Modifications for the Yaesu FT-51

Modifications for the Yaesu FT-51
Extended RX and TX frequency

Disclaimer: Perform this procedure at your own risk. The poster(s) of this procedure assume no liability, and this procedure is posted for general information only. The FT-51R radio is not fcc-type accepted for transmission outside of the amateur radio frequencies. This modification enables transmission on frequencies outside of the amateur radio band, and is legal for those individuals with mars/caps certificates. This modification requires the use of a low power fine tip soldering iron. individuals who are not experienced with soldering of surface mount technology should not attempt this modification, you could ruin your radio.

Remove the battery pack from the radio.
Remove the four screws directly beneath the battery pack on the radio.
Remove the two screws holding the contact portion of the battery compartment
Remove the screw and battery pack release lever.

(the following steps make removal of the battery holding compartment easier)
Remove the four screws on the bottom portion of the back of the cabinet. Carefully remove the two halves of the radio. Pay attention to the gasket as you are seperating the cabinet.
Remove the battery pack holding compartment.

The section you will know be working with is directly underneath the battery pack holding compartment (behind the touch tone pad).
There is a ribbon cable connected to the control board. You can leave the ribbon cable attached if you're a GOOD solderer, or you can release the two little black levers on each side of the ribbon cable and CAREFULLY slide the ribbon cable out of the socket and hold it back towards the case with a piece of tape. Be careful not to put a bend in the ribbon cable or pierce it.
Locate a set of etched jumpers on the pc board. They are located adjacent to the bend in the ribbon cable. They are not marked, and are situated as follows (o-o indicates closed, o o indicates open):
```
      JP1001   o-o
                     o o JP1005
      JP1002   o o
                     o o JP1006
      JP1003   o o
                     o-o JP1007
      JP1004   o-o
```
Using solder wick or your preferred method of solder-removal, carefully remove the jumper for JP1007. This enables the 134-174, 420-470 MHz transmit.
Reassemble the radio, remembering to reinstall the gasket, and to carefully reinsert the ribbon cable if you removed it from the socket, and fasten down the little black socket locks.
Press the MHZ / and MHZ / buttons simultaneously while turning the power on to the radio. This enables the modification.

Some notes:
I experimented with removing JP1004, and it had no apparent effect. I did not experiment with any of the other jumpers except JP1007. There still may be 800 MHz receive buried some where in the radio, the Japanese version has 800 MHz receive. An earlier posting of mine indicates four large resistors (well, non-surface mount) connected between various microprocessor and memory pins, clearly an add-on. Experimentation with removing these produced no effect, HOWEVER, this was prior to my discovery of the JP1007 mod. I've played with the radio enough now, and don't want to push my luck, so let's let someone else try to find out if there are any more secrets buried in this fine piece of gear.
Adjusted the threshold of the Squelch

The FT-51R allows several operating parameters to be adjusted through the keypad. I have found that the high and low modulation levels and the squelch threshold can be adjusted this way. The procedure to accomplish this is as follows;

Turn the radio off

Hold the volume up, volume down, and CALL buttons down, while turning the radio on. ( This requires you to carefully place your fingers on the buttons. I had to try a few times, but quickly found the proper finger positions. )

The menu should now read BAND1

Rotate the Rotary Selector Dial to the option you want to adjust. ( There are a number of options to choose from. I have only tried the MOD H and MOD L options. I do NOT recommend adjusting other options without proper test equipment.)

Hold the FM function button for 1/2 sec. This enables you to change the displayed values.

Use the MHZ UP/DOWN buttons to select a new value.

Press the FM function button to save the new value.

Press the BAND button, and repeat the above procedure to adjust the parameters for the other band. (Note: To switch to the other band, both bands had to be "ON" when the radio was previously turned off.)

Press the CALL button to exit the adjustment mode.

YAESU FT-51R

Expanded Transmit 140-174 MHz, 420-470 MHz
MARS & CAP MODIFICATION

Remove Antenna and Battery.

Remove (6) black screws in rear plastic cover plate (where the battery would normally fit).

Remove the (1) small black screw in the battery slide switch.

Loosen (but don't remove) the (4) black screws on the upper back of rear case and slightly separate the rear radio case.

Remove the "L" type plastic cover CAUTION: Watch out for the delicate ribbon cable.

Locate and unsolder jumper pad #6 (see Figure 2 below for jumper locations) (Pads 1,7 should now be jumpered) (Stock, Pads 1,6,7 only).

Reinstall the "L" type plastic cover.

Tighten the (4) case screws on rear case.

Re-install the (6) black screws in rear plastic cover plate.

Re-install the (1) small black screw with the battery slide switch.

Now attach the antenna and battery.

Turn off Radio... Press and hold both UP & Down Arrows Keys (right side) while turning on the Radio.

Modification now complete!

Jumper locations.

For European tone burst, add solder to jumper 4.

| | 1 o | | o 2 | | 3 o | CPU | o 4 | | 5 o | | o 6 | ________| 7 o | |

This counter shows the number of hits since the 24th December 2000

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