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Re: [Amps] RX protection scheme, is this sound?

To: amps@contesting.com
Subject: Re: [Amps] RX protection scheme, is this sound?
From: Steve <g8gsq72@gmail.com>
Date: Thu, 13 Sep 2018 15:43:30 +0100
List-post: <mailto:amps@contesting.com>
I think I'd go for higher speed diodes. A professional VLF multicoupler I worked on decades ago used a string of 6 or 8 MUR120 diodes back to back. The number was needed because of extremely high signal handling capability, one or two would be plenty for a normal radio.

Another option is to add a sacrificial preamp in front of the receiver(s), using something cheap and readily replaceable. I've learned the hard way, test gear front ends come expensive.

Steve

RX protection sought for either a Kenwood TS-590 or a Red Pitaya
functioning as an SDR for the LF 136kHz band. Change over relay box
for the antenna has a 60 Amp automotive relay grounding the RX line
and changing to switching the antenna to the amp with a Russian high
power co-axial relay 500mS before TX starts. In case of unforeseen
whoopsie an automotive 5W festoon bulb would be in series with RX
antenna input prior to two back to back 6A10 diodes? The festoon bulb
is long enough not to sustain an arc over (I have tested on full power
one side of the bulb to ground). I don't believe the inductance of the
bulb is significant "down there" frequency wise. But I am unsure about
the effect of the big diodes...


Amp is a 1kW + Class D FET amp, is this a sound scheme? The TX has a
separate exciter and the SDR or TS-590 function solely as a receiver
but sharing the TX antenna. Thanks.

--
       Best Regards,
                   Chris Wilson.

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