On Thu, 2009-08-20 at 18:11 +0200, F8EHJ wrote:
> Thanks for your explaination,
>
> It is critical to have a high SWR (1.6) because I don't know if it
> is capacitive or inductive load.
>
> 73's
>
> Herve F8EHJ
>
>
The trouble with a high SWR on a solid state transmitter is that the
output matching is not adjustable to present the design load to the
output transistors which can affect the longevity of the output
transistors by causing them to draw too much current (often protected in
TenTecs by the power supply current limiting or having a fast acting
circuit breaker) or to develop too much collector voltage swing leading
to voltage break down in the transistors. TenTec PAs are conservatively
designed, but they will give better linearity and power when properly
matched. Hence the external antenna tuner does what the tunable output
network did for a tube transmitter.
73, Jerry, K0CQ
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