Topband: Interface cable

Tom Rauch w8ji at
Mon Jul 28 22:50:49 EDT 2003

> Thanks to all who replied to the question about the interface cable so I
> can drive my SB-1000 with the "706".

Having designed the SB1000 and owning two 706's, I'd never connect the 706
to the SB1000 without an interface buffer of some type. The IC706 has the
most sensitive to damage keying system of any radio on the market. It
absolutely has to have a buffer circuit that is designed to work with

> I was told I have to modify the amps ALC circuit.

There is no reason to use ALC, and no reason to modify the ALC because it is
not useful anyway with that radio. The ALC in the 706 is slow responding and
has severe overshoot, so don't worry about it. Just buffer they keying line.

I designed a keying interface for Ameritron that uses an op-amp input that
works with any production series of the IC706. I'd use something like that,
or copy something like that. I use a simple PNP transistor with my plain
706, but that simple circuit locks up my 706MKII. It requires an op-amp.

73 Tom

More information about the Topband mailing list