Modifications for the Yaesu FT-727
Modification for extended coverage
Modification for extended coverage. (This will work for both the
old and new CPU versions)
[From another source:]
Remove the battery pack
locate the RAM backup switch according to your manual ( this will
be the switch FARTHEST away from the battery terminals)
Turn the switch off, count to 4, then turn it back on
Relace the battery pack
Turn the rig on. The readout should be entirely blank. If it
is not, you probably did not wait long enough before turning
the switch back ON, so repeat the above procedure.
Type in the following: ' 001111 '
The rig should now come to life. You will have to reprogram
all the memories as well as the repeater splits for both
bands. The display will now cover 100-199, 400-499MHz, but
bands. The display will now cover 100-199, 400-499MHz, but
it obviously won't work over this range. Mine covers 139-
The reset code is in your manual
The factory code to make the program from the factory is ( 443300 )
and if you enter those
digits the talkie will return to normal again. However if you enter the
code ( 601111 ) you will notice the talkie will come up in a different
mode you can and must input 5 digits instead of 4 to input a freq.
Example in the normal mode to get freq 147.06 you would enter 7060 then
hit the dial button.
In the expanded mode you would enter 47060 to get the 147.06 cause
your display now takes and controls the last 5 digits of a freq
instead of the normal 4.
FT-727R cat- and control-information
This information describes the hardware and software requirements of
the CAT (Computer Aided Tranceiver) System in the FT-727R.
Four connections are used by the CAT SystemL three at the CAT jack,
illustrated below, and one (Signal Ground) at the outer contact of the
MIC or EAR jack.
DO NOT SHORT THE OUTER CONTACT OF THE CAT JACK TO GROUND!!!
[Diagram of the CAT plug:
Looks like a stereo audio jack of the appropriate size.
The outer sleeve is +6 to +12 V DC (Battery Voltage) I do not think this line needs to be connected.
The middle contact is the Serial KeyCode Input.
The center contact is the Serial Meter Output (00h to 0Fh).
See the manual for further description.
All serial data consists of single byte binary codes sent at 4800
baud, TTL levels, with two INVERTED stop bits and one INVERTED start
CAT Control consists of duplication the keystrokes that can be made on
the tranceiver keypad by sending the corresponding keycodes to the
Serial Keycode Input contact of the CAT jack. The most significant
four bits (MSD) correspond with the key column and the least
significant four bits (LSD) correspond with the key row. The Function
key (on the side of the tranceiver) is simulated by setting bit 7.
Results are identical to those described for manual operation in the
FT-727R Operating Manual. Serial Meter Output is sent approximately
every 100 ms while receiving.
[Table for the codes. The lines in  are the original values in the
Yaesu handout, and are followed by the corrected lines as determined
by KB7ABA. Remove the lines in  to see what should be the right table.]
[ @ FUNC F E D C B ]
@ FUNC 8 9 A B C
[ @ NORM 7 6 5 4 3 ]
@ NORM 0 1 2 3 4
E +RPT SIMP -RPT PMS P SET
1 2 3 V c
D SAV-T T-DEC T-SET TX-M S/CH
4 5 6 M MR
B SAVE T-ENC SCAN MC Shift
7 8 9 C <=>
7 LOCK BATT BEEP DUP Step
* 0 # V/U D
email@example.com (Brian Kantor)
I recently acquired a Yaesu FT-727R dual-band walkie, and a few weeks
later sent it in for the $30 processor upgrade that they now come
Performance: not bad. Receiver sensitivity is good (~ .3 uV) in both
ham bands (144-148, 440-450), and power output is 6+ watts on both
bands. Battery life is short (so have two) - you might have to change
batteries once a day if you talk as much as most old farts do - but can
be extended significantly if you use the low-power switch and run at 1
watt. Just monitoring the channel it seems to be fully recharged if
you stick it on the trickle charger while you sleep. There is a
rapid-charge stand for it that supposedly brings a battery up in 1
hour; I don't have one so I don't know much about it.
Yaesu doesn't know how to adjust deviation settings, so you'll have to
do this yourself - mine was set to 4KHz peak voice dev, and 600Hz for
the subaudible tone - which isn't enough for the voice (should be 4.5
to 4.8) and is too much for the tone - should be 300 - 400 Hz for most
radio systems. The tone level from the built-in touch-tone encoder and
keypad is low too, but I've not been able to find an adjustment for
it. I don't have a service manual (if, indeed, there is one) and
absolutely NO adjustment information comes with the radio. You could
probably leave the dev. settings as they come from the factory and not
sound worse than most of the other rice-box radios.
The transmitter looks fairly clean on a spectrum analyzer; the nearest
crud was about 55 dB down but still in the band; stuff farther away was
much lower. They look like synthesizer spikes. You'd expect a walkie
to be dirtier than a mobile or base radio anyway. I wasn't able to
crossmod the front end with the equipment I had, and I've only once
heard crossmod-like crud, and that was standing in the middle of a
large ham-radio swap meet with well over 200+ other walkies being used
near me, so I'd say the front end is pretty good. Again, you'd expect
more performance out of a mobile or base radio than a walkie.
The receiver has lots of audio, but the speaker hobbles it. With an
external speaker, it's quite loud. Internal speaker might not be heard
if you're on a noisy street and you're wearing the thing on your belt
(or stuffed into your back pocket).
The dual-band whip antenna isn't great - a single-band antenna for
either band outperforms it on that band - but none of the three or four
other dual-band whips I tried (some selling for as much as $45) did
enough better that I'd swap it out.
Transmitter audio is quite reasonable - not as muffled as some of the
earlier Yaesu radios were. External microphone uses the standard
method of keying (if the DC resistance of the microphone is less than
about 5Kohm the radio will go into transmit). It also has a Vox, with
two switchable sensitivity levels. The VOX won't work with the
internal microphone; probably it's intended to be used with a headset.
I've modified a Pacific Plantronics aircraft-style clipon headset and
it works well.
Dial illumination is nice. It backlights the LCD panel AND the
translucent keyboard - you can operate it in complete darkness - unlike
other radios that you have to shine a light on the keyboard to see what
It has 10 memories - which store the band, subaudible tone parameters,
and offset as well as the channel frequency. 4 of them can store
separate transmit and receive frequencies for bizarre splits. It needs
more memories. Maybe splitting them so there are 10 for each band,
since there is a band-select button. Or maybe just add more channels.
The battery-saver feature is a receiver-power sampling mechanism - it
turns the receiver on for 1 second each n (n=1-9) seconds until it
hears a signal. I don't use it. Scan is also something I don't use,
so I can't really evaluate it for convenience, but it does work.
Crossband operation is possible - TX and RX need not be on the same
band. Its easy to swap for repeater-reverse too - just hit a button.
Subaudible-tone squelch (for "PL" receive) isn't anything to write home
about. It works, but it requires lots of tone level (500+ Hz dev),
which is probably why they set the transmit tone level so high, and a
small amount of audio leaks through it even when you aren't receiving a
properly-encoded transmission. Its not bad, but in a quiet room you'll
Ruggedness - well, it's plastic. The window over the LCD scratches
quite easily; if you keep it in the vinyl slipcover you won't have this
problem, but you have to take it out to change the battery and the
buttons on the keyboard are harder to press in the slipcover. The back
is die-cast aluminum and is the heatsink for the power amplifiers; the
belt clip is attached here and seems quite sturdy. Its a good place to
engrave your name, callsign, and driver's license number. The rest of
the housing is polystyrene, and shows nicks and dings quite easily.
You can also melt it with a soldering iron, which makes hot-stamping
your name, etc. into it quite easy. I'm probably going to cut some
appropriate-sized notches into a Motorola or RCA holster and use that
to hold the radio on my belt, since that will give me 1/8" or more of
hard leather to protect the radio.
The battery slides into a track on the bottom of the radio and is held
by a plastic latch. Its quick to change. The track is large and heavy
enough to survive most drops, but it's held on by two small screws into
thin metal brackets that will undoubtably strip out after a couple of
falls. At that point, you can ream out the threads and solder a couple
of nuts to the back of the brackets, and use some #4 stainless screws
to hold the slide in. I haven't had to do that yet; I'm just planning
for the future. The latch is also plastic; it will probably shear off
if you drop the radio on its side from any great height.
Most of the circuitry is surface-mount components on circuit boards in
modules; they look unrepairable by most people without hot-gas
soldering equipment. They also look expensive and somewhat fragile
since they're not shock mounted or damped. I don't think this radio
will survive falling out of my back pocket 60 feet up on a tower like
my old Motorola HT-200 did. I don't think I'll pound nails with it
either, like the Motorola salesman was doing with the HT-200.
Out-of-band performance is nice. On highband, it works from about
142-154.5 MHz, with power and receiver sensitivity falling off a bit at
the upper extreme. It would probably work at higher frequencies if I
tweaked the PLL/VCO a bit, but I haven't done that yet. Ask your
dealer for the MARS instructions and you'll get two pages of
crudely-copied instructions on how to tweak the PLL/VCO. On UHF, it
works from 416 to 463 MHz, but really has only marginal sensitivity and
low power output outside the range 435 to 455 MHz. It doesn't get
dirty out of band either, just doesn't perform as well. On our local
DEA repeater frequency (418.x MHz), it's about 10 uV sensitivity, and
wouldn't hear them at all if I didn't live about 1.5 miles from the
I think it's a good buy for $400. Its got some nice features and works
well - better than the alternative of buying TWO other walkies, one for
This counter shows the number of hits since the
9th February 2000
Go Back To The Yaesu Mods Page
Go Back To The Main Modifications Page
Go Back To The CB / HAM Radio Main Page
Go Back To The Main Home Page
Copyright © The Defpom 1997-2008