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I was able to obtain a couple of these
radios for a fair price, and I must say they are quite easy to modify / program
for use on 70cm UHF Ham frequencies. I noticed the lack of instructions on the
web for doing this, so I decided to remedy this situation, and pass on what I
know about the radio. Let's start with some specifications.
Frequency range: UHF
400MHz to 510MHz although the highest power output on mine (into a dummy
load of course!) was from 430 - 480 MHz (I'm told this will vary from
radio to radio, depending on what service it was tuned to) generally the radio
should be O.K. for 70cm (420-450MHz) unless a radio shop did some HEAVY tuning
to it. Yes the radio will tune to frequencies well above and below these limits,
however, it just won't transmit there, it could be possible that the same tuning
circuitry is used across a broad line of Kenwood's business radios, and only the
final stages are different between models.
Figure
1 In this photo you'll see the radio with the cover just pulled
off, everything is still in place, and the switch can be seen clearly in the
right rear corner.
Figure
2 In this photo the speaker is removed, showing the speaker
holder that must be removed for access to jumper CN7, or to facilitate soldering
wires for the external programming switch.
Figure
3 This photo shows the detail of CN7, and also the switch mod
can be seen.
Figure
4 Photo showing the radio display in programming mode.
Jumper detail for CN7:
CN7 o--o o
Program enable
CN7 o o--o Program disable
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Specifications:
Channels:
16 channels, each of which can be programmed with its own Split or Simplex
freqs. and TX and RX PL.
Power Output:
25 Watts, again this will vary depending upon where the "center
frequency" of the radio is tuned to. Both of my units transmit 33 Watts
at their center frequency into a 50ohm dummy load. From 430-450 MHz I get 25
Watts, and at 420 MHz I get 20 Watts, that's good enough for me as I'll be
using it for repeater and simplex work between 440-450MHz.
CTCSS / PL:
Supports all the standard CTCSS/PL tones for TX and RX.
Programmability:
Radio can be fully programmed from the front panel.
Programming:
With that out of the way, let's begin.
Open up the radio top cover (FIGs. 1&2) and move CN7 over, this is the
jumper closest to the front of the radio and to the right, (see FIG.3 below)
and turn on the radio. The display will now show you RX frequency instead of
channel (FIG. 4), to tune fast (MHz), press the button that looks like this
-/\/- while turning the tuning knob, release to tune (KHz). To switch to RX PL
press the PTT on the Mic. once, then set the RX PL and press PTT once, then
set the TX freq. press PTT once and set TX PL then press PTT once, this will
start over at RX freq. only on CH 02, you can keep repeating this all the way
to CH 16, if you press PTT on an empty channel it skips to the next channel.
For simplex, TX is the same as RX and you can leave PL OFF on both if you
wish, as the radio has an automatic squelch. To save your changes when
complete, just keep clicking the PTT (skip through any un-used channels) until
the display shows END, then just switch off the radio, move the jumper back,
and close 'er up! DON'T TRANSMIT OUTSIDE THE HAM BANDS..... YOU'VE BEEN
WARNED!
Modification:
For those who really want to do a
great mod, you can add my little improvement.... an external switch for CN7 to
allow "no tool" programming. When looking at the TOP of the radio,
look at the rear cooling fins on the antenna side, leave the outside fin
intact and hack out the second fin with a dremel tool, leave the little
reinforcement tab at the very rear for obvious reasons. You'll now notice a
nice place to mount a small SPDT toggle switch from inside the radio between
the outside (first) fin and the third one (See FIG. 3), be careful when
drilling that area to prevent metal fragments from entering the radio. Mount
the switch, solder three wires to the jumper pins of (CN7), use small
heatshrink tubing to prevent shorts, and close up the radio. You can now
re-program anywhere with NO TOOLS! You are doing these mods at your own risk
of damage to your radio. Don't perform ANY part of this modification unless
you are comfortable or experienced in doing so. DON'T EVER TRANSMIT OUTSIDE
THE HAM BANDS..... YOU'VE BEEN WARNED! I've performed this on both of my
TK-805 radios and it works great.
Don't like the microphone you got
with the radio? Maybe you didn't get a mic. with it at all! Well don't worry I've
even taken care of that detail.... here is the mic. pinout, isn't this great!
If you're going to use your own mic.
you'll need a 6 pin modular plug (RJ25) these are Radio Shack P/N: 279-421
When looking at the front of the radio
from left to right the modular socket pins are as follows:
1.
2. 3.
4. 5.
6.
HOOK / MIC / MIC GND / PTT /
PTT GND / NC
NOTE:
The 6th pin is not used, possibly a cloning or programming interface option.
Pin 1 is connected directly to the mic.
hook on the rear of the stock mic. this is used on scanning radios.
When the mic. is lifted off the hook, ground is lost to pin 1 (hook) causing
the radio to stop scanning channels
returning it to the "home" channel. |
