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RE: Newbie: Noise on RX when keying TX



12/4/00 6:32 PM, Scott Townley at nx7u@arrl.net wrote:

> Sometimes (but not always) when I key my TX I hear about S5 noise
> "feedback".  NB is off on rig (FT-726R).  Often the noise is loud enough
to
> compromise hearing my downlink sig.

	Scott, I have had a similar problem.  Some receiver front ends
and/or preamps handle the strong out-of-band transmit signal better than
others.

	I found a quarter wave open stub, cut for the transmit frequency
(435 MHz), at the input of the receive preamp (145 MHz) almost completely
eliminated the problem for me.  The quarter wave open stub will look like a
short circuit at 435 MHz but a fairly high impedance at the 2 meter
frequency so your receive signal will not be attenuated.

	73,
	Jim AF9A

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