[Elecraft] 8T & 8R

[Don Wilhelm]

Bob,

Yes, the 8T line is ALMOST opposite 8R - but not quite.  8R goes low prior
to 8T being asserted and 8R can be held low after RF disappears for a period
of time determined by the 8R HOLD menu parameter.

The 8R line is usually the one used for external keying.  There is an
External Amp Keying Circuit schematic (and a partial kit) on the Elecraft
website.  Tom Hammond has an updated version of the circuit that you can
find at www.n0ss.net - this is similar to the amp keying circuit found in
the KPA100.

There is no 8T hold menu parameter - the 8R signal goes low 15 to 20 ms
prior to the onset of RF.

73,
Don W3FPR

> -----Original Message-----
>
> I'm pretty sure I now understand the operation of 8R and 8R HOLD.
>
> Is 8T the inverse of 8R (ie goes high during transmit)?
>
> Is there a 8T HOLD option anywhere?
>
> At the moment I run 100% digital modes and I switch my linear via
> the RTS line on COM1 (which goes high on TX) and an
> opto-isolator. I would like to use the opto-isolator circuit for
> SSB and it looks as though the 8T line might do the trick.
>
>