[TRLog] Need help with Keying/PTT/Paddle interface

[n6tr@teleport.com]

> We have built two interface boxes that have Keying/PTT/Paddle
> interfaces.  I built one a couple of years ago and W4WA built one 
> recently (in other words, they're not using parts from the same Radio 
> Shack blister pack).
> 
> We are using them (well, trying to) with an FT-990, an FT-1000, and 
> an interlock box Ron built that keeps both rigs from transmitting at 
> the same time and enables sharing an antenna/amplifier. 
> 
> Both interfaces work fine with the 990, but not with the 1000 or the 
> interlock.  When trying to key either of these, the PTT will work, 
> but the CW won't send.  If we disconnect the PTT line (physically, 
> not in the program), the CW sends OK.
> 
> Any ideas?  

This sounds like the on voltage of the transistors are too high.
This can happen due to low beta in the transitors.  You can probably
fix the problem by putting the emitter of the CW transistor directly
to ground.  However, now your transmitter will key when you reset
the computer until you start up the program.

This is why I went with relays for everything in my latest swtich
box.  I used a radio shack reed relay for CW and any old relay for
the PTT.  That way you are providing dry contacts to the radio and
you don't care about polarity or voltage drop any more.

Tree

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