Rich says:
> The bottom-line is that there should not be a situation where the
bias
>can be in the non-linear/Rx mode when the RF relays are in the Tx mode.
I must admit that I've never thought it through very carefully before, but
unless the bias is switched before the RF gets there, you must be
effectively pulse modulating. This will give the usual sinx/x spectrum, with
sidebands off to infinity (or at least a long way!) with nulls at offsets
that are the inverse of the rise time. The overall ill effect should be
minimised by having a long hang time, so that it doesn't switch very often -
but it will still splatter while it does.
As an alternative, how about switching the bias by means of a signal derived
from the audio, so the PA is switched before the RF gets there? Sounds a bit
like having relays and interlocks, doesn't it?
And as Rich says, getting switching on 'soft' syllables is difficult. Ever
get a VOX that's really satisafctory, especially on words like 'electron'?
73
Peter G3RZP
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