[TenTec] Corsair II with separate receiver

[Dr. Gerald N. Johnson]

On Thu, 2008-07-17 at 14:20 -0700, George E. Clark wrote:
> Because in certain conditions my Corsair II doesn't receive as well as my QRP rig, an ICOM 703 Plus, I'm interested in the possibility of operating the Corsair as transmitter and the ICOM as receiver, using a relay such as that described at http://www.ad5x.com/images/Articles/AntennaRelay.pdf .  
> 
> I have a few questions.  You may think of more questions, or have suggestions of other ways to work this problem without much outlay of cash.  
> 
> 1) Which output on the Corsair II do I use to drive the relay, the one for an amplifier?  

It would be great to use the QSK output to run the relay, then a spare
relay contact to enable the Corsair II output, then the relay will be
switching cold. But if you don't need QSK there is a T/R relay output.
Both supply grounds to transmit, QSK by a transistor limited to 100 ma.
> 
> 2) Does that driver meet the specs for the relay described in the link above?

Nope. That relay needs 120 volts AC. Neither of these output are rated
for that. I'd use a P&B KHAU-17D11-12. Its coil takes 87 ma at 14 volts
and it has four sets of contacts. One for antenna, and a set for
receiver muting, and one for transmitter enable.

Maybe a KUP-14D15-12. 3 pole 10 amp contacts. But its coil takes 120 ma
at 14 volts. Might need another transistor to run it. Maybe a 1 amp PNP,
emitter to +12, collector to relay coil, base through 1K resistor to
Corsair II output. 1.5K base to emitter. 1N400x diode cathode to
collector, anode to ground. Other coil terminal to ground.
> 
> 3) This might not be a relevant question for this list, but what on the 703 can I connect to the mute terminal on the switch to mute the receiver when I'm transmitting in SSB?  
> 
A spare contact set on the external TR relay would do well but I have no
idea what the 703 has for muting if any. Might have to use an external
speaker and one of those relay contact sets to open the speaker circuit,
but the 703 receiver will have been overloaded and will probably recover
slowly.

> Thoughts appreciated.
> 
> George, W1XW
> 
73, Jerry, K0CQ