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The Future of Ancient Modulation Towers

DrAkbar

DrAkbar

Here's KPHX's new two tower site: https://licensing.fcc.gov/cdbs/CDBS...?appn=101800808&qnum=5150&copynum=1&exhcnum=2

The tall stick belongs to KSUN and radiates both 14~Hundred and 14~Eighty. The drop wire radiates 14~Eighty only. As more and more tower sites are being sold for the value of the land, Nurse Jeff and I think we'll be seeing more long wire antennas drop from the guy wires holding up a "real" tower. KPHX will be running with 950 watts day, and 320 watts night. Same pattern day & night.
 
I am picturing where this will all end up. Two huge towers with a guy wire between them and the AM longwires from all the AM stations drooping down :)
 
K6JHU said:
I am picturing where this will all end up. Two huge towers with a guy wire between them and the AM longwires from all the AM stations drooping down :)
Click to expand...

When you see a wire dropping from a guy, it is usually being used to directionalize the signal, actively or passively.

If more than one station wants to use a site, the general procedure is to diplex, triplex or more signals into each tower, with pass and rejection networks for the station frequency and the stations that share the tower.

In general, single wires make poor radiators as there are bandwidth advantages in towers that have a wider cross-section.

When I have seen a permanent vertical wire (hung between two buildings in South America), it was a "cage" of wires forming a hexagram with a fiberglass spacer. It gave a cross section of about 40 cm on each side, and actually sounded quite good. The support "wire" was actually a Phillystran cable that was non-conductive so as to not directionalize the signal.

Shared antennas via diplexing can even work with directional systems, with different stations using different towers at different current and phase "settings". In LA, KBLA, KHJ and the AM on 1230 all share one site, with two of them being directional and one being non-directional.
 
K6JHU said:
I am picturing where this will all end up. Two huge towers with a guy wire between them and the AM longwires from all the AM stations drooping down :)
Click to expand...

It's coming. A lot of these drop wire diplex installations are going in with greatly reduced power. In the case of KPHX, they were 5kw day and 500 watts night. Land got sold, so they've moved to KSUN's stick with 20% of their old day power and 60% of their night power. Enough juice to retain Class B status. But who the hell cares as the owner has an FM translator paired to 14~Eighty. Though the translator is but a mere 3 watts, it counts more than the AM!
 
1700 WRCR in NY has been dark since 2017 and is now proposing to get back on the air using one of the guy wires of an existing tower as a longwire antenna:

wrcrantenna.jpg
 
It seems to me that KXA Seattle used to get out pretty well with a longwire at 1KW on 770. I think they were using it into the 80s!
 
KXA had the advantage of a low frequency and up in Seattle it was almost a clear channel (WABC and KOB as I recollect).
 
KPHX 1480 will actually have as good or better signal once built out at the KSUN tower site. KSUN has a high efficiency 420 foot tower which will be where most of the new 1480 RF will be sent into. The second drop wire antenna is only to add a small amount of directional pattern to the signal with the same pattern day and night. 1480 was originally a 500 watt non-directional daytimer. It installed a two tower directional daytime pattern just to get 5,000 watts bragging rights some years ago, but the pattern was pointed Southwest to obtain the 5KW daytime signal, or away from the bulk of the metro population. 1480 is protecting 1490 in Prescott. With the move a little further east and south at the KSUN site the daytime 2 mv/m contour will cover more population with the proposed 950 watts daytime than in did with the 5 KW signal from the former site. The 320 watt night signal will also cover more population within the Nighttime Interference Free contour of 5.3 mv/m than the former 500 watt three tower directional point more northerly. New pattern with the high efficiency tower will be more cardioid in shape pointed more east and west to cover the metro better. So the bottom line is should be a decent re-engineering of the 1480. But I guess we will see!
 
TowersRus said:
KPHX 1480 will actually have as good or better signal once built out at the KSUN tower site. KSUN has a high efficiency 420 foot tower which will be where most of the new 1480 RF will be sent into. The second drop wire antenna is only to add a small amount of directional pattern to the signal with the same pattern day and night. 1480 was originally a 500 watt non-directional daytimer. It installed a two tower directional daytime pattern just to get 5,000 watts bragging rights some years ago, but the pattern was pointed Southwest to obtain the 5KW daytime signal, or away from the bulk of the metro population. 1480 is protecting 1490 in Prescott. With the move a little further east and south at the KSUN site the daytime 2 mv/m contour will cover more population with the proposed 950 watts daytime than in did with the 5 KW signal from the former site. The 320 watt night signal will also cover more population within the Nighttime Interference Free contour of 5.3 mv/m than the former 500 watt three tower directional point more northerly. New pattern with the high efficiency tower will be more cardioid in shape pointed more east and west to cover the metro better. So the bottom line is should be a decent re-engineering of the 1480. But I guess we will see!
Click to expand...

2 mV/m is a totally useless contour. The ITU has determined that 15 mV/m is the minimum usable signal in urban areas. The usable signal of KPHX does not cover more people than the old signal did. In fact, it covers significantly fewer.
 
EricStein said:
Station owner and local translator king Vic Michael.
Click to expand...

..and when he gets done with 14~Eighty, he'll probably want to upgrade or swap out his 3 watt translator. Just wonder if KPHX will continue to run programming from one of his stations in E Bumphuc, Somewhere?
 
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