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Author Topic: KW TS-940S Used With Data and SSB  (Read 248 times)
K4CFQ
Member

Posts: 18




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« on: July 17, 2009, 05:54:41 PM »

A question for any TS-940S users who are using the rig for data and SSB.  When using for data (e.g., PSK31) and the Acc2 jack is plugged in, the microphone is inoperable.  Thus to use for SSB Acc2 has to be unplugged.  This is rather inconvenient.  Does anyone have a solution they use that works a bit easier and doesn't require the plug/unplug of Acc2?
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KL0S
Member

Posts: 132




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« Reply #1 on: July 18, 2009, 07:47:36 PM »

That's an old documented problem with a very easy fix...

Install a small switching diode (1N914 works fine) between pins 9 and 13 of the ACC 2 jack with the cathode to pin 9.  Once you've done that PTT closures made via the rig's SEND and mic PTT switches will put the radio into transmit WITHOUT muting the mic.  On the other hand when your digital interface grounds pin 13 at ACC 2 to switch to transmit it also grounds pin 9 to mute the mic.

I installed the diode inside the DIN plug that comes from my MicroHam Digi Keyer....it's a little tight but can be done if you're careful.

Dino KL0S
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K4CFQ
Member

Posts: 18




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« Reply #2 on: July 25, 2009, 07:52:26 PM »

I use the Buxcomm digital interface for the Kenwood TS-940s.  As it comes from Buxcomm, there is a switching diode from pin 9 to pin 13 installed in the ACC2 plug as you mentioned.  However .... It was installed backwards.  The cathode was soldered to pin 13... and the schematic that came with the interface shows it that way also.  I removed the diode, and installed a new 1N914 (cathode to pin 9) and everything now works AOK. Thanks for alerting me to check that ... I wasn't aware of that old Kenwood issue.  Note:  When using PSK 31, I am now getting some sudden spikes every 5-10 seconds in the audio signal causing the ALC to kick up and this also affects the IMD.  Never had this before... so don't know what is causing it.  I had some work done on the radio, but I have not noticed any problems on SSB.  Always some problem to chase down.
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K4CFQ
Member

Posts: 18




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« Reply #3 on: July 25, 2009, 08:59:11 PM »

With this change however, I find that I have to unplug the mic in order to use the digital modes.  Otherwise, the mic is affecting the digital input the the TS-940S
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