Modifications for the Kenwood TR-2600
Extended frequency TR-2600A
Here is some info on the kenwood model
tr-2600a handie - talkie....
If you want to be able to transmit on
the extended freq area then do the following mod....
The tr-2600a should now be reprogramed
and it should also transmit anywhere it
Remove the front cover of the radio
Locate the ic chip in the lower right hand corner.
Find the 2 diodes number d32 and d33
(they should be the top two on the
right side of the ic chip, also
they have ben cut beforenand (re-soldered)
Un-solder the two diodes (breaking their connection).
Replace the front ctver.
Re-install the battery and turn the
unit on, then push the reset button on the back.
I forgot to add that d32 and d33 on the
recieve board (but that is what is
under the front cover).
Jim - KD0PJ
TR-2600A PLL Unlock Troubleshooting
The owners manual for the TR-2600A lists the lithium battery as a possible
cause of the display showing UL. You may wish to check the battery, but
realistically on a new radio this is probably not the reason for the unlock
If the radio showl UL when first turned on you should perform the
following test. This will help you to isolate the symptom:
There are several other points to check.
With the radio turned OFF, press and hold the 5 key, and then
turn on the radio. Release the 5 key. If the display shows a frequency
indication you may have a pad X2 on the TX unit.
If there is no frequency display other than UL then proceed with
You may also wish to check crystal X1 the Reference oscillator
(10.240 MHz at pin 16 or 17 of IC1.)
Time required for this modification is 1/2 hour or less.
Check trimmer capacitors TC , TC5 and TC6. If you press on the
trimmer and the UL dissappears replace the trimmer.
Check pin number 18 of IC1, it should be 5.4 - 6 vdc.
a. If the voltage is over 6.5vdc replace Q17, Q18, and IC1.
b. If the voltage is less than 5vdc replace Q17 and Q18.
Check the CLK signal at the flex pc board connector, and pin 10
a. The CLK signal should be aprox 4 - 4.4 vdc.
Pin 10 should be aprx. 0 - .2 vdc.
b. If pin 10 is high check Q16, and for cold soldering on the
flexible pc board between the keyboard and the RX unit.
Check the alignment of the PLL section, as given in the Service
Press the RESET pushbutton on the back of the radio.
How to fix TR-2600 keypad
I have a TR-2600, and a few years ago the keypad
failed. The symptom was that buttons in one column of the
pad did not work. I opened the radio up hoping to find a
loose wire that I could re-attach--no such luck.
The "keypad" is a PC board mounted directly behind the
buttons. There are several diodes (and little else) on the
board. I checked the diode closest to the affected buttons,
and it had failed. Once it was replaced with a
garden-variety switching diode, the radio worked fine. So, a
new keypad may not be necessary. I hope this helps.
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