Operation
The TR switch provides switching between two separate sets of contacts to two separate output/input pairs.
It will sense RF input on the TX inputs and switch at approximately 50mW of RF and above and can be used over a
frequency range of 160-6M and up to 125 Watts of RF under matched conditions.
The switch can be bypassed by grounding pin 3 (Bypass) of the control inputs (X1). This will prevent the switch
from engaging either in manual or automatic, RF sensed mode.
For testing, or for manual switching from an external control, operation of the relay can be accomplished by
grounding pin 2 (Key).
12V DC power should be connected at connector SV1 with V+ to pin 1 (marked “V+”) and ground to pin 4 (marked
“G”)
Choice of C1:
Capacitor C1 senses the RF signal and feeds the signal to Q2 to control switching.
The 47pF capacitor supplied for C1 should work over most conditions and is recommended for most applications.
An extra 22pF capacitor is also included and is recommended if power levels used will always be above 50W.
If automated switching is not reliable on certain frequencies, or at certain power levels, the value of C1 may need
to be adjusted.
In general, increase C1 for lower frequency and/or lower power operation and decrease it for high frequency and
or high power use.
Board Connections
The Antenna, RX and TX as well as the second switched pair (C, NC and NO) are as shown above.
Easy TR Switch V3 20171212
5
RX
GND
TX
GND
GND
Normally Closed
GND
Normally Open
Aux.
Antenna
