[TowerTalk] Elementary Rx protection question

Avery Davis wb4rtp at mindspring.com
Mon Jan 14 00:26:08 EST 2013


Pete
Many, many years ago, I used a separate receiver and transmitter, along
with separate antennas for receive and transmit instead of using a T/R
switch.  To protect the receiver from the very strong signal from the
adjacent transmitter antenna, I placed back-to-back diodes (I don't
remember if they were 1N914A or 1N4148A) at the receiver antenna
terminals, and this worked very well for me.  The receiver was a
Hallicrafters SX-111 (all tubes) and the transmitter was a Hallicrafters
HT-37 (about 100W).  I was pleased with the receiver performance in this
configuration.  Installing the back-to-back diodes was easy with this
receiver since it had two screw terminals for the antenna connections. 
Ultimately, I did incorporate a T/R coax relay so I could use just one
antenna, which improved my receiver peformance because the transmit
antenna was better than what I had been using for a receive antenna.  
For a more modern solution, you might look at an RF component vendor
like Mini-Circuits for what they have in the way of limiters.

73,
Avery, WB4RTP


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