[Amps] AL1200, high input swr, all bands

[Alek Petkovic]

Amplifier input/output relays? Are they making and breaking as they should?

I fixed a AL811 amp once which had the relays cooked. Dunno how they 
do things in the 1200. Knowing Ameritron, it will be just as pathetic.

73, Alek.
VK6APK

At 03:05 PM 18/10/2010, Kevin Normoyle wrote:
>   I must have fried something in my AL-1200 and would be interested in
>thoughts.
>
>Details:
>Was operating on 15M, rtty, when it died. I watch temps with an infrared
>thermometer so I wasn't expecting to have cooked something. Although,
>yeah, of course it's a higher duty cycle than typical (high speed fan
>setting).
>
>No obvious smoke. No obvious smoked or cooked parts inside with cursory
>visual inspection.
>
>Amp's HV meter reads normal.
>No grid or plate current indicated when RF input applied, on any band
>(with known good plate/load settings).
>
>Driving rig indicates infinite swr (all bands). I guess this is the
>biggest clue.
>
>When amp meter is set to ALC, it indicates input RF power which seems
>okay (tracks rig output power?).
>
>I don't see the input pi-network in the AL-1200 schematics, so am not
>sure what's there.
>
>Is there something typical that gets burned out with these symptoms? Or ???
>I was driving it on 15M with more rf than I need on 80/40/20 for a given
>output level, but <100W (maybe 75W?)
>
>Thanks for any thoughts,
>Kevin
>AD6Z
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