Modifications for the
Here is some info on the Kenwood
model tr-2600a handy - 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 reprogrammed
and it should also transmit anywhere it will receive...
- Remove the front cover of the
- 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 beforehand
- 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
I forgot to add that d32 and d33 on the receive board (but
that is what is under the front cover).
Jim - KD0PJ
PLL Unlock Troubleshooting
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 condition.
If the radio show UL when first
turned on you should perform the following test. This will
help you to isolate the symptom:
- 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 step II.
- You may also wish to check
crystal X1 the Reference oscillator (10.240 MHz at pin
16 or 17 of IC1.)
There are several other points to
- 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.
- If the voltage is over
6.5vdc replace Q17, Q18, and IC1.
- If the voltage is less
than 5vdc replace Q17 and Q18.
- Check the CLK signal at the
flex pc board connector, and pin 10 of IC1.
- The CLK signal should be
aprox 4 - 4.4 vdc.
Pin 10 should be aprx. 0 - .2 vdc.
- 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 manual.
- Press the RESET pushbutton on
the back of the radio.
Time required for this
modification is 1/2 hour or less.
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
|Some cases of
PLL on the TR-2600A may be caused a failure of the crystal
oscillator circuit X2, X3, and Q13. This may be corrected
by performing the following changes.
On the TX unit (X56-1470-10)
Replace Diodes D13, and D14
(MA856) with a series pair of BA282's as shown in the
diagram below. Also change resistor R54 to 47 ohm as
BA-282 diode, 4 each.
47 ohm chip resistor (RD73FB2A470J), 1 each.
This change is applicable to
serial numbers before SN 702xxxx.
Time required for this modification is 1 hour or less.
Remember it is Illegal to transmit out of band. This Modification is for
Informational purposes ONLY.
Doing such modifications on your radio may void any warranty and damage your equipment.
All mods found on this database are offered to me by other amateur radio hams or captured by Packet system.
KB2LJJ take no responsibility or liability for any damage done resulting from any modification.