Hi All, Happy New Year! We are all older and therefore should be bolder
Is anybody using a IC-290A as a transverter IF? If so, how are you doing the PTT switching? My DEM 23CM transverter requires the grounding of a relay to switch to transmit and there is no convenient way of doing that from the accessory socket on the IC-290A (that I can figure out anyway).
I have thought of using a RF-sensing relay but cannot find a suitable circuit. Anyone got one?
73
Wayne VK4WDM
Hi Wayne,
Have you measured the PTT line on the ACC socket? According to the circuit, pin 2 on the ACC is exactly what you need. It is pulled high (13.8V) by a 4k7 resistor (R6) and grounded either by the MIC PTT or the Tone button. You could even pull it to ground to switch to TX if you wanted.
I don't know what the DEMI PTT line looks like so you might have to use a PNP transistor to power a low coil current relay. The relay contacts would key your transverter giving you full isolation.
Here's the first link I found on Google -
http://www.electronics-tutorials.ws/blog...rcuit.html
FWIW, I think RF sense switching is a little agricultural for SSB operation. Try as you might there will be times when that PTT chatters. Much better to be in complete control with relay switching.
Update.
If you have the old DEMI 1296-144 transverter you can do away with the extra transistor and just take pin 2 of your ACC socket direct to the PTT input of the transverter. I imagine all their transverters will have a similar design.
(15-01-2018, 09:20 AM)VK4WDM Wrote: [ -> ]Hi All, Happy New Year! We are all older and therefore should be bolder
Is anybody using a IC-290A as a transverter IF? If so, how are you doing the PTT switching? My DEM 23CM transverter requires the grounding of a relay to switch to transmit and there is no convenient way of doing that from the accessory socket on the IC-290A (that I can figure out anyway).
I have thought of using a RF-sensing relay but cannot find a suitable circuit. Anyone got one?
73
Wayne VK4WDM
Hi Lou
You will pleased to know that my glasses have been upgraded and new firm-ware has been loaded into my aged brain. I now have the PTT sorted.
Wayne VK4WDM