[600MRG] Receiver protection

[Brian Pease]

Last week I actually measured the voltages induced in my Beverage and 
VPA during 630m TX.  The bi-directional beverage has one end parallel to 
and almost directly underneath my inverted-L TX antenna while the VPA is 
about 400 ft away.  I got 3.6VRMS open circuit on the Beverage and 2.2V 
into 50 Ohms in worst direction.  I got 1.6V OC on the VPA and 900mV 
into 50 Ohms.
I am forced to disconnect the beverage from the transverter input of my 
K3S during TX with a relay, otherwise crosstalk to the transverter 
output distorts the TX sine wave and drives my amplifier nuts!
The K3S has serious protection on the receive antenna inputs.  I would 
email Elecraft and ask what specifically they use.

On 7/10/2018 8:04 AM, N1BUG wrote:
> Does anyone have ideas for receiver front end protection at LF and
> MF? I am worried about my TX signal damaging receivers.
>
> Of course the best idea is to disconnect the RX antenna from the
> receiver while transmitting. Any good solution while leaving it
> connected?
>
> Now I have a pair of back to back 1N4148 diodes across the receiver
> front end but I don't think this offers real protection because they
> allow too high voltage before conducting. Also there is a preamp
> after the didoes which can bring the RF to dangerous levels!
> (Somehow nothing was damaged during last winter operating this way... :)
>
> 73,
> Paul N1BUG
>
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