[Elecraft] K2 and Kenwood TL-120 lonear

[Bob Towers]

> 
> I don't actually own one Bob but I have taken a look at the cct.  I 
> would think that the MK line is probably (Manual Keying) by applying an 
> earth at this point.  RL is keying the relay via a transistor switch, 
> probably for those radios that have a solid state keying line that can't 
> handle the relay current directly.  I have enclosed a copy of the TS130V 
> manual below which covers linear connecting.  It could have done with a 
> diagram for clarity, but the text indicates that pin 4 of the radio goes 
> to ground on TX.  This fits with the MK line on pin 4 of the linear.
> 
> Hope this helps,
> Trev
> 
Yes it does!

I've blown up the appropriate part of the TL-120 circuit diagram... The RL line goes to the base of Q10, which is the switching transistor. It's possible that connecting MK to RL will cause Q10 to conduct and effectively earth RL-1 and switch it on. I think for safety's sake, I'll put a resistor between MK and RL: I don't want to blow Q10. Eathing MK (pin 4) will switch RL-1 on, too

I'll have a trial run - MK to earth - and then see if I can do something with RL via COM1/CTS/RTS + optoisolator, which would be a much more elegant solution.

73

Bob
2M0KDZ