At 10:50 AM 12/25/07, you wrote:
Jim,
I'd be interested to know where in part 97 you find any restriction
on FM below 29.5. (Without debating it, of course.) ARRL bandplan,
yes, but FCC rules?
Keith, we're also stuck with band-planning on other bands which
didn't anticipate the popularity of FM repeaters. 2m is even more
screwed up. Why have only 600 kHz offset, when it could have easily
been double that? Duplexers would have been smaller, less expensive,
worked better, etc.
Pure and simple - hardware issues.
The answer is nobody had figured out in the early 1960s that FM
repeaters would grow to be the dominant mode on the band.
Originally, repeaters used 30 kHz channel spacing with inputs
between 146.0 and 146.4, then a 200 kHz buffer zone for simplex, and
outputs between 146.6 and 147.0. When additional repeater subbands
were added, it would have made sense to go to a 1 MHz split, but at
the time too many repeater ops would have bitched about buying
crystals and retuning duplexers.
I think the users would have bitched more than the repeater ops
(which I read as repeater owners, sorry if I misunderstood).
73,
Paul, AE4KR
Like Paul said, history has a lot to do with it.
I doubt if most of the hams that got started in the 80s or 90s know, but the
initial start for VHF FM was when the FCC mandated the change from
+/- 15KHz dev and 60KHz spacing to +/-5khz and 30KHz spacing.
This dumped tens of thousands of radios onto the amateur marketplace
nationwide in the late 1960s/early 1970s.
The mobiles of the day were a mix of all tube construction and hybrid
construction (tube transmitters and solid state receivers). Both had
receivers that if stagger-tuned would cover about a megahertz to a
megahertz and a half, and the transmitters would do a little more.
So the mobile receivers were put in the middle (centered on 147.00),
and the transmitters straddled them. The receivers managed to hear
from 146.5 to about 147.5 with decent performance, and the transmitters
groaned a little at 146.01 or 147.99
And Wayne Green W2NSD of 73 Magazine deserves a lot of the credit -
he pushed 2m FM heavily, and had two or three articles every month
that were relevant. Yes he was controversial, and a number of people
disagreed with him, but like him or not, without him the hobby wouldn't
be where it is today.
Mike WA6ILQ
