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Yaesu FT100 FAQ / Knowledge Base

Maintained by Lee Devlin, K0LEE

General Links for the FT100:
View the Archive of Yahoo Groups FT100 mailing list.  There was a mailing list for FT100 users which included an archive of messages but Yahoo discontinued that service and this archive is all that is left of it. 



AM Settings

Gary Mitchelson, N3JPU, has done some interesting tests with the AM settings and found some settings that work much better than the defaults. The parameters that sound the best are: PO set to 25, Mic gain to 40 to 50 and Carrier Level set to 225 (F51 menu).

Most owners who have had difficulties with AM audio quality  have reported that the 6k HZ option AM filter (p/n XF117A) is an absolute necessity for both transmitting and receiving in AM mode.

AT-11MP Autotuner

Some owners have opted to purchase the AT-11MP auto tuner from LDG Electronics. This is available in either a kit or assembled format and does not suffer from the CAT/FC-20 limitations.

There is an accessory for the FT100/D called the OTT or 'One Touch Tune' available from W4RT.com that allows you to use the 'Tune' button on the FT100 to control the tuning function of the AT11 directly from the FT100.  It also allows you to maintain the CAT compatibility which is something you normally lose with the FC-20 autotuner.


The ATAS-100 is a motorized vertical antenna for the FT-847 and FT-100 radios. It covers the 40m through 440 bands. It is intended to be used mobile, or can be used for a fixed station with an appropriate ground. Yaesu sells a kit, the ATBK-100, for those wanting to use the ATAS-100 at home on VHF and higher bands. 

The two radios that support the ATAS-100 send a DC voltage on the coax to cause the antenna to grow longer or shorter, depending on the band you're tuning for. You can't use the FC-20 Autotuner and the ATAS-100 at the same time. Of course, you do not need both.

The use of the antenna is covered on p. 62 in the owner's manual for the FT-100. In it they discuss the possible need to adjust the length of your coax (to "eliminate the possibility of adverse transformer action in the 50 ohm cable"!). 

According to the values of the voltage divider circuits shown in the technical supplement  +8.4V applied to the coax causes the ATAS-100 to retract, and +10.0V or more will cause it to extend.    There is a voltage range between 8.4V and 10.0V which will cause no motion to occur.  It has been reported that the radio asserts a voltage in this range for approximately 1/2 seconds after a manual or autotune event.

The ATAS antenna is 56 inches fully retracted and 63.5 inches fully extended.  A trunk lip mount like the Diamond K400 adds about 2 inches to the overall height. A magnetic mount should not be used with the ATAS-100 without an auxiliary ground connection. Otherwise RF feedback may damage the radio. The whip portion of the antenna extends 35.5 inches above the base and the whip is 2 mm (.080 inches) in diameter.

Yaesu has received a patent on the ATAS-100 which you can read on the Delphion web site.

If you need to have your ATAS100 repaired, there is a fellow ham, Tom Dailey, W0EAJ, with a repair business in Denver,CO called Tom Dailey's Vintage Radio Repair that may be able to help you.

ATAS-100 Autotuning

The tuning behavior of the ATAS can cause confusion unless you understand the algorithm it follows to find a good position. Normally, if the ATAS is installed correctly and it successfully autotunes itself, it will always go in the correct direction when you press in the TUN button for 1/2 second once it has found its first good match. However, it the ATAS cannot find a match, it will run all the way to one end, turn around, and start over. This process can take a while since the antenna runs 'open loop' when it loses its position. Since it doesn't know which position the antenna is in unless it makes its own successful match, it needs to be sure it has gone all the way to the end before reversing, which can take a very long time.

Anytime it is not sitting right where it found a match all by itself, it can end up starting out in the wrong direction next time. Examples would be if you manually do even just a little fine tuning, or if you interrupt autotuning and change bands. Then the rule is very simple: it starts the next autotune by going in the last direction it was going in, which is not necessarily right. If it's going in the wrong direction, the antenna will move all the way to a stop and then it will have to turn around and start over again after a long delay. If you recognize that it's going in the wrong direction, you can avoid the long delay by aborting the autotuning process by hitting the TUN key momentarily, then manually move the antenna just a little (with the PTT and up or down keys) in the correct direction, and then recommence with the autotuning procedure.

ATAS-100 Disassembly

Please refer to the ATAS-100 Technical Supplement prior to using this section.


The following procedures can possibly void your warranty.

**************Use these procedures at your own risk.***************

Of course I am NOT responsible for any damage caused by disassembly, or any other general messing around with this antenna or your radio, enough said.


(And a little on how it works)

The stainless steel whip is mounted on top of a loading coil (under the rubber boot). The coil consists of copper wire wound around a "grooved" fiberglass rod. Part of the reason the antenna is guaranteed to work on 40,20,15 and 10m HF bands but not on 12,17 and 30m is that the spacing on the coil is wider at the resonant points on the coil on the "primary" bands allowing easier tuning.

The loading coil slips into the "body" of the antenna where spring loaded contacts make the necessary connections. At the base of the coil and rod is a Teflon disk that makes sliding contact with the inside of the tube and is threaded for the brass "screw" rod that raises and lowers the coil.

About 7" below the contacts is the motor and clutch assembly (at the middle rubber cover). Two wires run from the motor to the controller board that is mounted on top of the base unit.

The base (matching unit) consists of a chromed top cap which includes the mount for the motor controller board. Below this is a 3" black plastic tube that forms an insulator. At the bottom is the threaded chromed base cap that is where the SO-239 connector screws in. This base assembly is secured with pins and would be hard to dissemble without damaging.

Inside this is an RF choke coil (I'm not sure if it is air wound or on a torrid) that makes this whole antenna DC grounded. This protects the radio from damage from whip contact with power sources, static build up, etc. The coil also helps with matching the antenna and contributes to the high Q of the design.

Connected to this is a capacitor that leads to the center pin on the SO-239 receptacle in the base. This capacitor is also part of the "broad band" matching network.


1. Extend the antenna fully (40m).
2. Remove from vehicle and take it to a clean work surface.
3. Remove the whip for ease of handling.
4. Slide up the 2 rubber covers exposing the screws.
5. Remove the 3 lower screws above the base.
6. CAREFULLY remove the base by gently pulling down while using a slight rocking motion (the resistance is from a O ring).
7. Carefully withdraw the base assembly while noting the routing of the motor wires.
8. Unplug the micro connector from the motor controller board (the red and black wires that leads to the motor-clutch assembly), and set the base aside.
9. Mark on the shaft the location of the bottom of the boot, then slide the boot upwards exposing the loading coil.
10. Remove the remaining 6 screws on the antenna.
11. Carefully slide up the loading coil which also removes the motor-clutch assembly (be careful with the alignment pin).
There is more than can be disassembled, but the above steps are all that is needed for most maintenance and repairs. While you're in there, clean the moving surfaces up and oil with a light oil (like mineral oil) that won't harm plastics while taking care not to contaminate the contacts, coils and connections.


1. Basically reverse the above procedure.
2. Be careful to make sure the alignment pin (about 7 inches long) from the loading coil to the motor-clutch assembly is in place.
3. Pay special attention to the routing of the motor wires to prevent pinching between the motor controller board and motor-clutch assembly.

Contributed by Cliff Holloway, N0HC

ATAS100 Manual Tuning

The ATAS100 can be tuned up and down manually by holding in on the PTT switch and using the UP/DOWN keys on the front of the radio.  If you thought it meant the UP/DOWN keys on  top of the hand mic, you're not alone, as several others have made the same mistake and the manual does not specify which UP/DOWN keys to use.  It has been noted that the P1/P2 keys on the mic will cause the antenna tune icon to come on if you push them while holding the PTT, but they do not actually move the antenna.

ATAS-1/ATAS-2 Settings

Menu item 61 is has several settings for controlling the way the ATAS100 antenna works.  In the user manual, there are several errors describing this function.  On page 14, the instructions are correct and the easiest way to remember the correct settings are:  ATAS-1 = one antenna ; ATAS-2 = two separate antennas.  In other words, if you're using the ATAS100 on all bands (with a duplexer), choose ATAS-1.  If you are using the ATAS100 for HF only and a separate antenna for VHF/UHF, use ATAS-2.  Page 62  in the manual is backwards from this as is page 94 which recommends that a duplexer is required with ATAS-2.  The newer manuals may have corrected these errors but as of manual revision E08981003  the mistakes were still present.

Another user noticed that when either of these selections are made, the radio will not transmit on the 80 or 160 meter bands so don't forget to switch menu item 61 to OFF (or to Tuner) when you switch from the ATAS100 to another antenna.

ATBK100 Ground Plane Kit

The ATBK100 is a kit consisting of 3 ground radials for the ATAS100 intended to make it suitable for use as a base antenna.  Although there is no information available on the Yaesu website about the ATBK100, this US$90 kit is supposed to supply a ground plane for the 50 MHz, 144 MHz, and 430 MHz bands.    One owner responded that he was able to get the antenna to work on other HF bands by adding two 20-foot lengths of wire to the ATBK100 to act as a counterpoise.


Audio Settings (improving transmitted audio performance)  

Bill, N4XEO, has contributed the following advice for those who are not satisfied with their audio reports.  First, make sure the rig's chassis is grounded to the frame of the vehicle and that the rig is powered directly off the battery with minimal voltage loss through the power cable.  Secondly, make sure that the voltage is sufficient for the rig.  The specifications call for 13.8V DC and so if you're not running the engine, it's likely that your voltage won't run the rig correctly for very long.  This will be apparent when operating with the engine off as the battery voltage begins to sag down around 12V.

Here are some of the settings Bill recommends that have worked for him and others to improve the audio:

Menu Item Description Value
25    Mic Gain (for SSB and AM modes) 40
26    FM Mic Gain 45
27    Compression Level 40
33    FM Deviation 5
62    RX LSB Carrier +050
63    RC USB Carrier +050
64    TX LSB Carrier -200
65    TX USB Carrier -200


The CWID feature appears to have a bug.  It sends out the 'W' as a 'U' in Morse code.  The CWID feature, when enabled, transmits a CW identifier every 10 minutes when the radio is operating in ARTS mode.  Here is a set of instructions on how to test if your radio is affected:

Go to menu item 11 and enter a CW ID string with some W's in it. To do this, press Select knob and use the main dial to select the characters. Press the Select knob to advance one character. Program all 8 characters using the Select button to advance.  When you get them all programmed, press Select again and the radio will playback the ID you've stored.  Use a tape recorder unless you think you can copy comfortably at 35-40 wpm.  If you want to hear it on the air, proceed with the following instructions.

Go to menu item 10 and enable the CW id during ARTS operation.

Set the radio to a clear simplex FM frequency.

Press the FUNC key until you get to screen 3 which shows TON DCS and ART. Enable ART.

Listen on another radio. The DCS code will be sent every 15 seconds and the CW ID will occur every 10 minutes. Again, use a tape recorder, as the ID comes across at about 35-40 wpm. I have a little recorder that will allow me to record at 2.4 cm/sec and play back at 1.2 cm/sec so I can listen to the CW at a more comfortable 18-20 wpm.

Here is an example of the W bug in the CW ID feature in .wav format.  It was supposed to send W8UWT, but sent U8UUT instead.  The whole message is:  DE U8UUT K with a small DCS beep at the very end.

Band Data Pigtail Pinout

The following data was contributed by Jack, W3TMZ.  The Band Data pigtail can control a VL-1000 amplifier when set internally to control an amplifier.   The normal mode is for the CAT/Tuner function, but it can be rearranged with an internal jumper (shown on page 19 of the manual) to control an amplifier.   If you're curious about how the signals work in that mode, the table below shows the logic depending on the band selected.  The images to help explain this better are shown here

Yaesu FT-100D Band Data Output map H=4.4 vdc L=0 vdc

Band1.8 3.571014 1821242850144440

CAT operation

The CAT functions require the use of accessory CT62 which is a custom cable that connects to the ACC pigtail and has a built-in level shifter.  The CAT functions of the FT100 are supported in the following programs:

The following are logging programs that support the FT100 CAT functions:


The ATAS100 is designed to tune on all the bands on which the radio transmits including 2m and 70cm.   This requires a duplexer like the Diamond MX62M or the Comet CF706 to connect the VHF/UHF and HF  pigtails together.  (The actual cross-over frequency between the pigtails is 70.5Mhz.)   However, many people prefer to use a separate antenna for the VHF/UHF bands since those antennas typically cost about the same price as a duplexer and usually have some gain whereas the ATAS100 has no gain on VHF/UHF.  Also, with separate antennas you don't have to worry about retuning when switching between VHF/UHF and HF.

A consideration when using a duplexer is that the DC voltage for tuning the ATAS-100 is supplied through the HF pigtail.  Therefore, this pigtail must always be connected to the ATAS for tuning purposes.  Also, it must not be capacitively coupled  inside the duplexer or it will block the DC motor control voltage.

Extra Bands

You may have noticed two extra bands appear while moving through the normal ham bands using the up/down keys.   Apparently, the rig remembers an extra band for HF and another for V/U portions of the radio.   If you tune outside a normal ham HF band either accidentally or intentionally, you'll notice that this band will now appear in a list of bands as you use the up/down keys.   The same is true for the V/U side of the radio.   For example, if you tune to the weather band at 162 Mhz, it will appear in the list between the 2M and 70cm bands.    Previously, it was thought that once these bands were tuned, they couldn't be removed from the list without resetting the radio but Joe, K0OG, has informed us that the extra band may be moved by putting one in the AM band and another in the 900MHz range. That leaves all the ham bands grouped together, bracketed by the other two frequencies.  

Factory Modifications

There are two common modifications retrofitted to the FT100s manufactured prior to 2001. (If you want to find out when your unit was manufactured, click here). These include the fixes for the Intermittent High SWR ICON problem and the VHF/UHF thermal sensor modification to enable the fans in the V/U receive mode.  Although there had been reports that new radios included the SWR mod, the mod  has been through several iterations and it's possible that even radios purchased today do not include the 'final' mod with the screws, but rather just the copper tape held on with adhesive.   The thermal mod is done on an 'as requested' basis since Yaesu feels that keeping the fans off in V/U receive poses no threat of overheating the radio.


FC-20 Autotuner

The FC-20 auto tuner is available as an accessory for the FT-100.  The FC-20 was designed specifically for the FT-847 and FT-100 and is intimately mated to them. The FC-20 is capable of matching a SWR up to 3 to 1.  It features 100 memories that memorize your favorite frequencies so that when you return to them, the unit can "instantly" tune to a frequency without having to evaluate the SWR as it tunes.

People have identified two limitations to the FC-20, the matching range and the inability to use both CAT control and the tuner simultaneously. If you don't need a wide matching range and don't use the CAT control with the radio, then the FC-20 is reported to operate very smoothly and is well integrated with the radio.   If these limitations are important to you should consider the LDG AT-11 autotuner.

Firmware Upgrades

A common question asked regarding the FT100 is whether or not its firmware can be upgraded to add some missing feature in the future such as memory management via a PC or keypad frequency entry.  Unfortunately, the design of the FT100 does not allow for this kind of feature since the microcontrollers are not flash-based, but rather OTP (one-time programmable) devices or even mask-based in later production runs.   They can be removed and replaced, but this takes special SMT (surface mount technology) soldering equipment.

There are three microcontrollers in the FT100:

The FT100's main processor, mounted on the controller unit, is a 32MHz, 80-pin, 16-bit CPU from NEC (P/N UPD78P4038).  

There is also an 8 MHz, 48-pin, 8-bit microprocessor on the controller unit made by Fujitsu (P/N MB89P133PFM) that appears to be the one that does the electronic CW keying since it only has a few inputs and they connect to the 'key1 and key2' on the back of the unit.  It uses a few of its serial pins to communicate with the main CPU.  FMI see: Fujitsu MB89P133PFM

The display board has a 5 Mhz, 80-pin, 8-bit NEC microprocessor (P/N UPD78P054) and that communicates with the main CPU via a serial link.  


The FT100D is an updated version of the original FT100 that includes the following changes: It has a larger built-in speaker, a high stability crystal oscillator, a 500 Hz CW filter, and a CTCSS decoder. All of these features except the speaker were previously available as field-updateable accessories to the FT100.  The FT100D was announced in May, 2000 and is currently shipping.


Intermittent High SWR ICON

Some owners have had trouble with the HIGH SWR Icon appearing while attempting to transmit on certain bands.  The most common advice is to make sure that the antenna mount  and radio are properly grounded via some heavy braided material to the vehicle chassis.  Some owners have had success in using clamp-on ferrites with the separation kit cable wrapped several times around the ferrite to block common mode current from getting back into the rig.  Ten meters seems particularly prone to the problem.   Changing the feedline length has also helped in some cases, but this seems to move the problem around more than solving it at the root cause.  Also, some owners have found that fixing the grounding of the LPF board by adding solder around the screw holes and in some cases tightening the screws or adding star washers was sufficient to make their grounding problems go away.

However, there is a very effective modification that has worked in every case.  The mod involves fixing the grounding in the coax sockets on LPF of the radio and a metal shield on the Main Unit.  A degradation in the LPF grounding can cause the rig to break into oscillation (even at lower power) causing the HIGH SWR icon to appear intermittently even with a good antenna match on the higher HF bands. The mod will eliminate this oscillation and the high SWR reports.  Here is a page with links you can follow to several high resolutions pictures of the factory installed mod.  The adhesive copper tape has been replaced screws or clamps that are attached to the casting web.  

The SWR icon with an 'X' next to it indicates that the SWR is out of range.  If you see an SWR icon with an 'O' next to it flash momentarily, it is an indication that the antenna has finished tuning and the SWR is 'OK'.

Keypad Frequency Entry  

There is no way to key frequencies into the FT100 via the microphone's numeric keypad (standard on US models).  That numeric keypad is only used for touch tone encoding when the PTT is held.  However, John Hansen, W2FS, has designed an auxiliary keypad called the Millenium QSYer  that can be used to enter frequencies from an external keypad. The cost is US$70 for the kit or US$95 for the assembled and tested unit. It can also be used with  the Yaesu FT817 and Icom IC706 mobile radios.

Manual Revision Numbers

The manual revision can be determined by the part number of the manual.  This number is located directly below the barcode on the back cover of the manual and will have a format like 'E08981003'.  The number on  the lower left-hand corner of the back cover with the format such as 9907V-EY is the printing lot number and does not contain information relevant to the revision of the manual.

Another common question asked is where one can get a copy of the owner's manual, preferably on line.  You can find it  here.  There is also an FCC site that has manual, schematic, and other information related to the submission for approval by the FCC.  Unfortunately, this information is quite out of date since a product is normally submitted to the FCC well in advance of its actual availability and the manual is often just a rough draft of the finished manual.  An exploded view of the rig can be found  here.  There is also an effort underway to make the alignment procedures available.

The FCC site can be found at: http://www.fcc.gov/oet/fccid/.  To get the information, use the Grantee code K66, and the equipment product code FT-100, and select View Exhibits.   Here you may view schematics, photos, block diagram, parts lists and a PDF version of the user manual.  The manual shown appears to be only a rough draft with 36 pages of information vs. 108 in the finished manual.   It contains no illustrations.  The manual and schematics were scanned and converted to .pdf and you will find resolution of the schematics is not high enough to be usable.  It is highly recommended that if you lost your manual or bought a used radio without one, that you contact Yaesu parts (contact information is given at the end of the FAQ) and purchase a new one.

Memory Programming

There are a few common difficulties in programming the memories.  The radio has a mode to allow rapid tuning through the memories by skipping unused memory locations.  This feature must be disabled to store frequencies in an unused memory location.  To disable it, place the rig in memory mode by pressing the VFO/M button until MEM is shown in the display.  Then hit the STEP key to enable or disable the vacant memories selection.  Reverse the procedure with the same sequence.  Turning the SELECT knob will help you to determine if the radio is in rapid mode  if you see it is jumping over unused memory locations.

Another difficulty is getting the memories stuck in a particular memory group.  The main memory [1-300] is divided up into 6 separate 50-memory groups.  You can restrict tuning to a single group by pressing in on the SELECT dial for 1/2 seconds while in MEM mode.  You reverse the procedure with the same sequence.  You will see an GCH appear in the  lower left hand corner of the display if you are locked into a particular memory group 1 through 6.  Pressing the SELECT for 1/2 seconds will put it back in memory channel mode and it will display MCH in the lower left hand corner.  If you are not careful and only press the SELECT momentarily, it will put you in VFO mode and you'll have to press the VFO/M key to get back into memory mode.  This is not explained correctly on page 71 of the manual.

There are no provisions for alpha numeric labeling of the memories in the FT100.

Mic Buttons

The microphone MH36B has a complete set of numeric buttons but they cannot be used for numeric frequency input.  They can only be used to send DTMF tones in FM mode by holding in the PTT and simultaneously pressing the numeric sequence.  There is no audio feedback provided to the user while sending the tones.  There are also 4 buttons labeled A, B, C, and D but there is no documented use for these keys.

Microphone Adapters

In order to more easily adapt a desk or boom microphone to the FT100, you can order accessory AD-100-8 adapter from Bob Heil.   This converts the RJ11 (6 conductor telephone style) microphone connector to a more standard Yaesu 8-pin mic jack.  The cost is U.S.$24.99.

Yaesu also released a version of an adapter cable called the CT-69 which is an RJ11 to 8-pin microphone adapter that is available for U.S.$30 list and  it is available for $25 at www.powerwerx.com

Mobile installations

Several owners have been posting pictures and web pages of their mobile installations to give others some ideas on how they might do their own mobile installation.  Please see the links below for examples of various mobile installations.

Lee, K0LEE Dodge Durango Installation
Rainer, SM5LBR Volvo installation
Ian, Vauxhall Arena Van installation
Paul, K0RWU, Olds Cutlass Supreme remote head over rear view mirror installation
Bill, N4ATS installation in 1999 Escort in-dash FT100 and through trunk installation of ATAS100
Dave, N4TAJ, Dodge Durango Installation  
Kevin, WM0F, Ford F100 Installation
Keith, G7DNT/M3DNT  VW Bug Installation
KG5U Saturn SC2 installation
Barry, W4WB, Chevrolet Blazer installation
Yahoo Groups files section with several sets of mobile installation pictures.

Modification for out-of-band transmission

Here is a freeband modification page with a picture and instructions. The mod works for both the FT100 and FT100D. It will not allow you to transmit on the 220 Mhz band.

You can find a text document for the freeband mode that appears to be from a Yaesu Document here.

Also, check out www.mods.dk site with more details and some pictures as well as mods for many more radios.


Power Connectors/Line Filters

An excellent source for power connectors can be found at www.powerwerx.com.  They carry the OEM connectors and shells for the FT100 (and other rigs) as well as the Anderson Powerpole connectors which allows you to make up cables so that it's easier to interchange different brands of radios with various power supplies.  They also carry line filters to reduce alternator whine from the DC power source.

PSK31/SSTV/ Soundcard programs with the FT100

Operating soundcard programs like PSK31 is accomplished by using the DATA Jack on the rear panel of the radio.  The definitions of the jack as provided on pages 20 and 21 of the manual are:

Pin 1: Data In (AFSK input for soundcard)
Pin 2: GND
Pin 3: PTT
Pin 4: 9600 Baud out
Pin 5: 1200 Baud out (audio out for soundcard)
Pin 6: Squelch

It is necessary to build a circuit or purchase and interface prior to using soundcard programs.  There are several sources on the web that describe these interface circuits.  You can find them at:


If you would prefer to purchase an interface, you can find them at:

The cable for the DATA jack is the CT39 and costs U.S.$10 from Yaesu.    Jon, WA2NKF, put together a  diagram on how to interface a soundcard to the FT100 using the CT39 or other 6-pin DIN connector.  It is a very simple interface with a minimal number of external components to enable the PTT.

Sandor, KG4FET, has had good success using the FT100 for PSK31 and recommends using the USB mode (not RTTY mode).  Playing around with RTTY or AFSK mode settings on the FT100 will only cause confusion.  Sandor also used 1:1 600-ohm isolation transformers on the TX and RX lines as well as an opto-isolator for the PTT.

Problems with FT100 radios

Several owners of the early FT100 radios experienced failures of the V/U output transistor. The word from Yaesu was that solder flux  left on the board was to blame. Another common issue is related to the Intermittent High SWR ICON problem discussed elsewhere in the FAQ. Overheating on V/U receive was also an issue on units manufactured prior to 2001 and can be fixed with a thermal sensor modification that Yaesu has applied as a retrofit. The ATAS100 antennas seemed to have a rash of early failures where they refused to move after a while. This appears to have been corrected with a new H bridge that drives the motor.

Repeater Offsets

The repeater offsets are determined by the values set in menu items 40-43.  If you need to program a memory that has a non-standard offset, use the DUP memories since the repeater offset is not stored with the other parameters in the standard memory locations (1-300).

Frank, PA4FR, adds this information as an alternative to using DUP memories:  FT-100 ARS (automatic repeater shift) might be activated for 2m and 70 CM bands separately. ARS is default enabled for both bands. When ARS is enabled, any (!!) manual change to repeater offset or repeater on/off setting is overridden when you change the channel. The is actually logical, since ARS defines a certain repeater offset and a certain set of repeater channels (band-plan). Any changes that violate these ARS settings are "reset" when changing channel. This is especially confusing in Europe, where the 70CM repeater band-plan differs per country and therefore the "pre-programmed" repeater band-plan often is not correct.


Knowing this "strategy" behind ARS operation makes figuring out a solution very simple: just disable ARS (most likely on 70CM only).  Then set one of the VFOs into the 70CM repeater band and enable repeater shift. YES: repeater shift setting will be stored with 70CM VFO setting and will remain active when changing channels.  Such a channel can be stored into memory and repeater shift and offset will be stored with it.  (Note that the repeater-shift on/off setting is tied to the VFO and band, just as it is with other settings like APO)

So, it's not a firmware error, it's just meant to be like this.

RF Exposure

Because the antenna is so close to the occupants of the vehicle with a mobile rig, some owners have expressed concern about whether or not the installation of the ATAS100 would comply with the FCC's guidelines on RF exposure.  I had my ATAS mounted on the corner of the hood which puts it about as close as possible to the driver.  Here are the results of my RF field strength measurements using a Haladay HI3004 RF field strength meter when running a 100W FM signal as measured in the front seat near the driver's head:

Band    Field Strength

10M ~ 8 V/m
12M ~ 20 V/m
15M ~ 15 V/m
17M ~ 15 V/m
20M ~ 12 V/m
40M ~ 16 V/m

Outside vehicle, the field strength was about 30V/m when measured 2M horizontally from the antenna.

The FM signal was about twice the strength of a typical SSB signal since it puts out 100W at 100% duty cycle whereas SSB was about half of that. So the readings above are about 2 times higher than you would expect in normal HF operation.

The maximum exposure limit for a controlled environment is 61.4 V/m at 30-300Mhz and it rises as the frequency decreases according to the equation 1842/f. For an uncontrolled exposure, the 30-300Mhz limit is 27.5 V/m and increases according to the equation 824/f as the frequency decreases where f is  frequency in MHz

You can see from the readings that the fields inside the vehicle are well below the maximum allowable for a controlled environment such as a ham station, and even meet the more stringent limits for an uncontrolled environment. Combine that with the fact that the measurements were taken at 100W with 100% duty cycle, and you can see that this antenna arrangement is considered to be safe by FCC standards.

Technical Service Notes

Many FT100 owners have asked if there is a comprehensive list of Technical Service Notes (TSNs) available for the FT100. Yaesu's policy is not to release this information unless asked for by an individual owner who requests to know what specifically was done to fix his rig. Accompanying this information is a document that states that the information cannot be shared. Hence, we don't have a means to compile a comprehensive list for the FAQ.

Transmit problems on 80/160M

Some FT100 owners find that they cannot transmit on any bands below 40M.  This is almost always a result of having menu item 61 set to either ATAS-1 or ATAS-2.  Since the ATAS autotuning antenna only works with bands 40M and above, the FT100 will refuse to transmit on 80 or 160M if you set it incorrectly.  To get around this, you need to set that menu item to Tuner or 'OFF' if you're not using an ATAS antenna.

S-Meter Anomalies

Several owners have noticed that the S-meter on the FT100 tends to be somewhat stingy, particularly with FM repeaters.  Many radios will give 60+dB readings on local FM repeaters whereas the FT100 will rarely register more than an S-9.  Some responses to the FT100 mailing list indicated that the FT100 was correctly reporting signal strength whereas all the rigs that give readings such as 60+dB were overloading and going into limiting.  If you would like to make the S-meter more sensitive, here are the procedures:

First off, tune the radio to receive a strong signal from a local 2M FM repeater.

Next, to get into the alignment mode, turn the radio off, now press the [A], [B], and [C] keys, and hold them in while you turn the radio on.  Now press and hold the [FUNC] key, as you normally would to get into the Menu. You'll find that the Menu is now different.

Rotate the selector knob until you find "F-07 [S FULL SCALE]" on the display. Make a note of the current setting of this item, so you can go back to it if you want to. Now adjust this item just like any other Menu item, by rotating the main dial, until you get a full scale reading on the S-meter.

There also is an adjustment of the 144 MHz RF Gain (F-01) and the 144 MHz IF Gain (F-05). Perhaps a little adjustment to the RF Gain would help with the weak repeaters. Whatever you do, make a note of the original settings of these items. Adding too much front end gain can degrade the intermodulation performance of the receiver section. Also, if you change the RF or IF Gain, the S-meter indication will change, too.

Press the [FUNC] key to exit the alignment mode.

If you have the equipment for it, you can more accurately adjust the s-meter  by injecting a 14.200 MHz  signal in USB mode into the antenna at +95dbmicroVolt and adjust F07 to  read S9+60dB.

Satellite Operations

Although the FT100 is not designed for use with satellites, several owners have reported moderate success in working satellites with it, namely AO27, RS13, FO20/29,  SO35, UO14 and even AO10.  To work a satellite, the rig must be put in split mode with the uplink and downlink frequencies set appropriately.  If you want to store a satellite settings in memory, you can use the DUP memories which are specifically designed to hold split frequencies.   Working a linear transponder satellite in half duplex mode is not easy.  You should have some experience in using satellites with rigs that have been designed for satellite operations such as the FT847.  

FT100-SuperControl now offers a special satellite mode, that can automatically correct the transceiver with Doppler shift data. The program supports the NOVA and Satscape satellite tracking programs which are used to get the needed range rate data of the desired satellites. Both transceivers VFOs can be automatically updated with the Doppler corrected frequency. And if this is not enough, there is a possibility to turn on additional realtime VFOs which can display the final frequency for optional transverter devices. Of course these final frequencies can also be used for the Doppler shift calculation, so it would be perfect for AO-40.

Separation kit (YSK100)

The separation kit is intended to allow the display/user interface portion of the radio to be physically separated from the chassis of the radio to facilitate installation in confined spaces.  There are three cables included with the kit.  One cable connects the front panel of the radio to the radio chassis.  Another cable is an extension for the microphone and the third is an extension for the external speaker.  There is a convenience to having three separate cables because it gives you more flexibility in mounting the display, microphone, and external speaker.  There is also a plastic bracket to hold the display.  It has a quick release feature similar to the radio chassis, but is not as convenient to use because the latch is harder to reach and to actuate.  The price of the kit is US$79.95.

Some people have broken the latch on the separation kit. If you have this issue and want to see how you might fix it, I wrote a blog entry on how I fabricated a sheet metal replacement latch.

Serial Numbers

Yaesu appears to use the following format for serial numbers on their amateur products:

Year of manufacture-Month of manufacture-Production Run-Individual Unit number

Example: 9D051234 = 1999, February (second month, or "D"), Production Run 05, unit #1234 in this run.

(Apparently Yaesu does not use the letters A or B as a letter in the second position, hence the first month, January, would be a 'C', February is a 'D', etc..)

Some members have reported that they are receiving models beginning with 9D at late as February, 2000 while others are getting units with serial numbers beginning with 9I.  It is unlikely that the 9D units are factory refurbished but rather units that had been accumulating waiting to be updated to the latest revision level and sold as new.  Refurbished products are required by law to be marked as such.

Sidetone/Beep Volume Adjustment

The sidetone/beep volume can be adjusted using VR1004 (labeled VR04 on the board). It is located under the top cover adjacent to the speaker connection. Be very careful as this pot is very small and can easily be damaged.

Storing memories remotely

There are no programs currently available to store the FT100 memory settings remotely because Yaesu did not leave any provisions in the rig for uploading or downloading memory locations. There was a rumor that RT systems was working on a version of ADMS software to provide this capability but they have confirmed that this is not true.   The FT100 has more than 300 memory locations and if you intend to fill them all up, be aware if you ever reset the radio, they will be lost.

There are also no provisions for labeling the memory locations with alpha-numeric labels, most likely because the main display uses 7-segment characters for the main frequency which are only appropriate for displaying numbers, not alpha characters.

It's probably best to think of the FT100 as a mobile HF rig with UHF/VHF capabilities.  It can't compete with all the features you would find on a radio designed specifically for VHF/UHF operation.

SWR meter interpretation

There is no mention in the FT100 manual how to interpret the SWR bar graph on the FT100 display. The following measurements were made on the 10M band by moving the antenna very carefully to get the appropriate number of SWR bars on the FT100 and then disconnecting the radio and measuring the SWR of the ATAS100 with an MFJ259 SWR Analyzer.  The HighSWR icon came on when an SWR with 7 or 8 bars was showing.

Number of FT-100

















UP/DOWN band switching

The UP/DOWN keys are intended to move up and down through the amateur bands according to the manual.  However, several users have noticed that the radio will put additional non-amateur bands in the list if the radio is tuned to them while operating in VFO mode.   Examples of non-amateur bands that can end up in the list include the NOAA weather station (165 MHz), and Citizen's Band (27 MHz).   The FT100 will insert one extra band on the HF side and one on the VHF/UHF side of the radio.   It is not clear how one removes the non-amateur bands from the list other than resetting the radio.

Unsubscribing from the FT100 Yahoo Groups list

Are you tired of getting too much email from the list?  There are now several choices.  You can subscribe to the digest which compiles a single email of all the daily activity on the list and sends you a single email to read instead of one for each subject. This makes it harder to respond to a single subject because you have to edit the subject line and a large portion of the body of the message, but might be more convenient if you spend most of your time reading rather than posting to the list. Also, if you go on vacation and don't want to wade through a pile of email when you return, you can suspend the email for as long as you like and still be able to read it from the Yahoo Groups FT100 web page.  You can still post questions, see responses, access files, and search the archives.  Go to http://groups.yahoo.com/neo/groups/FT100/conversations/messages to see how to do this.

If you really want to quit, just follow these instructions:

You can unsubscribe from the FT100 list by sending an email containing the message:


from the email address where you receive the messages.  The word UNSUBSCRIBE  is all you need to have as the body of the message.  There is no need to have a subject line.

Send it to:


PLEASE NOTE: THE ADDRESS SHOWN ABOVE IS NOT THE SAME AS THE MAILING LIST ADDRESS which is FT100@yahoogroups.com.   Sending an unsubscribe request to the mailing list address does nothing except forward it all to all recipients.

Yaesu Contacts

Attention:  Here is the new contact information for Yaesu:

10900 Walker Street
Cypress, CA 90630
Phone: 714-827-7600
Fax: 714-827-8100

Amateur Sales: amateursales@vxstdusa.com
Amateur Tech Support: amateurtech@vxstdusa.com
Amateur Customer Service: customerservice@vxstdusa.com
Parts: yaesuparts@vxstdusa.com

International contact information can be found at: 


I would like to thank Jay Rutherford, K1UC, for permission to use those portions of the FT847 FAQ which are common to both radios.

If you would like to contribute to the FAQ or have any suggestions, please send them to me at: lee810@yahoo.com.

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