[Elecraft] Short QSO's (was Re: 6M CW)

[Tom W8JI]

> The Johnson T-R switch came in two iterations, as I recall.  The first
> one suffered from suck-out, as did the second, but less so.

Signal suckout occurs because the tank circuit in the transmitter presents a 
low impedance when the tube end of the tank is misterminated during key-up 
(resting or receiving) periods. Remember a tank circuit is also an 
artificial or lumped transmission line that often looks like it is 100-140 
degrees long electrically, so the impedance at the end going to the 50 ohm 
cables can be very low when the tube is not conducting..shorting the 
transmission line for received signals. If you would have added around 40-80 
degrees of extra coax between the rig and the T/R switch tap point it would 
have cured the signal suck-out.

For a very short time I ran my B+ through the second unused blade of my 
knife switch so I could use one 300 volt supply for my receiver and 
transmitter. Good training in eye-hand coordination.