Re: Back from vacation


 

Hi Allen,

If you are serious about troubleshooting and repairing scopes you should get yourself a Tek curve tracer. Based on your post you would probably have the most fun with the vacuum tube based 575 transistor curve tracer which you can find in Craig's List for ~$50. But it doesn't really matter which one you get. If you already have a curve tracer I know you are serious about what you are doing.

The good news is for about $100 more you can add the capability of testing vacuum tubes to any Tek curve tracer. It is simple. You may have missed it but about 9 months ago I stumbled on a clever, inexpensive, way to test almost every vacuum tube (and definitely the ones in Tek vintage scopes) by displaying a full set of characteristic curves on any Tek curve tracer. The curve tracer will still test semiconductors because no modifications are made to the curve tracer.

I wrote a paper describing how to do it and I made some PC boards with my adapter design. The very latest and most complete version of the paper I wrote on my Vacuum Tube Curve Tracer Adapter is always located at

http://www.ke5fx.com/A_VTCT_Adapter_for_All_Tektronix_SCTs_W7PF.pdf


Dennis Tillman W7PF

-----Original Message-----
From: TekScopes@groups.io [mailto:TekScopes@groups.io] On Behalf Of kb6nax
Sent: Tuesday, December 19, 2017 2:10 PM
To: TekScopes@groups.io
Subject: [TekScopes] Back from vacation

I bowed out of posting to TekScopes a few years ago because of the dearth of vacuum tube 'scope postings. More recently I've become a fan of Tek 455 'scopes. For 465M lovers the too models have identical power supplies. 455's frequently appear on the 'bay and I've bought a few "for parts/repair" units and now have eight restored. Two to go with bad HV supplies that are now guinea pigs for building from scratch replacement HV multiplier modules. Both the scopes appear to have good transformers and will produce +95 volts when run with a module that has the 3x multiplier disconnected. I've been on and off that project for about a year now but when time is available I continue to solve some of the riddles of how to make a good module. I'm about to construct a breadboard to tackle the mysteries of the bias clamp circuit. The 3x multiplier will be outboard and far enough to avoid getting zapped by 10KV, If anyone is interested I'll post my progress/results.





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Dennis Tillman W7PF
TekScopes Moderator

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