G'day Ken.
Hope you changed your pants.
I just looked through my manual for the Clipperton L and it makes no
mention that you shouldn't do what you just did. It has a number of
warnings but not that one.
Looking at the power supply circuit, I can't see that any damage
would be caused by switching from ssb to cw or vise versa, whether
the amp is keyed or not. I do it all the time on my home brew
3-500Zamp which has the same sort of hv power supply.
The only possibility that I can see is that your mode switch was
indeed faulty and you somehow had both taps switched at the same
instant which would have shorted the high voltage portion of the
secondary to cause that big bang. You say that your voltage is now
lower. You may have some damage like shorted turns somewhere on the
secondary winding that was shorted. Check your transformer first and foremost.
Your filter caps may be on the way out but I reckon this is a normal
thing for an amplifier of this vintage and I don't think this is in
any way related to your underwear soiling event.
73, Alek
VK6APK
At 06:08 AM 15/12/2009, Ken Bessler wrote:
>I recently did a big NO-NO with my Clipperton L:
>
>I switched the mode switch on the L from SSB (2700v
>on the plates) to CW-X (1900v) while the amp was
>keyed. D'oh!
>
>Bang went the amp.
>
>After a few Q & A 's with a local amplifier guru and the
>Dentron (Yahoo groups) reflector, I pulled the HV electrolytics
>and diodes from the HV supply for testing. All the Caps
>showed typical self discharge rates (a day or so) when
>charged with the biggest DC supply I have (30v) EXCEPT
>the cap closest to the output end of the HV supply. That
>cap shows a 80% self discharge after only 1/2 hour.
>
>The diodes (1n5408's) all checked out on 2 different diode
>checkers and 2 different DMM Ohm meters. Typical fV of .570v.
>
>So, I have a bad cap. They are Mallory 125uF/450v snap-ins
>that were soldered in. Given the fact that the diodes are 1n5408's
>and the caps' design I suspect that the board has been rebuilt.
>
>I could be wrong....
>
>The wafer switch (MODE) is salvageable - it arced of course but
>the wiper that arced was poorly aligned so only the edge got burnt.
>I cleaned the switch and realigned the wiper and it now looks very
>good and shows no electrical issues.
>
>Now - on to the Bias Zener, a 9.1v/50w job that my friends
>suggest may have gotten zapped. How can I check that? I
>tried a DMM ohm meter and the ZD shows open both ways.
>I built a test circuit with a 10 w, 3 ohm power resisitor and my
>Astron 20A PS. I hooked the negative to the Anode of the
>zener and the positive through the resisitor to the cathode.
>
>This represented 13.8v/1.32a/~18w into the 50w zener. Instead
>of showing 9.1v, it read 9.48v. I increased the resisitor to a 1.5
>k and the voltage dropped to 8.85 volts.
>
>Am I doing this right with the Zener tests? I can't power up the
>amp because the last time I keyed the amp (no RF in) it smoked
>the 220/110v jumper on the back of the amp, then popped a
>15A fuse, violently. (BANG BANG BANG BZZZZZ POW).
>
>Another fact - before this my HV was at 2700v with a 249v supply
>- after the initial dumb act with the HV switch it dropped to 2350
>V unkeyed. The chinese tubes installed a year ago were half gone
>(600 w pep out on 80m max) already. So, I need a good matched
>quad set of 572b's, a bank of 8 HV caps and MAYBE a new Zener.
>Nobody said amplifiers were'nt cheap.....
>
>Also what kind of fuse should I be using with this amp?
>
>Sorry if this has been long but I wanted to make sure anyone who
>has advice for me has all the pertinant facts.
>
>Thanks all!
>
>
> 73 de Ken KG0WX - Kadiddlehopper #11808,
>Flying Pigs #-1055, Grid EM17ip
>
>
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