[Boatanchors] Electronic TR Switch?

[Glen Zook]

A low pass filter can help with TVI.  Unfortunately,
it does nothing for interference to other amateur
radio bands and for the harmonics that fall outside of
the amateur radio bands but are below the cutoff
frequency of the filter.

It doesn't take much energy on a harmonic to be
radiated thousands of miles, especially the odd order
ones (3rd, 5th, etc.) on which an antenna is also
likely to be resonant (i.e. 3/2, 5/2, and so on).

A tube type TR Switch is quite likely to cause
problems by generating harmonics that will interfere
with both amateur radio communications and other
services as well.  Not every TR Switch will cause
problems but a very large percentage will emit
harmonics.

Glen, K9STH


--- Vic Rosenthal <vic at rakefet.com> wrote:

And the solution, then and now, is a lowpass filter
between the tr switch and the antenna.  The mechanism
that generates harmonics here is exactly the same as
the one in a class-C amplifier.

Glen, K9STH

Web sites

http://home.comcast.net/~k9sth
http://home.comcast.net/~zcomco

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