Topband: Detuning Xmit Antenna while RXing.

[Ernie]

Thanks Earl,

I'm not using the mechanical relay in the FT-1000MP to key the 91B Alpha now
and don't plan to start :-)  I run QSK now.  With things as they are now,
I'm able to go directly from the band data jack into the Alpha.  But I know
that RX antenna improvements will require a change in the T/R scheme.

I may have found what I need in a keying circuit designed by K6XX which will
provide the needed isolation. I'll just need to put steering diodes in to
isolate the amp and the Jennings or Kilovac relay(s).

  If you or anyone else has any alternatives, please pass them on...

Thanks & 73,
Ernie KS4Q

----- Original Message ----- 
From: <k6se at juno.com>
To: <ks4q at zingleman.com>; <topband at contesting.com>
Sent: Saturday, July 26, 2003 11:21 PM
Subject: Re: Topband: Detuning Xmit Antenna while RXing.


> Ernie, KS4Q wrote:
>
> "I'm running an FT-1000MP here and am experimenting with various receive
> antennae.
>
> Can anyone point me to a circuit that I can construct to drive a vacuum
> relay to unground my Xmit antennas on Xmit....or ground my Xmit antennas
> on Receive as it may be."
> ==========
> Simple.  Just use the TX GND jack on the MP's rear panel with the rear
> panel LIN switch in the ON position.  It provides ground when
> transmitting and is open when receiving and can be used to
> energize/deenergize the vacuum relay.
>
> If you also key your amplifier using the TX GND jack, make sure you use
> diodes to isolate the amp and vacuum relay coils from each other to avoid
> any relay coil voltage conflicts between the amp's relay and the vacuum
> relay.
>
> You'll need three conductors going out to your vacuun relay: A wire for
> the relay coil voltage, a wire from the TX GND jack and a ground return
> wire.
>
> I don't know how fast your vacuum relay is, but with this configuration I
> would stick to non-QSK operation on CW.
>
> 73, de Earl, K6SE
>
>