I spoke with a TECH That works for a major Ham Radio Dealer and to not cause him any trouble here is what he had said about the MARS MOD. " I do not recommend doing the Mars modification because if you use this on 11 meters it will damage your finals. " I am glad he was honest with me so I will not have this done. So, I leave it up to all on this forum if you want this done. I have 11-meter radio's so I don't need the mod anyway. MERRY CHRISTMAS AND HAPPY NEW YEAR TO ALL AND MAY GOD BLESS EACH AND EVERYONE FROM THIS OLD MAN
Yaesu: 2022 Yaesu FT 891 MARS MOD
- Thread starter columbas
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Unless someone intends to use just SSB (or FM) there isn't much reason to modify the FT-891 anyway. Its AM design makes for a very poorly modulated signal from the transmitter and there isn't a way to improve on this that I have found. The SSB and FM, however, work quite well. If operated at low power levels, say 15 watts or below, there isn't enough energy flying around in the inappropriately tuned circuits to hurt anything but then the only advantage the radio offers over a CB is it's digital processing for the receiver.
As far as the "mod" itself is concerned, I discovered that a physical modification of the radio isn't necessary at all. The covers need not be removed. This radio can be modified from the front panel to operate anywhere and in any mode desired. It's too bad the AM side of things is so poor on this otherwise fantastic little radio.
As far as the "mod" itself is concerned, I discovered that a physical modification of the radio isn't necessary at all. The covers need not be removed. This radio can be modified from the front panel to operate anywhere and in any mode desired. It's too bad the AM side of things is so poor on this otherwise fantastic little radio.
Interesting, it appears all HF radios made by Yaesu since at least the 80s have been factory designed to work 1.6 to 30MHz continuous where all the low pass filters switch at the right points, the PA is happy, etc. Why would Yaesu make a modern radio that has a factory back door to wide band but it can't actually do the deed? Doesn't make sense.
There are also maybe tens of thousands of 891s out there with a good portion of them MARS modded and I have not heard of any problems. Just stating it will damage the finals is not enough information. Why would they be damaged? Under what conditions? Who is this guy and who knows if he actually knows anything???
There are also maybe tens of thousands of 891s out there with a good portion of them MARS modded and I have not heard of any problems. Just stating it will damage the finals is not enough information. Why would they be damaged? Under what conditions? Who is this guy and who knows if he actually knows anything???
Because it isn't a back door, using it as one is an abuse of this function's intended purpose. Hence the need to reduce power.
mmckenna
I ♥ Ø
Just a point of order:
It's probably using 25KHz wide channels
"CB Radio" FM is 8KHz wide channels.
Using that radio on FM for the CB frequencies is probably going to sound like poop.
522
Active Member
I have never heard of this method. Do you have any info on this?
Like I stated earlier, it is an "abuse" of its intended purpose. In the rare (very rare) need to communicate within 11 meters (or any other frequencies) it works if it is used carefully with low power. I prefer not to go into details.
I don’t know if the tech I spoke of is the only one that works for the company If I told the company name it might get back to that company and get him fired. I quoted the text he sent me and I have no other information other than the quote I gave everyone. Sorry I don’t more information to give. I don’t know if the year made has anything to do with what he advised or not. Buy my ft 891 is a 2022 model.
522
Active Member
Oh brother
There has to be thousands and thousands of 891s being used out of band and if it was actually a problem we would have heard about all the failures. I'm not finding any, does anyone know of a failure using an 891 on CB?
522
Active Member
No problems here ... however, for 11 Meters I only use 38LSB ... but regardless, no issues.
ryanhuggins
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without looking at the spec sheet, the final transistors would be rated for at minimum 1.8-30 MHz, possibly up to 54 MHz depending on the design. If there were mismatched resonant filters, there could be some degradation, but considering there is an amateur band that ends at 24.890 and one that starts at 28.000, id bet dollars to donuts it would work in spec on 26/27 MHz as well.
The PA is a broadband device. As long as the correct lowpass filter is switched in and you don't abuse it with extreme SWRs, the finals will be perfectly happy on 11m.
The FT-891 can do NBFM with +/- 2.5kHz deviation. The modulation index is <=1 and the FM bandwidth is therefore approximately 2 x AF bandwidth which means the radio could be, in the technical but not legal sense, used for CB radio.
mmckenna
I ♥ Ø
Nice to hear more and more ham manufacturers are embracing FM narrow band.
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