Modifications for the Yaesu FT-5100

I discovered by accidental application of fat finger: if the high/low button is held while turning on power, that transmitter time-out may be set. If you do this, the left VFO display will show some number between 00 and 60. The factory default appears to be 15. The number can be changed by rotating the frequency knob.

I tried an experiment, setting the number to 01. I keyed up into a dummy load. After one minute, the transmitter shut off with, "Err" displayed in the VFO.

I'll leave it up to you to decide a use for this feature. If you're an O.F. from HF that can't seem to break the habbit of timing out repeaters, you could set your own time-out.

What would be neat would be to have a way to adjust RF power level in a similar fashion, but examining the schematic diagram, it looks like only two power levels are possible.

By the way, the technical manual for the 5100 is finally available. The information is pretty spare. No additonal operating notes or hidden secrets are revealed. It is worthwile for the alignment notes and complete parts list. Call the number in your owners manual to order.
Backlight Control

Effect: manual control of backlight

  1. Hold down the MHZ key and turn radio on
  2. Use tuning knob to adjust brightness
  3. When FUNC is active, the tuning knob will adjust brightness again.
  4. You can restore automatic control by repeating step 1.

Notes: Manual is fuzzy on this feature.

Attributed: Yaesu
Crossband Repeat

(reported as working on 5100 and 5200):

Effect: Enable crossband repeat

  1. Dial up two frequencies you want to crosslink (be sure to pay attention to transmit offsets, if any)
  2. Turn radio off.
  3. Hold down the RPT key and turn radio on

Result: The tone encode/decode flags and the -+ flags will be flashing and the radio will be in low power mode. When either band's squelch opens, the other band is moved into the primary frequency display and the transmitter keys. Audio link appears to be speaker to mike.

Exit crossband repeat mode by repeating steps 2 and 3 above.

Attributed: Yaesu
Transmitter Timeout

Effect: automatically limit transmitter "on" time

  1. Hold down the HIGH/LOW button and turn radio on
  2. Use tuning knob to change the number in left VFO. This number is number of minutes for the timeout timer. The factory default appears to be 15 minutes.
  3. Transmitter shuts off with "Err" displayed in VFO if the time limit is exceeded.

Crossband Audio Enhancement

Effect: unmuffle crossband audio

Connect a 27K ohm resistor between the audio-in and auido-out leads on the data jack (inside the shell of a mini plug, that is). The mic element stays live while in xband operation. It is a good idea to remove the mic from the rig while cross banding if you need/want to eliminate ambient audio.

The P Key on the microphone

I was curious about that "P" key on my FT-5100, so I called Yeasu and they explained the situation. They designed the the mic to accomidate "future products". The "P" key is there to be taken advantage of at a later date by other models. They just did not want to re-design the mic again within a short period of time.

Expanded Receive

Good Effect: enable extended receive coverage
  New range:   128-180MHz and 420-475MHz
 Bad Effect: disable automatic repeater shift selection.

    Warning: This mod does not apply to the FT-5200 as the design
             is somewhat different.

    Warning: You must have a very steady hand or else!  A
             magnifying glass would help too.
  1. Disconnect DC Power cable from radio. ALWAYS!


  2. Remove (6) screws from Top Cover of Radio and (6) screws from Bottom Cover of radio.
  3. Remove Top & Bottom Covers from Radio (Be careful of speaker falling out).
  4. Remove the (2) silver screws on each side of the radio holding front control head to main body of radio.
  5. Carefully pull away (a few inches) the Control Head from the radio body. CAREFUL with the Ribbon Cables.

    There are no numbers on the circuit board so you will have to match up with the diagram below.

  6. On the rear of the Control head locate, Unsolder and remove jumper Pad R4072.
  7. Solder across jumper pads: R4070 R4068 & R4064 (use wire or 0 Ohm resistor)

    If you want to change the D/MR button on the microphone to do Band Switching, now is the time.
    See the next mod.

  8. Install Front Control head, Speaker, Top and Bottom Covers and Reconnect Power to the Radio.
  9. Press and hold [D/MR] [F/W] [REV] Keys and turn on the Radio. Radio will now show 300.000 & 20.000 on Display.
  10. Set UHF Rx Low - Press [MHz] and dial 420.00, press [D/MR]
  11. Set UHF Rx High- Press [MHz] and dial 475.00, press [D/MR]
  12. Set UHF Tx Low - Press [MHz] and dial 420.00, press [D/MR]
  13. Set UHF Tx High- Press [MHz] and dial 450.00, press [D/MR]
  14. Set VHF Rx Low - Press [MHz] and dial 128.00, press [D/MR]
  15. Set VHF Rx High- Press [MHz] and dial 180.00, press [D/MR]
  16. Set VHF Tx Low - Press [MHz] and dial 140.00, press [D/MR]
  17. Set VHF Tx High- Press [MHz] and dial 150.00, press [D/MR]
  18. Set UHF offset - Press [F/W] then [RPT] dial 5.000 press [RPT]
  19. Set UHF tuning - Press [F/W] then [REV] dial 25.0 press [RPT]
  20. Set VHF offset - Press [F/W] then [RPT] dial 0.600 press [RPT]
  21. Set VHF tuning - Press [F/W] then [REV] dial 20.0 press [RPT]
    (VHF tuning step varies by state -- many use 15.0)

Diagram: [there are no tabs in this section - ed]

       Ok, here's where it gets tricky, but so you know, a '|'
          represents a jumper.
                !Ribbon  !                       !Ribbon  !
               !Cable   !                       !Cable   !
           ____!J4002   !_______________________!J4001   !_____________
           !   !________!                       !________!            !
           !                Rear view of FT-5100                      !
           !    ____        Control Head.                             !
           !    !  !                                                  !
           !    !__!     | | | | |                                    !
           !                        | | | | | | | | | | | | |  | | |  !
           !                        R R R R R R R R R R R R R  R R R  !
           !                        4 4 4 4 4 4 4 4 4 4 4 4 4  4 4 4  !
           !                        0 0 0 0 0 0 0 0 0 0 0 0 0  0 0 0  !
           !                        5 6 6 6 6 6 6 6 6 6 7 7 7  0 0 0  !
           !                        1 1 2 3 4 5 6 7 8 9 0 1 2  1 3 4  !
        Stock US Jumpers        After Mod. Jumpers
        R4001                   R4001
        R4003                   R4003
        R4004                   R4004
        R4051                   R4051
        R4061                   R4061
        R4062                   R4062
        R4067                            <- for D/MR button mod

This mod is on Delphi as FT5100.MOD and on

Band Switching and Tone Burst via D/MR button on microphone

Effect: D/MR button on microphone performs band switching rather than D/MR function.

  1. as in above mod
  2. as in above mod
  3. as in above mod
  4. as in above mod
  5. as in above mod
  6. Remove the jumper on Pad R4067
  7. skip above step 7
  8. continue with step 8 above
For tone burst:
  1. as in above mod
  2. as in above mod
  3. as in above mod
  4. as in above mod
  5. as in above mod
  6. Add the jumper or 0 Ohm resistor on Pad R4065
  7. skip above step 7
  8. continue with step 8 above
FT-5100 Copy Memory To Computer

Hello OM!
If you are a happy owner of the YAESU FT5100 and a computer, here you have a nice project. This is how you make a copy of the FT5100 memory into a computer file, then you can have a number of files for different locations, for backup etc. You need a converter RS232<=>TTL and some terminal program for your computer, say the MS-Windows Term.

The FT5100 read and write serial data at 9600bps 8N1.

MIC-pin 1 = serial TTL data input.
MIC-pin 6 = serial TTL data output.
MIC-pin 7 = GND.

I used the MAXIM MAX232 IC for the conversion of TTL level 0/+5 volt, and the RS232 level of +12/-12 volt for the computer.

Turn on your FT5100 while holding down the F/W button, then press RPT for transmitting data from the FT5100 or the REV button for receiving data into the FT5100.

While capture data from the FT5100 into a file, make sure that you get all the control-characters. There are 1277 characters to be saved.

When transmitting data from a file to the FT5100 make sure that your terminal program makes some delay between the characters, or you will get the FT5100 showing an Err-Err display.

Yaesu FT-5100 CAT/Remote Control Mike Interface

I own a FT-5100 and became interested in the Remote Control Mike, not for its wirelessness, but because it can control most of the radio's features via a serial data stream through the mircophone jack.

Although I do not own the wireless mike, I was able to build an interface between my PC and my 5100. It is somewhat similar to the CAT interface I have built for my FT-757 HF rig, but mostly like the interface described in the FT-912R manual (loaned to me via a friend from Yaesu). I have recently been working on a micro-controller based radio controller which I use for transmitter hunts, and other ham related activities, and I plan to allow it to control my 5100 soon, but so far I have only controlled the radio from my PC. When using my PC as the source for the serial data, I used a MAX232 chip for a level conversion between the +/- 12 volts levels on the computer and the 0-5 volt levels on the radio.

The serial data paramaters are 4800 N82. The commands sent to the radio are simple one byte instructions. The RMC mode ON command (16) must be sent before any other command. When the RMC mode is ON, a small LCD "RMC" icon will light on the display (see owners manual under Display). Also, the Vol, Sql, and Bal knobs are disabled when in the RMC mode because they will be controlled via serial commands, but all other buttons are still active.

The commands are as follows:
0  - RPT            12 - CALL             24 - SQL Up
2  - REV            14 - BAND             26 - VOL Up
4  - MHZ            16 - RMC              28 - BAL Right
6  - D/MR           18 - SUB              30 - BAL Left
8  - TONE           20 - PAGE             32 - SQL Down
10 - LOW            22 - F/W              33 - VOL Down
The interface I built simply wired mike port pin 7 to serial ground and pins 1 and 3 each through a diode then together, to the serial source. Note: I am not a hardware person! Use this hardware at your own risk.

          +----1 7-------------- GND 
          |   2 8 6                      (These can be connected to a MAX232
          | +--3 5   +-+-------- SER IN   or the FIF-232C pins 1 and 3)
          | |   4    | |
          | +--->|---+ |
You can wire 1 and 3 together first, then through 1 diode, but that disables the UP and DOWN buttons.

Transforming the Yaesu FT-5100 for 9600 baud

*** Do read these instructions carefully ***
Hello user of a FT-5100. The following instructions describe one possibility to transform the FT-5100 (not tested with a FT-5200) for Packet Radio using 9600 baud.
I want to point out that before starting, you should be familiar with a soldering iron, and have some knowledge in electronics. If not, ask a friend who knows how to handle this. The transformation does not require a genius, but the transceiver does not pardon mistakes.

Let's start:
You will need a schematic diagram, a soldering iron, a capacitor of 100nF, two resistors of 30kOhm, 30cm (1 foot) of 4 wire cable and a 4 pin socket. Open the transceiver. (Attention: you lose your warranty!) Solder one side of the 4 wire cable at the 4 pin socket, no matter with way.
Thereafter, you need to enter the cable into the transceiver. Have a look at the rear side. On your right, you see a fourth, not used exit. It's covered by a small piece of polyvinyl, held by two screws. Unscrew it and you have a clean possibility to get the cable inside.

Doing the transformation at the reception side:
Get the LF at the de-modulator. That's pin 9 at IC MC3372ML (Q404) on the IF unit.
Solder one wire at this pin.
Therewith you are already now able to receive 9600 baud on 70cm and simultaneously, you are still able to work with 1200 baud on 2m or 70cm using the data-connector.
You may also still do phone using the microphone connector.

Doing the transformation at the transmitting side:
First, solder the resistor of 30kOhm at pin 13 of IC MB1504PF-G-BND (Q701) on the 430-PLL-UNIT. Put into series the capacitor of 100nF. Now, solder the second wire at the capacitor. Now, the FT-5100 is nearly ready for transmission. Let's do the PTT switching.
Several tries using the data-connector did not work. What happens to be ok for 1200 baud has to considered disastrous for 9600 baud. But using the microphone jack, it is possible. Open the front panel and solder the third wire to pin 6 of the connector.
When this has been done, all PTT problems are gone.
Last but not least, solder the last wire to ground on each side.
That's all. Not too difficult, isn't it?
Please, check all soldering before the re-assembly. This may avoid later trouble.
The transformation is done. Now, you just need to connect the TNC. Because everybody connected his socket in a different way, have a look at the TNC manual how to connect the right pins. Now you may do your first try.

In general:
After the re-assembly, it should work immediately with 9600 baud, of course your TNC has to be set-up properly. I owe an USCC card with 3 channels and I am using this set-up without trouble. TX-delay may be adjusted till a minimum setting of 7ms. You should always keep in mind, it's no data transceiver, it's still a phone transceiver. Do not expect superb results.
Nevertheless, until today, I do not see a disadvantage compared to commercial 9600 baud transceivers.

You may not declare me being responsible for any destruction due to this transformation. It should show you hoe it is possible to use a FT-5100 for 9600 baud. I never had problems, why should others...

This transformation is probably not the very last you may get out of this transceiver. I am always looking for other possibilities to improve it. Have fun and a lot of success using 9600 baud.

Yaesu FT-5100 on 9600 Bauds

There is also mention of the Yaesu FT-5100 dual-band transceiver being 9600 baud ready in the February 1994 QST (Packet Perspective p.98). Stan WA1LOU writes that he spoke with Chip Margelli K7JA of Yeasu Customer Service. The bottem line is:

Yes the FT-5100 will do 9600 baud out of the box. The Japanese manufactures have agreed upon a standard. The spec calls for a transmit signal input level of 2 V p-p at 10 kohm. The receive output as 300 mV p-p at 1 kohm from 50Hz to 5 kHz, + or - 3 dB. All transceivers that conform to this standard will provide a 6-pin miniature DIN jack for the 9600 baud modem interface. However the FT-5100 was developed prior to the adoption of the standard, so it does not feature the DIN port. According to Chip, future Yeasu radios will feature the 9600 baud standard port and optimization. Icom and Standard are mentioned as other manufactures adopting the standard.

Stan says they [QST] will "review the capabilities of each in a future issue."

[the above is paraphrased from QST]

I visited the HRO store in Sunnyvale and looked at the FT-5100. There is what seems like a miniture jack connection on the back of the radio, not a DIN as the future standard will provide. I didn't ask to see the manual from the sales people. The questions I would liked answered are the same as Walt and John expressed in their missives.

Think about it - 9600 baud is now in the reach of everyone. Especially think of the impact it will have on the 9600 baud pacsats. The microsats required at least one all mode radio for the PSK downlink which is not an inexpensive radio. Now, if the Icom or Yeasu radio can do both the up and down link for $700.00 more people will (hopefully) just on the bandwagon. Don't flame me for the price, I for one have been struggling with 9600 baud trying to convert my Kenwood TR-751 and TR-851. I still don't have it right and I have had to repair my TR-851 twice after the PLL went out and I zapped the FM chip. How can you advocate others to get on the air will 9600 baud when you tell them to open up and possibly zapp their $700.00 radio?

General Review (with 5100 slant)

Since Yaesu's advertising has already made the good points known, I'll concentrate on the warts and shortcomings.

Dual In-Band Receive: works as advertised except for sensitivity. The "main" receiver works very well. The "sub" receiver works very well when tuned to the opposite band from the "main" receiver. When tuned to the same band, the "sub" receiver suffers from slightly lower sensitivity in the ham bands and greatly reduced sensitivity out of the ham bands.

There is a 2m VCO/PLL/IF and a 70cm VCO/PLL/IF. I assume that dual in band receive is done with the opposite band's receiver. This would explain the poor sensitivity, but it sure raises some questions about how the duplexer works.

I expected a type "N" connector, the radio came with UHF.

Control wart: (are you listening Yaesu?) You can only transmit on the "main" (ie. left) side of the radio. When both 2m and 70cm receive are active, you change bands with the "BAND" button. This swaps the left and right displays. When dual in-band receive is active, the "BAND" button changes both the main and sub receivers from 2m to 440 or from 440 to 2m. Arrrgh!!!! I would prefer a "SWAP" button to swap left and right regardless of mode. (The "SUB" button is used instead.)

Automatic backlight dim: works as advertised but the backlight level under low ambient lighting is WAY too low. Manual control is the best solution.

DTMF page: works as advertized, but the *&%$#@ thing insists on "ringing" like a phone EVERY time it receives the page sequence. This means that you have to co-ordinate with the other station to turn the *&%$#@ DTMF stuff off at the same time or tolerate the "ring" at the start of every receive.

CTCSS decode: squelch opens quickly when normal CTCSS decode (an option) is enabled. There is a CTCSS page function that has a distinct delay between receipt of carrier with CTCSS and open squelch. I don't yet understand the use of this "feature."

There is no SCAN button on the front panel. Scan is initiated by holding the up or down button of the mike down for two seconds. The scan is blindingly fast when compared to the Alinco 590 that I used to have.

Memory: memory is divided into four "banks." Two for VHF, two for UHF. Only one bank can be active for each receiver. I consider this an advantage, but you may not. There are two obvious (to me) uses for this configuration. First, you can store frequencies for different uses in different banks. Second, you can activate one 2m(440) bank in the main receiver and one the other 2m(440) bank in the other receiver and scan them simultaneously.

Heat management: After seeing the HUGE heat sink on the back of the Alinco 590, the Yaesu 5100's sink seems too small. In a key down experiment, the heat sink of the Yaesu got almost too hot to touch before the fan kicked on. If I were planning to run a packet station, I would definitely look into some extra forced air over the back of this one. As it is, I'm a bit concerned about how hot it will get mounted in my dashboard. [Others people don't seem to have this problem.]

DTMF Decode and Scan: If you have CTCSS decode (an option) enabled on a memory and you are scanning and there is activity on that frequency but without the correct CTCSS tone, the 5100 stops scan, flashes the strength meter and then continues scanning. It is slower than normal scan, but still quite fast.

DTMF decoding

Effect: display decoded DTMF tones

Ed Note: this works on the FT-530, but not on my 5100. I'm including it here on the chance that it works on the 5200. Please try it on your 5200 (or 5100) and tell me if it works for you.
  1. Select frequency and turn on the code squelch
  2. Press Function-Page(Code) to select a code memory
  3. Dial up to memory #7 [the 5100 won't do this]
  4. Watch the dtmf's scroll by as they are heard by the radio!
FT-5100 Random reset fix

March 19, 1995

Hi everybody.

I've owned a Yaesu FT-5100 for about a year and a half and I'm delighted with the rig. Recently, I've experienced two mysterious resets of the rig that have required complete reprogramming of the memories. Since I did the extended receive mod, it also requires reprogramming of the upper and lower RX and TX limits for both VHF and UHF. Both resets occured while using the rig in my Chevy S-10 4x4. The mount I use in the S-10 is a cellular style single post mount that does a nice job of not being in the way, but is prone to vibration of the radio. In my work vehicle I use a Motorola floor mount that does an excellent job of holding the radio sturdy.

Since I brought the rig into the house to do the job of repro-gramming, I decided to open it up and look for any sign of loose hardware or broken cabling. I found that the flat printed cable that runs between the main chassis and the control head circuit board (those that have done the extended RX/TX mod and/or the microphone D/MR button to band change mod will know what I mean) was slightly deformed. Close investigation revealed that there are several metal tabs protruding through the board that are from the metal frame that holds the LCD in place. These tabs are bent slightly to lock the frame to the circuit board. Unfortunately, the flat cable folds and presses tightly against two of the tabs along the edge of the cotrol head circuit board. I noticed that at least one conductor may have been exposed by pressure on the tab. This probably resulted in this line being grounded at some time, a situation that was likely aggravated by vibration in my S-10.

My fix of this problem was to put a small piece of electrical tape over the sharp corner of each tab, then a larger piece that entirely covers the tab and adheres to both the circuit board and the inside of the bezel. Now there is a double layer of tape between the tab and the flat cable, also you may want to put a layer of tape on the flat cable for additional protection. As near as I could tell, the wire was not broken (whew!) by the contact.

Now time will tell if this was the cause my mysterious resets or if the trouble is elsewhere. One thing I am certain of is that I probably headed of some other problem by doing this, like an all expense paid trip for my radio to Yaesu USA! If you are unsure of how to access this area of your FT-5100, complete details can be found in the extended RX/TX mod sheet available on a lot of BBSs.

If nothing else, send me a packet message and I'll send a copy your way.


It's been over three and one half years since I applied this fix and so far (knock on wood!) the problem has not re-occured. I've not seen any other mention of this problem, so perhaps this was an isolated case.

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