopes/sm_national_cru.jpg
- National CRU 2" CRT

Here's a link to some of my collection of early scopes, I only collect scopes with 1,2, or 3 inch tubes.
http://www.myvintagetv.com/vintage_test_equipment.htm



Still looking for one of these, General Radio Model 497:
http://www.myvintagetv.com/Scope/GR%20497.jpg



Chuck

That little National is one cute scope...didn't know they made 'em!

http://img.photobucket.com/albums/v223/mhardy6647/scopz.jpg
http://www.audiokarma.org/forums/attachment.php?attachmentid=147642
http://www.audiokarma.org/forums/attachment.php?attachmentid=148264

In the buildings of Bucharest Univerity, besides the History Faculty (where I'm studying) tehere are also some other facultyes - including the Chemistry Faculty. About one year ago they dumped some thing - including an '60's East-German (G.D.R.) Made "R.F.T." Dualscope. Unfortnley, I din't have money to give to the ones that where sopoused to desmentle it (in Romania it's a stupid law that sayes that old equypment must be destroyed after it's getting out of use), and another guy whom I called to get it wasn't intresed. Shoot, and there aren't so many tubes (valves) oscilloscopes in Romania :tears:

I got a heathkit IO-12 .
Seems to work pretty good , I done a bit of a recap on it .
I still have to get a demodulator probe for it one of these days .