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Old 17th Mar 2012, 10:44 pm   #101
Radio Wrangler
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Default Re: Oscilloscope Collection / Junky

Hi, my name's David and I'm a scope-aholic.

I started out as a kid in the 60's building home-made scopes. Bits of circuitry were nicked from wherever they were found, other bits were made up as I went along. One version had a 5BP1 tube in a frame made of welded 0.5 by 0.5 inch steel angle. The front panel was a piece of recycled aluminium from a scrap yard. It had part of a coat of arms on it when I got it, it had previously graced the front of a Huddersfield trolleybus. (Sad loss to humanity, they'd be great nowadays) The 5BP1 nested in a plastic flowerpot whose rim formed the bezel and the back step in the rim stopped the thing sliding back through the big hole in the panel.

Later variants used a VCR97, and I bought a tea-chest full of CV138 (EF921) from Jim Fish. In the early 70s I was trying to build plug ind for an advance OS2100 I'd bought in a surplus sale. But before that could happen, I wound up with a job at HP. Designing test equipment!

I did design part of one oscilloscope project at HP, the 70703A modular unit that fits into the HP70000A frame.

HP scopes weren't bad. Their amplifiers were excellent, and the Colorado Springs CRT plant always got finer line focus then Tek seemed to bother with. The timebases were good and linear. It was the trigger which let them down. The 180 family used tunnel diodes and drifted off-song. The 1740 was a good all round 100 meg scope, but the samplers were the jewel in the HP scope range.

What have i got?

Cossor CDU150 on loan to someone who recently went SK

A few HP 180A with various plug-ins

HP 140 with TDR plug-in

HP180 with 8558 spectrum analyser plug in

12GHz sampler/TDR plug-in for HP 180 (never used)

HP1740 (needs 100u 20v tant for slow timbase ranges)

Tek 465B daily user

Tek 465 spare

Tek 7403 mainframe
two 7A26 amps
one 7B53A timebase

The big Tek needs some time spending on it. one amp channel is dead and the timebase seems to have a dead current source for the main ramp generator.


When HP pulled out of linear scopes and everything went for under-sampling digitisers, we engineers started buying Tek 350 MHz jobs. We wanted to see what we were doing!

Tek's founder Howard Vollum invented the triggered timebase. He went to see Bill and Dave and offered it to them. They said they had too much on at the moment and advised him to set himself up in business. I believe they kept in touch provided advice and were genuinely pleased that he was successful.

Business has changed a lot since then.

David
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Old 18th Mar 2012, 11:55 am   #102
6AL5W-Martin
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Default Re: Oscilloscope Collection / Junky

hello,

my next restoration is coming:

Tek 5103N

after 3 pcs. 310A, my first 5k.
greetings
Martin
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Old 21st Mar 2012, 1:22 pm   #103
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Default Re: Oscilloscope Collection / Junky

Just arrived today, 1947 GE. This might or might not end up being a difficult project for me. Hope it's alright if I can ask you all for some advice in the future. Still waiting on a variac. I do have all new tubes including 3AP1A crt.
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Old 21st Mar 2012, 7:51 pm   #104
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Hello Brandon,

The old scope looks very fine, there is no scratchings.

My new old toy is a swob.

Greetings
Martin
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Old 21st Mar 2012, 9:27 pm   #105
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Default Re: Oscilloscope Collection / Junky

Thanks Martin,

I just hope the inside looks as good as the outside. We'll see. There are no available schematics for mine besides from the old Riders, Encyclopedia of Oscilloscopes. Thing is, that schematic has no values. This will be a slow going project. Finding information on mine is very difficult.

Your new toy is also in amazing shape. Very nice indeed.

Regards,

Brandon
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Old 21st Mar 2012, 11:37 pm   #106
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Default Re: Oscilloscope Collection / Junky

That SWOB looks like new. Where do you find them, Martin? But isn't there a missing adapter?

Peter
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Old 22nd Mar 2012, 11:11 am   #107
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Default Re: Oscilloscope Collection / Junky

Quote:
Originally Posted by Brandon_R View Post
Just arrived today, 1947 GE.
That's beautiful, you must be well pleased!

Reminds me, I should post a pic of my newly-arrived 1953 National.

Have also made quite the lucky find recently - a 1960s (or so) Trio kit oscilloscope (built), in the original box with all the original documentation

Ed.
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Old 22nd Mar 2012, 7:54 pm   #108
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Quote:
Originally Posted by dinkydi View Post
That SWOB looks like new. Where do you find them, Martin? But isn't there a missing adapter?
hello Peter,
It`s from the bay, sold as is..

I can be happy, this one is full extendet, it was used by the state.
There is a missing adaptor, N to BNC, not found

greetings
Martin
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Old 22nd Mar 2012, 11:57 pm   #109
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Touche Martin!

Peter
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Old 24th Mar 2012, 4:42 pm   #110
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Default Re: Oscilloscope Collection / Junky

I was able to find the time today to open her up and have a look and start cleaning. I have some recapping to do. Neat to see those old Aerovox type 684 600v caps, but their oily on the ends and should be replaced before I even apply any electricity. NOS Aerovox caps do show up for sale time to time.. I might start looking. Luckily values are still readable!

Look at the wad of caps around the front controls.

Any of you ever melt out old caps and insert new ones into the old then refill with wax? I better search the forum. Sure someone has some pointers on the proper way.

Ed, would love to see your 53 National!
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Old 24th Mar 2012, 5:31 pm   #111
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Default Re: Oscilloscope Collection / Junky

an old MO5, very sick ...

greetings
Martin
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Old 24th Mar 2012, 6:59 pm   #112
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Default Re: Oscilloscope Collection / Junky

at the moment mines dead...

nice old scope you have, probably much more work to get going than mine, mine was not a top end scope even in it's time.
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Old 25th Mar 2012, 4:15 pm   #113
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Default Re: Oscilloscope Collection / Junky

Quote:
Originally Posted by Brandon_R View Post
Ed, would love to see your 53 National!
Happy to oblige with a bit more scope porn for this thread

Now, ladies and gents, is this or is it not the smallest oscilloscope ever made using only octal valves? Answers on a postcard to...

(It's a Japanese scope, so the size reference is of course a can of Japanese beer )

A National CT-50B, as stamped on the spec plate on the front: made in the 10th month of the Japanese year Showa 28. Or to us lot, October 1953 S/N 623.

The front lid is hinged, it does lift out of its hinges though if you need it out of the way.

The direct inputs, concealed behind an access panel on the back, are labelled in Japanese. From left to right they say "Horizontal", "Ground" and "Vertical".
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Old 25th Mar 2012, 4:21 pm   #114
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Default Re: Oscilloscope Collection / Junky

Innards! It seems that most of the components inside were made by Matsushita (National is a Matsushita brand name) themselves.

The National logo embossed onto the end of the big electrolytic is a natty touch

Aug 1953 date codes can be seen on another capacitor (had to play with the settings on this image to make it more readable) and one of the valves.

Ed.
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Old 25th Mar 2012, 9:19 pm   #115
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53 and written in Japanese, awesome

The gec on your website is marvelous! That they could make such a compact valve scope like that..
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Old 26th Mar 2012, 5:49 am   #116
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Default Re: Oscilloscope Collection / Junky

Glad you like them!

Yeah, the Miniscope is quite a piece of engineering. There is a dual-trace adaptor for it (it's another CRT in a box that attaches to the top), but they're like hen's teeth (though at least one user of this forum has one). There is also a wobbulator adaptor, but I've never seen one except in the original print ads.

Ed.
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Old 27th Mar 2012, 5:23 pm   #117
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Smile Re: Oscilloscope Collection / Junky

5103N, with dual inpĆ¼t + diff.
Slowly, but sensitive

greetings
Martin
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Old 28th Mar 2012, 3:10 pm   #118
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Default Re: Oscilloscope Collection / Junky

Martin, is that a 5A22 plugin ?
It seems quite similar to the later 7A22 - a very usefull and reliable plugin althought the DC drift takes quite a while to settle down

dave
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Old 28th Mar 2012, 4:58 pm   #119
6AL5W-Martin
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Default Re: Oscilloscope Collection / Junky

hello dave,

yes, and exactly there I have to do a repair.
The 5A22N dont get the signal, maybe a blown input stage (Dual Fet?)
The 5A18N works allready, 1mV/cm

greetings
Martin
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Old 29th Mar 2012, 11:55 am   #120
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Default Re: Oscilloscope Collection / Junky

The 7A22 has input fuses (at 1/16Amp) - maybe the 5A22 as well ?

Happy hunting !

dave
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