"Alex" ) writes:
Hello,

I'm new to amateur radio, and there's a debate amoung some of my
friends on whether it's legal to modify a ham radio to transmit on
commercial and CB frequencies. I thought any radio that does transmit
on these non-ham frequencies needs to have some type of FCC
cerification, so modifying a ham radio to transmit on such non-ham
frequencies would be illegal. However, some friends have told me it is
legal to modify a ham radio to transmit on non-ham frequencies as long
as you are authorized to use them and you transmit on those specific
frequencies and on the allowed power.

At my work we have been allocated to use specific frequencies which are
commercial and not within the ham frequency range, and I thought it
would be illegal to modify a handheld ham radio to transmit on these
frequencies. Am I correct?

If so, can someone point me to a website, whether on the FCC's site or
ARRL's site or someplace else that shows this? Again, I assumed it was
not legal to use a modified ham radio on such non-ham frequencies, but
I've heard from others that it is. Just wanted to clear the air.

Amateur radio is almost unique, in that the rules are intended for
experimentation and thus pretty open. Pretty much all the other radio
services have quite limiting rules, and yes, one of those is about
the radios matching very specific standards.

Hence, no one cannot used modified equipment in another service. Indeed,
modifying a piece of commercial equipment for another service is likely
to make it no longer useful for that service.

What seems like an obvious exception, using ham gear for MARS (and CAP
if that still happens) is misleading. Because both services allow for
amateur equipment to be used on those frequencies, the whole point being
to make use of the existing pool of ham operators. Certainly MARS,
and I think CAP, used frequencies adjacent to the ham bands so it
was easy to use the same equipment. Decades ago, hams often had
receivers that had a bit of extra tuning range that would take
in those adjacent frequencies, and the transmitter could be shifted
simply by changing crystals. This has changed as ham equipment
has changed, so an actual modification is often required to take
in those MARS frequencies. But that is just an opening up of the
coverage.

Of course, modifying the other way works fine. Plenty of CB radios
have been put to use on the ham bands after modification. But noteworthy
is that once that equipment is modified, it's no longer suitable for
its original use, and I believe the rules are such that even putting
things back to normal is not good enough.

Michael VE2BVW