Frequency Expansion Information
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
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| Before MOD |
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| After MOD |
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 above for location details.
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.
Its a poor secret now and I am sure the mod was never as confidential as this doc suggests. Do remember to save all your settings as you need a full hard reset to implement the change.
MODEL: FT-991 - DATE: 23 July 2014
ORIGINAL TX FREQ. RANGE: 160-6M AMATEUR BANDS
NEW TX FREQ. RANGE: 1.8 – 30, 50-54 MHZ
Yaesu FT-991(A) Users Group (groups.io)
https://groups.io/g/Yaesu-FT-991
Yes - I have just discovered and applied the MARS wideband mod. Needs a delicate steady hand and some very thin wire to bridge the jumper blobs. All FB now and happy on 60m (CW too!) I even (just) remembered to save the rig settings using FTRestore beforehand so made recovery from the full reset very easy!
ReplyDeletePosted by: bhardy1755@yahoo.com