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Class C FM spacing (exception?)

R

rye

Guest
I have been studying FM spacing rules and came across a situation i can't figure out.

The FCC spacing rules state that a Class C FM must be 105 kilometers away from a second-adjacent Class C. In Austin, Texas there is KLBJ-FM (Class C) 93.7 with a tower in town and KDHT-FM (Class C) 93.3 with a tower northwest of town. The distance between the two sites is only 49.93 kilometers.

Anybody know how this could be?

Rye
 
> I have been studying FM spacing rules and came across a
> situation i can't figure out.
>
> The FCC spacing rules state that a Class C FM must be 105
> kilometers away from a second-adjacent Class C. In Austin,
> Texas there is KLBJ-FM (Class C) 93.7 with a tower in town
> and KDHT-FM (Class C) 93.3 with a tower northwest of town.
> The distance between the two sites is only 49.93 kilometers.
>
>
> Anybody know how this could be?
>
> Rye
>

Because KDHT-FM was on the air before 1964, the allocation falls under the pre-1964 spacing rules (commonly called "Grandfather Spacing"). Under those rules, the allocation can be short-spaced to KLBJ-FM. I don't have the old spacing info with me, but generally it requires much less space between first and second adjacent stations.<P ID="signature">______________
</P>
 
Prior to 1964, there was no table of minimum separations. Allocation was done by contour overlap, with not much protection to second adjacent channels (the 80 mv couldn't overlap the 1 mv, I believe). This was latter codified by a separate sectionof the rules, again allowing considerable latititude for both power increases and site locations by these grandfathered stations to each other.
 
> Prior to 1964, there was no table of minimum separations.
> Allocation was done by contour overlap, with not much
> protection to second adjacent channels (the 80 mv couldn't
> overlap the 1 mv, I believe). This was latter codified by a
> separate sectionof the rules, again allowing considerable
> latititude for both power increases and site locations by
> these grandfathered stations to each other.
>

Thanks for the great info, I knew the spacing was different, I didn't realize that they didn't do it by mileage, though. I learned something new!<P ID="signature">______________
</P>
 
Re: Grandfathering doesn't apply in this case...

KDHT 93.3 in its present incarnation as a full-power Class C FM wasn't around back in 1964. Then called KLEN-FM, it was what amounted to a Class A, running just 760 watts from a short tower and it basically served just the town of Killeen. In the 1970's they increased their power and antenna height somewhat, but the big increase to 100,000 watts and the move to the tower between Bertram and Liberty Hill, about 35 miles northwest of Austin, came in the mid 80's.

As for how it happened that 93.3 was able to move to a site that's around 30 miles short-spaced to KLBJ 93.7, there are conflicting stories. Some have speculated that the Johnson family pulled some strings in Washington and received a rather handsome sum from the owners of the Killeen station.
 
Re: Grandfathering doesn't apply in this case...

> KDHT 93.3 in its present incarnation as a full-power Class C
> FM wasn't around back in 1964. Then called KLEN-FM, it was
> what amounted to a Class A, running just 760 watts from a
> short tower and it basically served just the town of
> Killeen. In the 1970's they increased their power and
> antenna height somewhat, but the big increase to 100,000
> watts and the move to the tower between Bertram and Liberty
> Hill, about 35 miles northwest of Austin, came in the mid
> 80's.
>
> As for how it happened that 93.3 was able to move to a site
> that's around 30 miles short-spaced to KLBJ 93.7, there are
> conflicting stories. Some have speculated that the Johnson
> family pulled some strings in Washington and received a
> rather handsome sum from the owners of the Killeen station.
>
It is my understanding the 93.3 and 93.7 were already shortspaced when the 1964 rules came out....in those rules is a clause that allows stations that were shortspaced to remain so and allow upgrades or changes to their max allocation regardless of shortspacing already in place...thus thats how 93.3 was able to get its 2000ft site as a C (they were given a C status under the 64 allocations from what I recall)...it would not make sense for the Johnson family to pull strings for a MOVE in??! and LBJ was long gone by then....The family was on the way out of radio anyway...looking at the recent COL change of 93.3, the 1964 issue is mentioned over and over in the proceeding...and it is a fact that 93.3 was allowed to upgrade under that ruling.
 
Re: Grandfathering doesn't apply in this case...

> It is my understanding the 93.3 and 93.7 were already
> shortspaced when the 1964 rules came out....in those rules
> is a clause that allows stations that were shortspaced to
> remain so and allow upgrades or changes to their max
> allocation regardless of shortspacing already in
> place...thus thats how 93.3 was able to get its 2000ft site
> as a C (they were given a C status under the 64 allocations
> from what I recall)...it would not make sense for the
> Johnson family to pull strings for a MOVE in??! and LBJ was
> long gone by then....The family was on the way out of radio
> anyway...looking at the recent COL change of 93.3, the 1964
> issue is mentioned over and over in the proceeding...and it
> is a fact that 93.3 was allowed to upgrade under that
> ruling.

I've reviewed a number of short spacing situations in the past and in virtually all of them one or both of the stations were allowed to upgrade by increasing their HAAT or ERP in place, meaning neither could move closer to the other. There are two notable cases in Texas: 95.5 Diboll-95.7 Houston and 95.5 Austin/95.5 Waco. In the Austin/Waco situation two co-channel Class C stations were located around 90 miles apart (about half the required distance). Under grandfathering they were actually eligible to have 100kW ERP at 2000 feet, but were not allowed to decrease the distance between them. As it turned out the Waco station switched to 95.7 a few years ago and downgraded to a C2.
 
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