Hello to everyone....I asked Kent, WA5VJB, how the 902 / 903 split
ocurred. He told me that long ago, the East got a bunch of crystals
that put them on 903, while the center of the country got a bunch of
crystals that put them on 902. He did not say where the crystals came
from.....surplus, military, obsolete Motorola gear....who knows. How
the West coast got on 903, I don't know.
Many people have noticed that the noise floor is much lower on 902.1
than it is on 903.1. I don't remember who told me this, but his take
was that the manufacturers of all the baby monitors, cordless phones,
and other such "rabbits" were very careful to stay away from the band
edges to avoid being heavily fined by the FCC for out of band
operation. The frequency stability of those kinds of devices is pretty
poor. Hence, the manufacturers have implemented an informal "guard
band"....In other words, they don't make anything that transmits
anywhere near 902Mhz.
Here, 902.1 is pretty quiet, but 903.1 is competely covered with digital
interference that looks like a comb on the scope. It is loud and would
make 903 completely unusable.
If the above is true, then we need to migrate the entire country to
902.1Mhz to avoid all the crap radiators that start at 903 and go up.
However, getting a large area to change will probably never happen,
unless the guys in that area are driven off 903 by the digital "gunk".
However, I have noticed that the really serious stations in the East and
NE tend to have 902 AND 903, since a big tropo opening will definitely
extend into the 902 area of the country.
I want to second the opinion of whoever said that 902 was almost as good
as 423. We can work rovers out to 200miles easily on 902...sometimes
farther. 1296 at those distances is really a struggle and often times,
we just can't make a contact at all when the rovers that are out a bit.
These are my observations....your mileage may vary....73's to all
...Marshall K5QE
Rogers, Ron wrote:
>Unfortunately Dexter, the entire 902-927 Mhz band is an ISM band and we
>amateurs must share it (and put up with) with all sorts of 900 MHZ
>consumer and commercial devices such as cordless phones, cordless
>intercom systems (order takers at the fast food places), walkie-talkies,
>wireless utility meter transmitters, security video/audio systems,
>wireless LAN components, etc. that have now populated the band.
>
>
>Ron
>WW8RR
>
>
>-----Original Message-----
>From: vhfcontesting-bounces@contesting.com
>[mailto:vhfcontesting-bounces@contesting.com] On Behalf Of Dexter
>McIntyre W4DEX
>Sent: Friday, August 08, 2008 10:40 AM
>To: VHF Contesting email
>Subject: Re: [VHFcontesting] [VHF] 902.010 for contests?
>
>Zack Widup wrote:
>
>
>>902 is a lot quieter. I notice the noise floor to be a lot less on 902
>>
>>
>
>
>
>>as compared to 903.
>>
>>
>>
>>
>Zack,
>
>I bought a LO crystal to make the change to 902 several years ago but
>haven't done so yet. I use a DEMI xverter with a FT-221 IF and the IF
>radio will not tune down to 143.100 MHz. However I have patched the
>xverter IF output into a FT-817 I recently bought used which has no TX
>output. Since it will tune 143 MHz I have listened on 902.100 just to
>see how the noise was. At my QTH the noise floor is the same as at 903
>but what I do hear right on 903.100 is a continuous FM signal on which I
>often hear something like "I'll take chicken nuggets and a Pepsi" Are
>fast food joints allowed to use this frequency?
>
>W4DEX
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>
>
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