Something that appears to have been missed in this discussion of T/R
switching, especially where QSK is involved, is that both
transceivers and amps have delay circuits involved that prevent the
rig from transmitting before the relay has switched. Delays on the
order of 10 ms are typical. When done well, the rig can follow CW at
pretty high speeds without distortion of the keying. Some rigs are
far better than others in this regard, and these characteristics are
noted in QST reviews.
The keying circuit for some amplifiers works "pre-delay" -- that is,
the DC keying from the transceiver to the amp precedes the RF
carrier by 10-15 ms. This delay is accomplished in the transceiver.
Another way of doing it is for all of the keying to be controlled in
the amplifier. With these amps, you key the amp and the amp keys the
transceiver. All of the TenTec amps, with the exception of the
original Hercules, the 444) use this method. That's why I own three
AEA MM-series keyers!
73,
Jim Brown K9YC
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|