[time-nuts] HP-5245L display...

[Burt I. Weiner]

Peter,

The driver lamps in the display magic black boxes consist of neon 
type bulbs.  Like all neon devices, over time they become 
flaky.  Many years ago I had success in replacing some of the neon 
lamps in one of my displays, which solved the problem - for a few 
years.   A side benefit was that I learned some new words and even 
invented a few even newer ones!

I'd also thought about replacing the original display portions of the 
boards.  As I recall, there was an issue with the way the dividers 
and display works and I don't believe they work on decades.  I may be 
wrong on that, but that's what's stuck in the krell of my memory.  If 
you should wind up replacing the nixies and their drivers I would be 
very interested in what you do.  I think the 5245L counters were a class act.

Burt, K6OQK


>Subject: [time-nuts] HP 5245L Question
>
>
>I read the recent comments on the HP5245L with interest. I have 
>several of these excellent instruments and recently used one in 
>anger, to repair a 20GHz Signal Generator (HP 70000 Series) for my 
>employer, thus saving them circa ?10000.
>
>My question is, has anyone experienced the deterioration of the 
>photo cells, another early semiconductor device with somewhat less 
>than a forty years life expectancy? These seem to fail randomly, and 
>I guess it is also a hygroscopic problem.
>I wondered about replacing nixie tubes and associated drivers with 7 
>segment LEDs in one of my (already hacked) units, to make it more 
>reliable. I would use the BCD to drive the display, thus requiring a 
>new interface board to be designed. I wonder if anyone else has 
>considered such a radical remedy to the failing photocell problem?
>
>  In case anyone is wondering 'WHY BOTHER?', my defence is that I 
> too have an extensive collection of the plug ins, extending the 
> usefulness of the basic instrument way beyond my budget for more 
> modern equivalent instruments.
>
>Hope this question is not considered too far off topic for this forum.
>
>Peter Worrall
>G4GJL
>London

Burt I. Weiner Associates
Broadcast Technical Services
Glendale, California  U.S.A.
biwa at att.net
K6OQK