View Single Post
Old 17th Mar 2012, 10:44 pm   #101
Radio Wrangler
Radio Wrangler's Avatar
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 14,080
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.

Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done
Radio Wrangler is online now