SWR Meters

I am assuming that you are talking about a cheap SWR sold by CB. Shops Highly unlikely. The the AM CB would be 27 megs and UHF is 432 megs. If it is a highly sophisticated unit owned by a wealthy ham operator there may be a chance. It is a frequency problem, not AM -versus FM.
BarryG

Definately not Dave , the am cb SWR meter is a tuned device and will not work correctly.

If you want to get a very rough idea , transmit into a load e.g. 50 ohm resistor or car tail light globe across the coax end, and if your CB has a level meter on transmit , then a lower reading usually means better SWR.

Yeah thank's guys, I didn't think it would but thought I'd ask anyway. It's only a cheap one from Tandys.
Cheers Dave