GMRS operates up in the 450MHz range, CB is 27MHz. The two will not talk to one another. FRS operates on most of the same frequencies as GMRS, just at lower power levels (also, FRS cannot use repeaters like GMRS).
Shoeter, can you be more specific on what you mean by "HAM"? If you mean the ubiquitous "2-meter", that's around 155MHz, and also not "inter-operable" with CB (in "HAM" terms, CB's 27MHz is in the "11 meter" band).
It's like they say - "use the right tool for the job". Sometimes FRS/GMRS is the right tool, sometimes it's CBs, sometimes it's Ham. I noticed recently that CB cuts through foliage (leaves) easier than the higher-frequency FRS/GMRS, for example.
VSWR tuning of the antenna/radio is very important, as Tim mentions - websites such as Walcott Radio have good instructions on how to do this, it isn'
are nCan you tell us a little more about the two other radios in your test? where they were in relation to you at the time, how far away?
