Dr. Gerald N. Johnson wrote:
> On Mon, 2007-07-30 at 16:26 +0100, Bob Towers wrote:
>> Some time ago the power output on my Argonaut V dropped to nearly zero
>> on all bands.
>>
>> TenTec say the most likely cause is
>>
>> a) one or more of the switching diodes in the LPF circuits
>> or
>> b) blown finals
>>
> Open switching diodes in the LPF circuits could lead to blown finals by
> letting the transistors develop excess voltage when not loaded. An open
> makes a high SWR for the transistors.
>
>>
> 73, Jerry, K0CQ
>
Thanks, Jerry, for your comments.
I'm beginning to wonder whether the finals might be blown rather than
the diodes because the low power is on all bands, not just some of them.
Presumably it's rare for all the switching diodes to be blown.
73
Bob
MM0RKT
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