I use a surplus coax relay, one with BNC connectors, and it is triggered
from the KEY OUT function on the transceiver along with the 12V
source. Be sure and use a diode across the relay coil to prevent back
EMF. The relay switches the RX ANT port to a 50 load, being a resistor
mounted in a BNC connector on the N.O contact port. The common relay
port goes to the radio RX ANT IN and the N.C. relay port goes to the
transceiver RX antenna. It only clicks when the PTT is active and
released. As to CW, well that's another issue where the relay needs
to be held in during transmission or you'll hear it with every CW element.
I personally would be concerned about using solid state switching
devices in as much as a junction when saturated may be prone to produce
harmonic related energy. However, there are circuits which use PIN
diodes or JFETS, designed correctly, would likely be clean.
73
Bob, K4TAX
On 2/1/2020 4:48 PM, Don Wilhelm wrote:
Ray,
Your transmit signal is getting into your RX antenna with more energy
than is safe for the K3S. 10 meters is not much separation unless the
antennas are oriented so one is not in the null pattern of the other.
Using antennas that are of opposite polarization (such as a horizontal
dipole and a vertical) may be OK for a 10 meter separation, maybe not.
There are protective devices available that will disconnect the RX
antenna when the K3S is transmitting, and use of one of those may be
the quickest and easiest solution.
73,
Don W3FPR
On 2/1/2020 5:21 PM, raycollins wrote:
My K3S is configured to use the RX ANT IN port for a separate Rx
antenna.
However, on SSB transmissions I can hear an internal relay operating in
synchronism with peaks in transmit power. I assume this is a relay
in the
receiver input protection circuit?
Is operation of the relay in this manner normal? Apart from finding the
noise rather irritating I am concerned about the reliability of the
relay
when it is called upon to operate so many times during a QSO.
The Tx and Rx antennas are about 10 metres apart and I am
transmitting 100
Watts.
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