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guess I need some help

 
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guess I need some help
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RadioMan
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Joined: 03 Nov 2003
Posts: 48

Post guess I need some help Reply with quote
HELP....i am having some problems with some stuff.

#1. I live in a major metro area in the states. There are technically NO FM channels open in this market, but I have found a few that are clear at least two channels either up or down, and no stations within 90-100 miles of me on the same freq. I am being blown off air by a full power (10k watts) station about 100 miles from here, but only on cloudy days. It's not the normal range of that station, obviously, and I know that this sometimes happens on FM (more often on AM). I used to get out about 2-2 & 1/2 miles. Now only 1 block or so when they blast in here(3-4 days week). I have checked my gear and everything is within normal paramaters. Any thoughts?

#2. My ideal frequency would be, say, 99.9 for a number of reasons. But, when I operate at that freq., or at 93.9, I cause major interference with neighbors on TV channels 2,4,9, & a couple of UHFs. Not on 6, 7, or 12. When I'm up where I am now, at 107.1 I cause no interference. Thats what I don't understand. Why I would cause interference at 93.9 & 99.9 but not at 107.1 or 107.9 wouldn't?

Here is my set-up:

Max Pro II x-mitter,
Power Supply 14v, 2a.
Antenna is a homemade Slim-Jim that was originally tuned to 93.9. It is mounted to a chimminey only about 25-30 feet above ground level. I have no SWR so I used math to cut the specs for the antenna. Everything is intact as far as coax and connectors are concerned.
(BTW- I found a web site that says they have SWR/feild strength meters for $10-$20 that are for the broadcast band. I am going to order one tomorrow-will let you know what happend. If you care to check out their site they are called "Candy" electronics. Forgot their address so just google it.)
I am figuring my power out to be between 4-5 watts by the indirect method(good old ohms law) from the "power out" test point on exciter..if that is the correct place to mesure E & R.

So...3 questions:
1-can the power out be figure from the "power out" point?
2-why would I cause interference at 93.9 & 99.9 and not on 107.1/.9 when the antenna is tuned to 93.9?
3-Why would a station at 10k watts blow me off from 100 miles away? Why would I go one block when they come in here and get out a mile or two when they don't?

Sorry for going on so long.

Pcs-my power supply delemia was solved by running two of the 14v outputs in parallel. One had only 500ma, the other was about 1.6 amps. I found out the hard way by blowing up my old multimeter.

(BTW- I found a web site that says they have SWR/feild strength meters for $10-$20 that are for the broadcast band. I am going to order one tomorrow-will advise you when I get it. If you care to check out their site they are called "Candy" electronics. Forgot their address so just google it.)
Thu Mar 31, 2005 6:56 pm View user's profile Send private message
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