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:]
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.


[Diagram of the CAT plug:
See the manual for further description.

Data Format:

All serial data consists of single byte binary codes sent at 4800 baud, TTL levels, with two INVERTED stop bits and one INVERTED start bit.

Key Codes:

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


     1    2     3    V     c

     4    5     6    M    MR

     7    8     9    C    <=>

     *    0     #   V/U    D

Ft-727 review (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 equipped with.

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 you're doing.

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 hear it.

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 repeater.

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 each band.

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