Hans
I put two back-to-back silicon diodes across the relay output to my
receiver as overload protection.
73, Tom G3OLB
In message <[email protected]>, Hans-
Albrecht Haffa <[email protected]> writes
p {margin: 0px}
Dear Lowfers,
just I am designing a TR-switch for my new TX. Estimated Power
about 60dbm/60 Ohm.
The current situation with my TX 70W/60 Ohm:
The RX-Path is swiched via two reed-Relays (homemade coaxial ones,
for qsk operation) to the receiver input, the TX-Path is switched
via a reed-relay to the PA both from the common input of
low-pass-filter, whitch is allways in the aerial path. My RX is an
EKD 300 (Funkwerk Köpenick, late DDR). In transmit operation this
will cause an sidetone with an pretty high volume, but not too much
annoying noisy.
My experiments with an 1 Watt driver circuit:
The signal Path: Oscillator - Driver 1 Watt - Attenuator switchable
0d B...50 dB - TR-relays - RX-Input
TR-relays is a series of one Vac-Relay and three Reed-Relays (2
spst, 1 spdt).
All build up with coax connectors. It seems to be that I am still
far away from a S9 signal durig transmitting, even with this 1
Watt-Driver.
How You have solved this task? What is done in commercial equipment
with similar power?
Is it necesary to have anyway a mute circuit for the receiver? An
input voltage of 1 Volt will not be dangerous for the RX-input and
cause some distortionin the audio-signal, but for a sidetone this
is not a problem.
Waiting for reply
55,
Hans-Albrecht Haffa
DK 8 ND
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