Re: TX-RX switching

Arv Evans K7HKL <arvevans@...>
 

IEA4DSY

My BITX uses NPN's for switching. The 0.7 volt drop didn't seem to bother much, but I am running 13.8 volts to the transceiver and 26 volts to the IRF510 RF PA.

The problem with fast switching is that there are some bypass capacitors in the receiver circuits that will keep the receiver alive for a few ms after the transmitter comes on line.  This causes a "ping" in the audio system that can be quite loud.  This is especially annoying when using VOX to run QSK CW ( inserting a keyed tone into the microphone jack to generate the CW ).

Arv K7HKL

On Tue, 2005-11-08 at 21:59 +0000, ea4dsy wrote:
I am thinking of using a pair of P-channel Mosfets for swithching fast
and without voltage drop and relay coil power drain.





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