Live aprs.fi

Sunday, March 1, 2015

FT-991 Expand TX ( MARS Modification )



This brand new radio was sent to me to do the MARS modification. With this modification, the radio could go on air from 1.8MHz to 30MHz and 50MHz to 54MHz. Before the modification, I'd test on VHF and UHF, seems the radio could TX from 136MHz to 174MHz and 420MHz to 470MHz without any modification. So the MARS modification only affect on 160 and 6 meter band.

A quick 'Google' bringing me to this blog. After understand what am I dealing with, I strip off the new radio. According to the article, it's quite easy access. huh! But after removing the bottom cover, I could not locate the CNTL-UNIT. 

Bottom cover removed, but where is CNTL-UNIT?


Then I remove the top cover as well, and the front panel. After peeking for a while, finally I located the CNTL-UNIT. It's between the front panel and body. I never thought is was there.

Top cover removed, you may left the handle, unscrew it few turns

Top cover out

Gently pry out the front panel 
Gently pull out the small ribbon cable, the big ribbon cable you need to unlock the connector.
My advice is to remove the small ribbon cable here.

Pull out the connector. You may remove the big ribbon here , but not the small ribbon, I find it hard to put it back.
The CNTL -UNIT, remove the rubber.

Unscrew it
Factory setting
New jumper soldered!
Label it!

Re-assemble

Re-assemble everything back, and do a hard CPU reset. 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.
1.8MHz to 30MHz TX 

FT-991 you're good to go!