kd4e wrote: > Anyone familiar with NBFM Packet activity on 10M, > 29,100 - 29,300MHz ? > > I came upon an old Sonar VFX 680 NBFM/CW exciter > that covers 160-2M and it got me wondering why > NBFM is not included across the Ham HF spectrum > bandplan. I don't believe it is any wider than > an AM signal.
It all depends on what you mean by narrow-band. Historically, Narrow-band FM was 5 kHz deviation rather than the 15 kHz that was used on the old 60-kc spaced rigs. More recently, they're 'narrow-banding' FM to 2.5 kHz deviation. The newer definition would be legal under FCC part 97 - the restriction which used to say 'no wider than AM' now says No angle-modulated emission may have a modulation index greater than 1 at the highest modulation frequency. So the 'new' definition of 'narrow-band' would fit. ... but older equipment would be using the 'old' definition... a roughly 15 kHz wide signal. Note that the restriction on bandwidth is only for frequencies below 29.0 MHz. 5 kHz deviation *IS* legal above 29.0. And, for those not in the USA -- the regs are probably totally different. > Collins Model 75A-1 is an AM/CW/NBFM receiver from > 1946, so NBFM would appear to have once been permitted. > My TS-430S also supports NBFM... and I use it on 10 meters :) Collins may also have had in mind using it with a VHF converter.
