Topband: Detuning Xmit Antenna while RXing.

k6se at k6se at
Sat Jul 26 21:21:44 EDT 2003

Ernie, KS4Q wrote:

"I'm running an FT-1000MP here and am experimenting with various receive

Can anyone point me to a circuit that I can construct to drive a vacuum
relay to unground my Xmit antennas on Xmit....or ground my Xmit antennas
on Receive as it may be."
Simple.  Just use the TX GND jack on the MP's rear panel with the rear
panel LIN switch in the ON position.  It provides ground when
transmitting and is open when receiving and can be used to
energize/deenergize the vacuum relay.

If you also key your amplifier using the TX GND jack, make sure you use
diodes to isolate the amp and vacuum relay coils from each other to avoid
any relay coil voltage conflicts between the amp's relay and the vacuum

You'll need three conductors going out to your vacuun relay: A wire for
the relay coil voltage, a wire from the TX GND jack and a ground return

I don't know how fast your vacuum relay is, but with this configuration I
would stick to non-QSK operation on CW.

73, de Earl, K6SE

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