SB-201 & TS-440S

[Scott W4PJ]

My bet is that the amplifier has a 120V relay coil.
That might cook the T/R switch in the rig. - Rated for low V

An intermediary relay used between the rig and amplifier is easy
to construct.

1 - Radio Shack DPDT relay with 12VDC coil and 120V contacts,(you only need
    1 pole but I haven't seen any SPST relays at R-S)
3 - rca jacks
1 - small toggle switch SPST
1 - diode (1N4001 or similar)
1 - small plastic R-S box to put it all in

(rca jacks) for:
1. 12VDC source
2. T/R switch in rig
3. from intermediary relay contacts to Amplifier

Toggle switch (on/off) for 12VDC source

Diode (1N4001 or similar)

If the rig has a 12VDC source (switched with the rig powerup) use that.
If not, any 12VDC source can be used.

Basically, the 12VDC source powers the intermediary relay coil.[Jack#1]
the toggle switch for 12VDC on/off and the rigs T/R switch completes the
circuit [Jack#2]. When the intermediary relay coil is energized the
contacts complete the Amplifier relay coil circiut [Jack#3] and the 120V
doesn't have to go through your rigs T/R switch.

Place the diode across the intermediary relay coil 12VDC connections,
cathode to + side to protect rigs T/R switch from voltage spike when
you unkey and the coil de-energizes.

I hope this helps. Really simple way to protect your rig.
de (Scott) W4PJ

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