Virtuiso@aol.com wrote:
>
> I am trying to fix a MLA2500 amp that was zapped on the CY9AA expedition.
> Having little more than a DVM, I am at an impass.
>
> We do have:
> o High voltage on the tubes
> o Filaments (tubes get warm)
> o Relays operating (time delay, T/R)
> o Some cathode voltage
> o Some grid current when excited
>
> We DON'T have:
> o Idling plate current in transmit
> o Any plate current when excited
> o Any output in transmit
>
> The amp went "zap" and quit working, after 3 days of intense use.
>
> I welcome any and all suggestions of what to check next and how and, is it
> down to tubes?
>
> Thanks!
>
> Tom Taormina, K5RC/7
>
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Hi Tom,
I'm not sure if you measured B+ at the tube plate or at the p/s.
Sounds like you might have an open plate choke...in any case, no
B+ on the plate.
Another possibility is the keying circuit is changing antenna/
driver inputs ok but not placing the amp in the TX mode even
though the relays actuate.
This may not be it but its a starting place.
How's it going...been a while since we talked.
73, Bob, W5AH
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
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