[600MRG] [rsgb_lf_group] Receiver protection

[Bill Cromwell]

Hi David,

I wondered if somebody was going to mention shorting the RX input to 
ground. I supposed that was too simple and old-fashioned for today's 
hams so I sat on it. That's what I do and always did. I have the grey 
beard to prove it :) Just because it's old school doesn't mean it won't 
work any more.

73,

Bill  KU8H

On 07/10/2018 12:13 PM, David G0MRF via 600MRG wrote:
> Hi Paul
>
> I'm sure you will get many good ideas from the group.
> I took the view that my preamp protected the receiver....and the preamp
> was expendable. - Also the max output from the preamp was not sufficient
> to damage the receiver.
>
> Even so....After using it for a while, I decided that a little more
> protection was called for, so I placed a small relay (about 1/2 inch
> square) to short the input to the preamp to ground when the system was
> in 'transmit'
>
>
> 73
>
> David
>
>
> -----Original Message-----
> From: N1BUG paul at n1bug.com [rsgb_lf_group] <rsgb_lf_group at yahoogroups.co.uk>
> To: rsgb_lf_group <rsgb_lf_group at blacksheep.org>; rsgb_lf_group
> <rsgb_lf_group at yahoogroups.co.uk>; Discussion of the Lowfer (US,
> European, & UK) and MedFer bands <lowfer at mailman.qth.net>; 600MRG
> <600MRG at mailman.qth.net>
> Sent: Tue, 10 Jul 2018 12:05
> Subject: [rsgb_lf_group] Receiver protection
>
>
> 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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bark less - wag more