[BC] AM Allocation research

[Mike McCarthy]

Jeff,

Don't forget WPNA, Oak Park--co channel to both as well--  Though WPNA and
WGEZ are now co-owned. It's almost a perfect equilaterial trinagle between
the three of them.

One of my stations is also super short spaced.  WSBC is super short spaced
to a co-channel station in Sterling. What's more there are two sets of
stations on 1230/1240 which have their 5mV contours abut.  Talk about
mutual destruction....

MM

> Hello,
>
> Anyone here know how long the channel allocation rules have been around
> for class C AM stations?
>
> I have done the calculations for existing class C AM stations, and two out
> of the two pairs of existing stations come up short spaced.
>
> I used the FCC web Java script as well as a couple of Great Circle
> programs suggested by the membership here. I'm therefore confident that
> the distances are OK. I also deliberately picked two stations to study
> that have the same ground conductivity as per FCC map in 73.190, so I
> don't have to mess around with an Equivalent Distance calculation since
> the ground conductivity is the same as per the map.
>
> I used actual antenna RMS for the two stations and when that came up close
> spaced, I used the minimum acceptable RMS of 241 mv/m @ 1 km as per the
> FCC rules. I then followed 73.37(b) and assumed both stations putting out
> 250 watts (120.5 mv/m effective field) and still ended up with a short
> spaced situation.
>
> The geographical spacing comes out to 132 km. The required cochannel
> spacing is the radius of the .025 mv/m contour plus the radius of the .5
> mv/m which comes to 154 km required spacing.
>
> I don't recall there ever being a short-spaced situation with AM class C,
> do you? My understanding is that these rules are pretty old.
>
> I'm probably making some silly mistake somewhere :-) BTW, the station
> spacing I'm studying is WGEZ from WZOE on 1490, if you want to follow
> along.
>
> Thanks,
>
> Jeff Glass
> Northern Illinois University