Yaesu FT-991 Frequency Expansion Information


Model: FT-991
Original TX Freq. Range: 160-6m Amateur Bands
New TX Freq. Range: 1.8 – 30, 50-54 MHz

This information is solely for use by licensed members of MARS (Military Affiliate Radio System) or CAP (Civil Air Patrol), and release to any other party is not authorized. Use of any Amateur Radio product outside of the Amateur band is at the users own risk, and no guarantee of compliance with specifications outside the Amateur bands is expressed or implied. The Limited Warranty does not cover damage caused by any attempt to modify an apparatus for out-of-Amateur-band operation, nor does the Limited Warranty cover damage to components that may result from out-of-Amateur-band use.
Modification Procedure:
Remove the bottom cover. On the CNTL-UNIT, place a solder bridge across the pads at JP3003, expanded transmission will be engaged. See the images below for location details.

: FT-991_MARS_Mod

Make a note of all your Menu settings, so you can re-load them quickly, then do a hard CPU reset in order to save the new frequency range. To do this, turn the transceiver off, then press and hold in the [FAST] and [LOCK] keys; hold them in while turning the radio back on. When the radio comes on, you may release these two keys.

FT-991 Expand TX ( MARS Modification )


Yaesu FT-991(A) Users Group (groups.io)

1 comment:

  1. Anonymous9/09/2016

    I purchased my FT-991 form Ham Radio Outlet in July of 2016. As of today September 4, 2016, I have not experienced anything unusual. One of the reasons I purchased this radio was to take on long road trips in the U.S. Our trips are usually 1500 miles one way. I did the MARS / CAP mod on my radio and every thing is great. Being just a Technician Class Operator, I am limited on voice frequencies (10 meter). However, after the mod, I am able to listen to 11 meter (CB) as well. I went to a great deal of trouble to install a Wilson 1000 antenna on our Lincoln MKX (the roof is all glass due to the oversized sun roof). This is my 1st HF radio and without much effort I was able to understand the basic operations of the radio. The Wilson 1000 is of course designed for CB but with the assistance of the internal ATU I am able to talk on 10 meter without issue and has low SWR. Our last trip brought us close to Atlanta, GA so we went by HRO and purchased a HEIL headset w/ boom mic. The headset is also working fine. I don't have an HF antenna at my QTH yet. I'm still debating on just using the Wilson 1000 mounted on my VHF/UHF mast or a G5RV or some variety of vertical.


Comments may take a day to show up

Yaesu FT-991(A) Users Group (groups.io)