[Elecraft] Delay between key in, key out on XV

[Evert Bakker (PA2KW)]

Hi John,

I've been struggling around as well to realize a safe and reliable setup for
the combination K2 / Transverter / Power-Amp / Pre-Amp / Coaxial relay, from
which the last three components in a separate box mounted in top of the
antenna tower.

It is no way safe to use the 8R or 8T voltage as a command line without
positive feedback from your relay as to acknowledge that it has changed
state. So I decided not to make use of that "option".

I designed and built myself an interface box to which the microphone and
paddle-key are connected. By activating the PTT (mic) or the paddle, I first
generate a TX-request which is led to the sequencer. The sequencer takes
care for proper timing and switching of the coaxial relay, preamp and power
amplifier. If all has been switched over, the sequencer gives a
TX-acknowledge which is fed back to the K2 interface and together with the
request puts the PTT or paddle-key through to the K2.

I use the K2 interface as well for proper isolation of audio signals between
auxiliary peripherals like PC / audio-keyer / etc.

There is a "quick & dirty" way of preventing RF injection from the K2 into
your XV system. Use the (drof of) 8R voltage as an input for your sequencer.
Make the timing and switching happen, and use the feedback (TX-acknowledge)
to switch a small coaxial relay which is connected to the RF-out connector
of the K60XV. 

                Coax-Rel

                    /--- NC --> 50 Ohm 1W
K2 K60XV RF-out ---/  
                     --- NO --> to IF-in XV 

Just an additional hint:
Make sure that you use the coaxial relay at the antenna side in such a way
that it is in the TX mode when NO voltage is applied. If your cable brakes,
or the power supply fails, the power amp will always see the antenna. If you
use the relay this way, a failure is easily detected as your receiver is
"dead".

73's and Good luck

Evert PA2KW




________________________________________________________________________

I've been searching around and I can't seem to locate any information
on whether and how much delay there is between key in (or 8R) and key
out on the XV series transverters. I need an early PTT for my
about-to-be-integrated outboard T/R relays .. I've got a external
sequencer solution, but I got to thinking that if there's at least 50
or 100 ms delay coming out of that I could get rid of the diode on the
key in connector and use the 8R to fire a driver for the T/R relay.
Anyone know?

de w1rt/john