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Old December 16th 04, 03:26 PM
Scott Dorsey
 
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TW wrote:

Quoting from the Vectronics VEC-1220K 20M transmitter kit manual, page
26: "Receiver Hook-up: You may patch most receivers directly into your
VEC QRP-CW Transmitter's receiver jack without risk of damage.
Transmitter output is typically around + 32 dBm and the energy
reaching your receiver through the T/R switch is normally 25 dB lower,
or about +7 dBm. This is a very strong signal, but a high-quality
receiver with a wide AGC range can usually handle it without blasting
out the speaker! If you are able to leave the receiver on during
transmit, you'll enjoy the benefit of full QSK operation."


It would strike me that if you really wanted a full T/R switch, and you
did not want to spend the five dollars or so for a fast relay, you could
probably build an acceptable switch using 1N4007 diodes. I would think
that with these current levels at HF that there would be no need for a
fancy switching PIN diode.

Another alternative, by the way, is just to use a vertical for transmitting
and a horizontal dipole for receive. This also has some major benefits in that
your receiver noise will be lower with the horizontal and your transmitted
signal will be slightly better with the vertical.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."