I think I can help
Lets see if I can walk you thru this one Cap.
I assume that you are trying to join a VHF and UHF TK series radio together into one control head using the KRK-4DB. First, you have to pick your primary radio. This is the first radio connected to the control head. In my case it was the TK-630H low band. You must connect it to the control head via the port that states "To control head". Next you have to modify the second radio. In my case it was the TK-830(G). Remove the four screws that fasten the top cover of the radio. This is the shorter of the two half covers. Inside you will find the firmware chip (I believe they MUST match, however, I am not certain. If they are not compatible, they will not see each other.) Mine are FAB/FAB. Now look for W102. It is located to the right of the three grouped white connectors in the middle of the board. This resistor wire must be cut, but leave in a position that they can soldered back together if you wish to someday reverse the process. Now, find solder points A and C. They are clearly marked and are quite easy to locate. A is toward the front of the board near the rainbow connector. C is right next to the W102 resistor that you cut. You must now solder a jumper wire between solder points A and C. Reassemble the radio and connect radio 2 to radio 1 via the KRK-4DB and apply power to both radios. You should hear the relays click in both radios indicating that they are both operating.
Notes:
1. The total number of channels will be shared over both radios. You may make it in any combination you wish, but cannot exceed the total number of channels per one radio.
2. Both radios must be capable of the same number of channels. If not, I recommend purchasing the "Kenwood TK-630/TK-730/TK-830 KCH-5 160ch Upgrade Kit" via eBay Item #350397363026.
This will work for the Basic KCH-3 as well, and will upgrade it to a 99ch. You will need 2 of these kits in order to upgrade your dual band kenwood (you will receive 4 chips, but require only 3). They come with detailed install instructions (WITH PICTURES, unlike mine).
3. You can connect the speaker to 2 different places (this will conduct audio traffic from both radios).
A- to the remote head via the 6 pin connector with pins 9&12 jumped on the 15 pin accessory plug on the back of radio 1.
B. to pins 6 & 12 of the 15 pin accessory connector on the back of radio 1.
4. The pin config on the accessory connector was not numbered in the order I expected, see below
3 6 9 12 15
2 5 8 11 14
1 4 7 10 13
Good luck and reply with any questions you may have. I hope you have a steady hand with a small soldering iron. Be extra cautious. I wouldn't want to see a good radio go to waste (LOL). If all works well I garuntee you will love this rock solid setup. I know I do.
