Just for the sheer devilment of being able to say "told you I could" because someone told me "it's not possible", I've designed and am prototyping a cute little board to add SSB to a 27/81 CB chassis with a ROM locked PLL chip.
(and yes, I know it's it's not legal to use on air 'as is' so it won't be. The next step is to swap out the LC7137 and get it on 10M)
@ClintJayIO83
I wouldn't worry about it. Both of OfCom's enforcement officers are busy using ChatGPT to send vaguely threatening letters to every site on the Internet that displays the colour of human skin.
@jamesb I'm not worried about OFCOM, it's the "ackshually, I think you'll find" and the condemnation of those who ate the rule book, I have to consider my age because there's only so many times I can tell them to ".... off" before I get arthritis in my thumbs. Plus, SSB on those odd .00125 frequencies would be useless
@ClintJayIO83
Block quickly, block early and remember the eternal rule "it's easier to ask forgiveness than permission".
@ClintJayIO83
Or just retune to .555 where's it's lawless and nobody fucking cares.

@ClintJayIO83 Best. Motivation. Ever! Love to hear how it works. This is how progress is often made!

Interesting to hear you say it's not legal.

AFAIK in Australia the rules are that you can modify a type approved radio to use amateur frequencies and modes, but you cannot modify a radio to use type approved frequencies and modes, except in emergency situations.

So you can modify a CB Radio to use say 10m or 70cm, but not a Yaesu 857d to use 11m or UHF CB.

Is that not the case in the UK?

@vk6flab ah, it's not legal to use SSB on the frequencies the ROM locked PLL can create (LC7137 if you want to see where it sits). To move it to 10M where I can use it legally takes a bit more work, for ease I'll change out the PLL to something a little more flexible but that does rely on my not losing interest in it

From what you say, the laws around modified equipment sound very similar here as they are there.