> A pair of TexasStar Sweet Sixteens in which the
transformers
> and splitter combiners have been replaced with components
> designed for 160-10M.
>
> Also added is a splitter at the input and a combiner at
> the output.
>
> This is a work in progress guided at a distance by a Ham
> who has done the same thing with the same amps.
Hi Doc,
Those amps are "designed" to be nothing but cheap CB
amplifiers. They have very poor linearity. Part of the
non-linearity issue is caused by the very poor biasing
system they use. This causes crossover or threshold
distortion that generates low level crap out many odd-orders
from the main signal.
The second problem is they severely overrate the output
power of the PA. The PA is well into gain compression a long
time before the output power rating is reached. Part of this
is caused by the bias shifting negative as drive increases,
and part is caused by the devices running "out of steam".
I hope the next big technical problem we face on Ham bands
won't be people bringing CB amps to amateur bands. There is
very little likelihood 12-18 volt devices will produce
acceptable IM performance at kilowatt power levels. I hope
the idea doesn't catch on! 28 volt devices are bad enough.
73 Tom
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|