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[CQ-Contest] CW Interface probs w/ TS570S

Subject: [CQ-Contest] CW Interface probs w/ TS570S
From: Alex_van_Eijk_at_DPKO-UNAVEM@un.org (Alex_van_Eijk_at_DPKO-UNAVEM@un.org)
Date: Mon Jul 7 02:03:08 1997
Preparing for next week's IARU contest, I unpacked my Kenwood TS570S 
and the usual gadgets that must connect to the radio. I bought the 
radio recently and haven't been QRV with it yet. Hence my surprise to 
find that my printer port CW interface (the typical 'CT' design) 
didn't work with the radio. It did work just fine last time I used it 
with my TS50. Prepared for emergencies such as this, I replaced the 
NPN (2N3904) transistor with the only spare I've here, suspecting this 
was the problem. (Transistors are not easy to come by in the jungle). 
Again, no joy. The radio does not respond to 'opening/closing of 
contacts' through the LPT port. 

Measuring across the contacts in 'close' status I measured 110 Ohms, 
probably not low enough an R to be considered closed for the 570S. I 
cannot recall what this 'close' value was before, as I never had this 
particular problem with the TS50, or my FT1000. Still I consider 110 
Ohms pretty much for a closed contact. Replacing the original 
transistor, the R was 125 Ohms in close status. Is such an R normal in 
this type of interface, or is the 570S doing something bad to the 
transistor when plugging in the jack on the rear panel?

The 570S documentation does not mention any specific precautions...

Anyone out there with suggestions?

73, Alex D25L

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