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RE: Converter Protection




> In a message dated 12/5/2000 8:45:50 AM Eastern Standard Time,
> tmwebb@ionet.net writes:
> 
	>Having fried a Drake 2.4GHz converter a few months ago, I decided
to 
	>install a Ramsey RFS-1 rf sensing switch to protect any future
S-mode 
	>converters.
	>As a matter of scholarly inquiry, any better ideas floating around
out
	>there as to protecting mast-mount converters from inadvertent rf?


Yet another way of doing this, if you have an FT-736R:

Locate the "CNTL UNIT" on the FT-736 connection diagram.   Cables from
connectors J05 thru J08 on this board go to RF UNITs for each band.  Pin 6
of these connectors is labelled "TX."  If this TX line is "open," the radio
will not transmit on that particular band.

I use a small reed relay to "open" this line, with the relay coil wires
brought out one of the back panel holes.  This isolates the circuitry inside
the radio from any of the control circuitry you might add to perform this
switching function.  BTW, the relays are available for free (you pay the
postage).  See our club's web site  www.w9rca.com.  Click on "homebrew."
Near the bottom of the page,  Wabash 9091-05-01.

In my shack, I have a panel with bulkhead coax connectors where I have
brought out the antenna cables from the back of the FT-736.  Next to each
coax connector I have mounted a quarter inch phone jack.  Putting a plug
into the jack grounds one side of the reed relay coil and closes the relay
allowing the radio to transmit on that particular band.  Coax from real
antennas have a phone plug tied near the end of the coax so you can plug it
in when you connect the coax.  Cables to preamps and receive converters have
no phone plugs attached to the cables.  It's been 100% effective.


73,
Jim AF9A

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