[Heathkit] Amp Keying Interface?

[Peter Markavage]

If we're talking about the original equipment (the initial post), a
FT-847 driving a SB-200, your statement is correct since the SB-200 has a
DPDT antenna relay already installed in it. If the 847 (or any
solid-state transceiver) is hooked to the SB-200, and the amplifier is
not powered on, the 847's RF goes into the SB-200 and through the relay
contacts and back out through the SB-200 antenna connection. However if
the SB-200 is powered on, voltage is hanging on one side of the antenna
relay coil, so when you key it with the solid-state transceiver through
the soft-key interface, the interface pulls the cold side of the antenna
relay down to zero causing it to actuate. Now transceiver is connected to
the input of the amplifier and amplifier output is connected to antenna. 

A "number" of us have replaced the sensitivity control for the SWR
adjustment on the SB-200 front panel with a similar resistance pot but
one with a push-off/pull-on switch. The switch is wired in series with
the relay coil. This way, if you're working someone with the amplifier in
operation and decide you don't need the amplifier for this contact, you
just push the switch in disabling the antenna relay action. The
transceiver then just feeds one set of relay contacts on the antenna
relay and goes out to the antenna with the second set of contacts. The
amplifier remains in a standby condition, and to resume amplifier
operation, you only need to pull the switch to the ON position.

Pete, wa2cwa

On Tue, 31 Jul 2007 19:10:48 -0500 "Rick Brashear" <rickbras at airmail.net>
writes:
> When the amplifier is not keyed it's a straight though connection, so 
> it
> would automatically go back to the receiver.  Am I thinking 
> incorrectly?
> 
> Rick/K5IAR