oldtvman2 wrote:capacitors in parallel add and the voltage stays the same. when matching the antenna it dosen't matter how many cap you use what matters is that you have a match. when using several capacitors you have a greater chance of one breaking down. and changing the match. with the antenna matched and the transmitter having the proper output current everything should be ok. if the antenna is not matched then the pattern could be greater or less depending on the match. dc blocking usually isn't a concern at the antenna. in the old days the transmitter engineer knew the values in his tuning unit. but then we had engineers at the transmitter and full time at the station, not contract engineers. bees like tuning units because there is a certain ammount of heat generated and they like that. have had to use a lot of wasp spray when checking base current readings. also their nest can change the tuning of the antenna.
We may have to agree to disagree. The output leg cap(coupling cap) on a standard "T" network often adds capacitance to, in some cases, an already capacitive antenna. Other than to change other component values in the ATU, the cap only functions as a "poor man’s fuse" to the outside world. While I have seen this cap removed on -J towers, I personally would not remove it. Direct lighting strikes can split or explode the coupling caps. I have seen that happen several times with no other damage. An often misconception is the static drain choke and arc gap will do the job. It all boils down to the arc gap and how much will make it through the coupling cap. Static drain chokes are not designed to shunt lighting strikes. Relatively speaking, lightning strikes are more theory than science, but we do know that lighting strikes contain both RF and DC. So I would have to argue that you can get "some" DC blocking and protection from the coupling cap.
the t matching network could also be inductive with the cap to ground in the middle. the static drain is for static electricity that would be generated by the wind.and was usually a small rf choke 2 1/5 mh. the tuning unit is to offset the j factor and to make the antenna look as a restive load to match the feed line from the transmitter. once this is set up it dosen't change except when something blows or is changed, or the ground system was stolen. this happened a lot at WWHY.
Really? I think we lived in a grey(or white) house, 2cd on the right, coming into that lil' strip of civilization. Walked to the old elementary school...sweet little neighborhood. I drove though it maybe 10 or 12 years ago..strange how small it was, considering that as a 4th grader, it seemed immense.
America is at that awkward stage.
It is too late to work within the system,
but too early to shoot the bastards.
- Claire Wolfe