Re: [IRCA] Tower height vs power
Patrick Martin wrote: Thanks Patrick. Interesting, when 620 Portland left the towers in North Portland to be diplexed with KEX 1190 (200'), the coverage dropped quite a bit. CC then applied for 25/10 KW for 620. They now have the best signal of any Portland area station on the coast except for KEX 1190 (50 KW) nights. The strongest day signal is 620 followed closely by 860 KPAM, then KXL 750. Those KEX towers are no 200-footers! They're 455 feet each, which is 102 degrees (0.28 wavelength) at 620 kHz. At 1190, they're 196-degree towers, which is just over half-wave. The KEX towers are big, fat old Blaw-Knoxes, too, which means that they're extremely wide-bandwidth. If not for the IBOC, they'd produce really nice-sounding audio :-) s ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
Re: [IRCA] Tower height vs power
At 11:41 AM 2/3/2007 -0800, you wrote: I have never seen nor heard of any AM Broadcast station -- ever trying to use a full wave length tower. It would be very very difficult to feed. Does anyone know of any AM broadcaster using a full wave tower ??? Mike, Disagree. Standard theory suggests that a full-wave tower would have a rather low impedance, requiring some unusual matching, but nothing insurmountable. Alternative feed method would be to ground the tower and run a feedwire up the side of the tower to a point where the feed impedance would be more typical. In principle, it should be possible to find a point at a fraction of the tower's height where there would be a 52-ohm resistive match exactly. 73 de Charlie - Charles A Taylor, WD4INP Greenville, North Carolina ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
Re: [IRCA] Tower height vs power
I know that the present discussion concerns antenna height in degrees and not actual physical height. A full wave tower, of course, would be 360 degrees tall. And a 5/8 wave would be 225 degrees. But the physical height would depend on the frequency. I thought that some of you might be interested to know that in 2002 I conducted an FCC file search for the physically tallest AM tower in the US. This search included the formula for greatest height in degrees vs lowest frequency. The physically tallest AM tower that I found was a 203.4 degree tower on 560 kHz in Monroe, MI. That would be about 989 feet tall. That was the night tower for WLLZ (now WRDT) with a power of only 14 watts. It is a folded unipole, or a similar derivative, on the side of an existing TV tower. They also have a more conventional 4-tower daytime site at a seperate location. Patrick Griffith, Westminster CO Certified Broadcast Technician KCKK / KJAC / KCUV http://community.webtv.net/N0NNK/ http://community.webtv.net/AM-DXer/ ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
Re: [IRCA] Tower height vs power
Thanks Patrick. Interesting, when 620 Portland left the towers in North Portland to be diplexed with KEX 1190 (200'), the coverage dropped quite a bit. CC then applied for 25/10 KW for 620. They now have the best signal of any Portland area station on the coast except for KEX 1190 (50 KW) nights. The strongest day signal is 620 followed closely by 860 KPAM, then KXL 750. 73, Patrick Patrick Martin KAVT Reception Manager ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
Re: [IRCA] Tower height vs power
Scott, I guess I should have mentioned, I was referring to groundwave instead of skywave. The skip angle would be different. Mentioning tower height, it taller the better was the rule, how much better would a full wave tower work over 1/2 or 5/8 wave? If a 1 KW station is running 1/4 wave, going to a full wave, how much power would the station need to equal the signal they had with 1/4 wave at 1 KW? Thanks. 73, Patrick Patrick Martin KAVT Reception Manager ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
Re: [IRCA] Tower height vs power
Patrick -- As you go higher than a 5/8ths wave -- you start to get a kick-back of skywave against the ground wave. A full wave would be like using a tree stump. Almost all of the Clear Channel -- 1A -- 50 kw stations use half-wave. And you do have to figure the ground as well as the ground system into the total working system. ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
Re: [IRCA] Tower height vs power
Mike, Thanks. I fiqured there must be a reason no one uses anything over 5/8 on a tower. In some areas, I am sure a fullwave tower could be used. 73, Patrick Patrick Martin KAVT Reception Manager ___ IRCA mailing list IRCA@hard-core-dx.com http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: irca@hard-core-dx.com
