Saturday, November 22, 2014

Disabling internal controller on TKR-820

From Mark, N9WYS:

Remove the internal signaling unit. (I'm looking at the TX/RX Unit in the service manual, Page 83, and the Signaling Unit, Page 76.) Unplug both cables from the signaling unit and add the jumpers to the connector.

On CN6 of the repeater TX/RX Unit, or at the cable connector end for CN1 of the Signaling Unit, apply a jumper to pins 2&3, 8&9, 10&11.
Pin 2  = PTT
Pin 3  = KEY
Pin 8  = AFD
Pin 9  = DET
Pin 10 = AC
Pin 11 = GND

That way, if the external crashes, you can plug the internal back in and still be operational.  If the external controller is wired CORRECTLY to the 15 pin accessory plug, it WILL work properly. 
I've used the solid copper 24g telephone wire to short the connections, secured with black tape.  My personal preference was to insert the jumper wires into CN1 connector at the Signaling Unit end of the cable… to reverse the modification, all one needs to do it remove the jumpers and plug the Signaling Unit back in.

NEVER use the internal controller with an external controller. You are
asking for problems.

DVRPTR to TKR-820 cabling

Here's how I've cabled my board to a TKR-820 UHF repeater accessory port:

TKR, purpose, DVRPTR
3, tx mod in, 1 red
4, rx dis out, 4 black
8, PTT, 3 grey
11, grnd, 2 green
13, cos/rus, 6 blue

Also connect pin 1 to pin 11 on the TKR to disable the internal controller. You also should jumper the controller so that you don't create an unintended audio path.

Kenwood TKR-820 DSTAR LSB-208

I found this service bulletin one time, but I haven't been able to find it online since. I'm uploading it here so others will be able to access it. It is a simple mod for TKR-820 repeaters used for DMR or DSTAR. By removing a capacitor on the display unit, the output waveform to the modem is less distorted. I've seen only minor improvement in error rates, but every little thing helps.

To access the capacitor, you remove the top and bottom covers. Then remove the left and right top screws holding the front face in place. Tilt it down, and you have access to the capacitor. You do not need to take the knobs off, or remove the from face from the unit. Total time is less than 15 minutes to complete.

Good luck!