1460 WXBR For Sale

[4CX1000A]

If it were nondirectional, it might be worth taking a chance. You can always get back on the air with one of those Valcom whips. But I don't think those are allowed in directional arrays, and even a two-tower array needs quite a bit more land than a single tower.

Valcom whips? Sounds kind of kinky!

http://www.valcom-guelph.com/products/V-33085AM-CL2.html

 

[DanStrassberg]

I know of 2 stations using the Valcom: Alex Langer's WFYL 1180 in King of Prussa, and WGCH 1490. WFYL gets out well considering the shortness of the whip(a 94-footer)at 1180. I've heard WGCH on my travels back to New England; it, too, seems to do well with its whip on 1490.

Valcom whips are a lot taller electrically than their physical height would make you suspect. First off, as I understand it, the Fibreglass structure has a high dielectric constant, so it acts as a distributed capacitance from the antenna to ground, which lowers the velocity of propagation, and thus increases the antenna's electrical length. In addition, as I understand it, the main conductor is helically wound on the Fibreglass core, thus forming a distributed inductance and further lowering the propagation velocity, thereby further increasing the electrical height. Then, I believe, there are two lumped L-C networks. One of those I am certain about. It's in the little sphere at the tip of the Fibreglass and it constitutes a top load--although I've never seen any figures on the number of degrees this top load adds. I believe there is also a center load--midway up the Fibreglass, although I'm not sure about that one. Anyhow, WFYL's 94 footer is operating at the lowest frequency the FCC allows for a Valcom whip. The reported efficiency at 1180 is the Class D minimum of 281.7 mV/m/kW @ 1 km. With a standard series-fed tower, that efficiency requires an antenna whose height is 54 electrical degrees or 125' at 1180. So the Valcom technology allows the use of an antenna ~75% of the height of an antenna of standard construction to obtain equal efficiency. Of course, achieving that efficiency requires a standard ground system of 120 1/4-wavelength radials. I suspect that it couldn't hurt to add a 40'-square ground screen at the tower base, as is often done with AM radiators. Perhaps the ground screen would help to compensate for errors that I've heard exist in the FCC curve of efficiency vs electrical height. Supposedly, the FCC curve overstates the efficiency of short antennas--those that are shorter than 75 degrees or so.

 

[WLYNWAZNgm]

1470 WAZN

WAZN was using a whip like this, mounted on a trailer, atop
a hill, next to a water tower, in the Marlboro area. This was
right after MRBI bought the station, before the city of
license was changed to Watertown, and before we built out
the current site in Lexington. It was a temporary
situation - previous owner, Alex Langer, had been forced to vacate his
tower site.