Topband: Coupling between bev and other antennas

[Mike Harris]

Hi,

> By the way....NONE of the radio manufacturers actually shut off the
receivers
> when the radio is in transmit mode....by using the added rcvr input with a
> beverage or any other recieve only antenna you run the risk of killing the
> front end of the radio.....

NONE?

My K2 has the 160M and receive antenna switch module.  The receive antenna
connects on the antenna side of the QSK T-R switch and is good to stop 15W.
The TX output from the PA doesn't even see the T-R switch in second antenna
mode, it's isolated by a relay.  The T-R switch can therefore comfortably
block 15W arriving on the second antenna.

So the question is how much separation is required to give at least 18dB
isolation between the TX and RX antenna, assuming 1000W O/P?

The RX front end is certainly not "shut off" but it is protected when used
as a transceiver.

Mike VP8NO (IOTA SA-002)
GQRP 10148
K2 #1400 + KPA100