[Elecraft] QSK? Newbie question

[Vic Rosenthal]

Ron D'Eau Claire wrote:
> I remember seeing pictures of those keys, but never saw one in Amateur
> operations. I suspect that was because everyone was used to the fairly long
> delay for the change-over. Well, not EVERYONE... There were groups of ops
> who did work QSK, but they tended to be exclusive little groups since most
> ops couldn't.  Maybe some of them used the same mechansim.

Many ham traffic handlers in the '50's (and earlier perhaps, but it was 
before my time!) used full, "hear-between-the-dits" QSK.  The first 
problem to solve was silencing the transmitter on key-up.  Some had 
transmitters with keyed oscillators.  Direct oscillator keying gave you 
a choice: you could key it without shaping and have a clicky signal, or 
you could shape the keying a bit to avoid that and then you would chirp! 
  At least on 80 meters, where most traffic handling took place, you 
could get an almost-decent signal.

Timed-sequence keying, where pressing the key turned the oscillator on 
first and then activated following stages after a delay was a feature of 
some of the better commercial equipment (e.g., the Johnson Ranger), and 
became popular in homebrew rigs as well.  My own homebrew rig had a 
whole row of pots to adjust various aspects of shaping and timing. 
Hetrodyne VFO's existed in the literature but were rare in actual use.

The next problem was switching the antenna between TX and RX.  Antenna 
relays tended to be too slow to follow keying, so the electronic T/R 
switch was used.  This was usually a tube with the grid connected to the 
plate circuit of the final amplifier or to the antenna; when the 
transmitter was on the grid would be driven negative, cutting off the 
tube.  Output to the RX could be taken from the cathode or plate circuit 
of this tube.  There were lots of complications, but this could be made 
to work smoothly even with high power.

Finally, you needed to mute the RX and inject sidetone.  I used a 
mercury-wetted relay which opened the cathodes of the RF and mixer 
stages in my National NC-101X receiver, and connected the output of a 
neon-tube sawtooth audio oscillator to the input to the AF power stage. 
  The relay was keyed first by my bug, and then later by a series of 
keyer circuits, culminating (about 1962) in the great W9TO circuit.  My 
TO keyer was built on a 10-1/2" relay rack panel, but that's another story!

Vic K2VCO