[BC] Assistance with a tall tower

[Miltron]

First, I would like to object to the use of the word BRIDGE as used here; it already has a meaning in electrical work: to PARALLEL (usually with the connotation that it is for the purpose of sampling).

But on to your question: 
Wellllll, what does the license show as the R and X of the tower ?
A Pi network is somewhat superior,--but you need to have a way to make the shunt elements variable,--which you usually don't, so T networks are more common. If you're on a lower frequency with a 2F station in the area, it may take a Pi network to get the 2nd harmonic down sufficiently.
This station sounds like a Brer' Rabbit special: a tar baby and maybe a hornet's nest, too...............
M

-----Original Message-----
>From: donroden at hiwaay.net

>1240Khz on a guyed 310 foot tall / two foot face triangular tower.
>
>Any "guestimate" on the series feed R and j ?
>
>It's an old install ..... doesn't look like the conventional "T"  
>network for matching.... More like a "pi-net" with a shunt cap at the  
>coax input to ground. There are two series caps at the antenna input (  
>presumably to bring a high value of +j down to a usable level ? ) a  
>series coil 7 turns 6 inches dia
>and then a homemade self supporting #12 wire coil to another cap to  
>ground at the junction of the "pi" coil and the two series antenna caps.
>
>I can't read the values on the caps .... too weathered.
>
>I can bridge the caps this weekend and measure the reactances, but any  
>advance ball park ideas would be most helpful.
>
>Is a T or a Pi the best network for a tall tower ?
>
>Obviously, it's worked for maybe ten or more years .
>
>Something ( capacitor / coax / insulator ) is breaking down and  
>causing the transmitter swr circuit to foldback. then the fault will  
>clear and return to normal ( normal ... HAHAH ) state until the next  
>audio peak.
>
>This is one of those "tar-babies" that I find myself in occasionally  
>when I do something like getting the transmitter back to full power.
>
>Don Roden
>