Hello Steve and Chris Hayes, thanks for the replies. I have gone for
two ultra fast high power diodes in back to back with a festoon bulb
of 5W at 12V in series before them. It was not practical to work pre
the amp due to how it's driven. It RX'd and TX'd at half power all
last night and the Red Pitaya LF receiver is still alive and well this
morning, so so far, so good! Thanks again.
On Thursday, September 13, 2018, you wrote:
> 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.
--
Best regards,
Chris mailto:chris@chriswilson.tv
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