You need to do mono-to-stereo properly. Most key jacks on modern radios are 
ring-tip-sleev, so you need to make sure that your keyer only shorts the tip 
when keying is down, and that it does not short the ring to the sleeve. Hope 
that makes sense. These rigs, both on the front and back panels, are 
assuming that a paddle is being connected, rather than a straight key or 
bug.



Lloyd Rasmussen, Kensington, MD
http://lras.home.sprynet.com
-----Original Message----- 
From: Mike Keithley
Sent: Friday, February 19, 2016 11:51 PM
To: [log in to unmask]
Subject: need help connecting MFJ-452 keyer to my TS590SG

Hello list,

I need help connecting my MFJ-452 keyer to my Kenwood TS590SG. This keyer is 
a keyboard-based system where you type on the keyboard to generate CW.

My problem is that when I connect the keyer to the straight key jack on the 
back panel of the 590, the system behaves as if the key is frozen down and 
the sidetone is always on. It's as if the keyer's output is shorted.

I checked the resistance at the keyer's output. It is over a meg-ohm when 
not sending code (key-up I suppose) and zero ohms when sending code (key 
down). I set my ohmmeter to continuity mode and hear code generated in the 
meter's speaker. I also checked the voltage across the keyer's output. The 
voltage was around plus 50 milivolts when the key was up and plus 0.75 volts 
when the key was down. However, I did these measurements with the Kenwood 
disconnected from the keyer. I believe the straight key is connected 
properly by noting that when I disconnect the cable from the keyer output, 
the side tone turns off.

Again, the problem is that the Kenwood is behaving like the key is always 
down.

Thank you for any help.