[BC] Type acceptance

[Mark Humphrey]

I should also mention that it's sometimes necessary to operate a
transmitter outside the FCC-approved power range, in which case you
can take measurements to show compliance with the emission limits.  I
ran into this problem 20-some years ago at WRTI, where we found it
necessary to operate at BE FM-10A at only 2.5 kW, below its FCC
verified lower limit of 4.5 kW.

Interesting background:  We originally purchased the BE 10 kW
transmitter to replace problematic Wilkinson serial number 001 at an
old site leased from WFLN.    A couple of years later, we applied to
move to the much taller "Gross Tower" in Roxboro where I wanted to
install a 3-bay directional panel antenna and reduce ERP.   The former
owner of this site, Bill Gross, liked the station and made us an
attractive deal, but the tower was almost fully loaded at that time.

However, the local Channel 6 (only 1/2 mile away) objected, claiming
that our proposed 3-bay elevation pattern wouldn't match that of their
6-bay superturnstile.  Legally, they had the upper hand and
negotiations proved fruitless.  Because of the limited structural
capacity, I couldn't add more panels, so was forced to use a
side-mounted 6-bay directional with custom interbay spacing.  This had
three times more power gain than I had bargained for, so we had to cut
the TPO way down.   I suppose we saved some money on the power bills,
but we suffered some major coverage problems.  Athough the side-mount
worked well to the east, our signal on the western back side of the
10-foot face tower was unsatisfactory beyond a few miles.

But several years ago, my successor at WRTI, Jeff DePolo, was able to
secure space atop the "candelabra" of American Tower's new DTV tower,
then obtained FCC approval for the move and recently installed an ERI
4-around panel below one of the TV antennas.  This finally made it
possible to fill the minor lobe to the west between the two
protections at 230 and 335 degrees.   ERI spent a lot of time on this
project, but It's doing a great job to the west now -- I measured an
improvement of 23 dB at 290 degrees.   With 7.7 kW at 435 m (1,427 ft)
AMSL, it's the highest FM radiation center in the market, which helps
in the hilly terrain.

Here a link to WRTI's DA test report, an example of what can be done
with panels, phasing, reflectors -- and plenty of range time.

https://licensing.fcc.gov/cdbs/CDBS_Attachment/getattachment.jsp?appn=101400749&qnum=5070&copynum=1&exhcnum=1

Mark

On Wed, Nov 17, 2010 at 10:36 PM, Harold Hallikainen
<harold at hallikainen.com> wrote:

> Transmitters are now subject to verification.
> http://www.hallikainen.com/FccRules/2011/73/1660/
>
> They may be modified:
>
>   (b) A permittee or licensee planning to modify a transmitter which has
>   been approved by the FCC or verified for compliance must follow the
>   requirements contained in § 73.1690.
>