[NLRS] Question on FT897 TxH for EME use

[David Palm]

I haven't done it myself, but according to W1GHZ what you're describing
using that specific input to hold off RF is the safest possible way to
protect the preamp.  Everything else is a step down in security, according
to Paul.

On Thu, Dec 17, 2020 at 11:07 AM Jon Platt via NLRS <nlrs at mailman.qth.net>
wrote:

> Over the last several months I've been piecing together a (very) small
> 1296 EME station.  I thought I would use essentially what I have to see if
> I could first actually hear anyone off the moon.  Last Fall I was
> successful in seeing (and hearing a little bit) the ON0EME 1296 EME beacon
> as well as decode a few stations.  My conclusion was that I can hear some
> of the big guns.  So now I am working to add transmit capability.  Towards
> that end, I now have every thing I need (I think) and have been working on
> designing the sequencing.  I plan on using my Yaesu FT897 with an older 50w
> DEMI 1296 transverter.  I do have a 402 series DowKey latching relay for
> T/R that has 80 dB of isolation and can handle 250 watts at this
> frequency.  This relay also has the "optional indicators" pins that can
> provide a signal that the relay has actually switched.   I have a W6PQL
> latching relay driver and his sequencer board.  My thought is tie my FT897
> TxH (transmit inhibit) pin to +12v and to use the 402 relays indicator pin
> to pull TxH low (when the relay actually switches).  In theory, the FT897
> will not produce RF output if TxH is held high, thus in this design my
> FT897 will not transmit until the T/R relay is actually switched to
> transmit and thus protect my preamp.  I do plan to also use appropriate
> sequencing, however using the FT897 TxH in such a way seems like good
> insurance.  My question for the group is does this make sense and has
> anyone used their FT817/FT857/FT897 TxH capability in such a way?
> 73, JonW0ZQ
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