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Protecting an Active RCV'R Preamp

Nov 20th 2017, 23:43

KI7LFD

Joined: Mar 13th 2017, 22:46
Total Topics: 0
Total Posts: 0
I'm interested in using a loop antenna in conjunction with a small SDR receiver in my shack. The loop would be located about 40' from my End Feed wire antenna used with a 100 W transceiver. I'm concerned that the RF from the 100W transceiver would burn out the loop antenna's preamp, which is located on/in the loop antenna itself. All of the devices I've seen that provide protection are located "after' the preamp at the UHF connector or even further down the coax, not protecting the loop antenna's preamp whatsoever.

How can I protect this somewhat independent antenna/receiver system ?

Thanks in advance for the help.

Regards,
Rich
Dec 23rd 2017, 18:06

WA8NVW

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
My first choice would be to drop power to the preamplifier while you are transmitting. Usually those only draw tens of millliamps so #26 wire (CAT5e) is big enough from the shack out to the loop, same route as the receive coax.. If you use a remote relay to do the switching, also ground the receiver's unbalanced RF input for added protection.
You may still need more shielding for the receiver than is provided by the usual plastic housing, in order to reduce the level of 'birdies' coming from your shack computers, internet devices, and home appliances.

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