50Mhz Oscilloscope Design in Wireless World 1975. - UK Vintage Radio Repair and Restoration Discussion Forum

WME_bill · 19th May 2014, 3:04 pm

George Livanes "oldtech1000" has recently asked me for some info upon the PSU for this design by CMJ Little published over 4 month period in 1975.
I have scanned the articles, as it is quite an interesting design, and for its date, not very far behind the mainstream commercial market.
The full articles are too large to post, but I attach the PSU circuits as he requested.
There were quite a number of interesting articles about Scopes and Wobbulators in WW over the years. A lot in 1950-1960, I suppose when scopes first began to appear commercially. wme_bill m0wpn

audiomik · 19th May 2014, 5:35 pm

built a variation of this design but dual trace using a different CRT.
Learned much about 'Scope internals and used the finished instrument for a while on my bench in the early 80's.

Seem to remember using a pair of transistors to 'create' the Tunnel diode for timebase triggering which worked well, and modifying one Y channel to be fully differential
Mik

Ed_Dinning · 19th May 2014, 8:18 pm

Yes I built this one too, used a scope tube from Smiths of Edgware Rd, true Dual beam type with PDA. It worked very well and I think I still have the tube.

Ed

WME_bill · 20th May 2014, 7:07 pm

50MHz oscilloscope ex W.W. I studied the articles, and planned to build it to replace the valve one I had built from a design in Short Wave Magazine 1955 by A.K.Brookman G3FLP, which used five EF91 and a VCR139A/ECR30 tube, and was very compact indeed. About the size of the Metrovick CT52/84 or Cossor 1039, but a better performance. I spent a whole summer vacation when a student playing around with inductive compensation to improve the frequency response to 1Mhz.
Then I was going to build the WW valve design of 1963/64, but actually had to do some work (earn) at that time. I was given a Hartley 13A instead, which quite distracted me, and then acquired a wife. So though I planned to build this modern transistor design, I never got around to it as I was given a modern Telequipment scope at work.
The first scope you build seems to be the one you learn most about.
As a matter of interest, Audiomik, how did you resolve the alternative Tunnel diode. I'd be interested to see the circuit. Presumably a schmitt trigger arrangement.
And both you and Ed Dinning used dual beam tubes too.
wme_bill m0wpn

ParcGwyn · 20th May 2014, 7:15 pm

I've just ordered a bound edition of WW May to Aug 1975 to have a look at this design it sounds very interesting. I would also be interested in seeing how you created the tunnel diode.

Dave
GW7ONS

audiomik · 22nd May 2014, 10:33 am

for the 'Tunnel Diode', I recall there being an equivalent circuit using two transistors published in another WW article.

This article might shed some light on it?
http://www.vk6fh.com/vk6fh/lambda_diode.htm

Mik

19th May 2014, 5:35 pm	#2
audiomik Retired Dormant Member Join Date: Oct 2010 Location: Bath, Somerset, UK. Posts: 96	Re: 50Mhz Oscilloscope Design in Wireless World 1975. built a variation of this design but dual trace using a different CRT. Learned much about 'Scope internals and used the finished instrument for a while on my bench in the early 80's. Seem to remember using a pair of transistors to 'create' the Tunnel diode for timebase triggering which worked well, and modifying one Y channel to be fully differential Mik

19th May 2014, 8:18 pm	#3
Ed_Dinning Dekatron Join Date: Jan 2004 Location: Newcastle upon Tyne, Tyne & Wear, UK. Posts: 8,195	Re: 50Mhz Oscilloscope Design in Wireless World 1975. Yes I built this one too, used a scope tube from Smiths of Edgware Rd, true Dual beam type with PDA. It worked very well and I think I still have the tube. Ed

20th May 2014, 7:07 pm	#4
WME_bill Octode Join Date: Oct 2007 Location: Exeter, Devon, UK. Posts: 1,554	Re: 50Mhz Oscilloscope Design in Wireless World 1975. 50MHz oscilloscope ex W.W. I studied the articles, and planned to build it to replace the valve one I had built from a design in Short Wave Magazine 1955 by A.K.Brookman G3FLP, which used five EF91 and a VCR139A/ECR30 tube, and was very compact indeed. About the size of the Metrovick CT52/84 or Cossor 1039, but a better performance. I spent a whole summer vacation when a student playing around with inductive compensation to improve the frequency response to 1Mhz. Then I was going to build the WW valve design of 1963/64, but actually had to do some work (earn) at that time. I was given a Hartley 13A instead, which quite distracted me, and then acquired a wife. So though I planned to build this modern transistor design, I never got around to it as I was given a modern Telequipment scope at work. The first scope you build seems to be the one you learn most about. As a matter of interest, Audiomik, how did you resolve the alternative Tunnel diode. I'd be interested to see the circuit. Presumably a schmitt trigger arrangement. And both you and Ed Dinning used dual beam tubes too. wme_bill m0wpn Last edited by WME_bill; 20th May 2014 at 7:31 pm.

20th May 2014, 7:15 pm	#5
ParcGwyn Hexode Join Date: Jun 2005 Location: Aberystwyth, Wales, UK. Posts: 358	Re: 50Mhz Oscilloscope Design in Wireless World 1975. I've just ordered a bound edition of WW May to Aug 1975 to have a look at this design it sounds very interesting. I would also be interested in seeing how you created the tunnel diode. Dave GW7ONS

22nd May 2014, 10:33 am	#6
audiomik Retired Dormant Member Join Date: Oct 2010 Location: Bath, Somerset, UK. Posts: 96	Re: 50Mhz Oscilloscope Design in Wireless World 1975. for the 'Tunnel Diode', I recall there being an equivalent circuit using two transistors published in another WW article. This article might shed some light on it? http://www.vk6fh.com/vk6fh/lambda_diode.htm Mik