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Post by Deleted on Aug 19, 2017 14:40:57 GMT
KDX-FM Transmitter Move
KDX-FM transmits from a Ramsey FM30b transmitter which until yesterday shared space on an indoor bamboo tripod tower located about 4-feet behind the operator position in the master control room.
The bamboo tripod currently hangs the receiving antenna for the station's Lectronics Wireless Mocrophone.
The new KDX-FM transmitter location shares an audio line from the SSTran AMT3000 KDX-AM transmitter alongside the legendary "Wintenna", a metal window frame serving as a portion of a 3-meter vertical antenna facing in and out doors.
The KDX-FM telescopic vertical antenna is about 15-feet from the control area and because of the adjacent window is expected to better serve a portion of the campus outside the building.
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Post by Deleted on Aug 20, 2017 17:29:30 GMT
First Range Test
The LCD display for the RF Power shows black bars that become visible or invisible as the power is turned up or down.
In the late afternoon I set the first black bar for visible and backed down the driveway. The signal was almost immediately overcome by spotty reception from a religious translator many miles away.
Beyond the driveway riding on the street I had no signal at all.
Strange because when the same FM transmitter was located in the center of the building the street reception was still usable.
The next time we go out we will try full power.
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Post by thelegacy on Aug 20, 2017 18:12:04 GMT
You are obviously experiencing signal absorbs-ion from trees, even if you have an antenna 10 feet away from your transmitter it will effect FM in ways it won't effect AM. so I suggest you get your TX as high as possible and no metal objects anywhere near it.
Some folks with Ramseys have used outside antennas and even at low power 1mW to 25 mW if done right could get you out an entire neighborhood. Also many folks transmitting considerably HIGHER POWER have this same issue when it comes to objects close to your antenna. It even effects your SWR as well.
Radio Brandy is selling a modified Workman SWR-3P meter that covers lower power levels than 1 Watt for FM so you can actually see what your SWR is. The lower your SWR even at P15 levels the better your range is. Your signal will also be more stable.
This is why I always have said under the correct conditions you can go further than 200 Ft legally but it requires homework. Good Luck with your FM project.
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Post by thelegacy on Aug 20, 2017 18:14:00 GMT
Oh another thing before I forget if you hear a station that has a translator on your frequency I know you don't want your signal going past your property line. Good way to get an FCC complaint. Just food for thought.
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Post by Deleted on Aug 20, 2017 19:13:14 GMT
New Period of Development
Thanks for your good input TheLegacy.
I'm going to investigate whether the translator on my channel is legal, as previously I was in the exact triangular fringe of three college stations. The translator is gospel music rubbish.
Also I'll look into that new RF device from Radio Brandy.
Your comments about antenna placement are correct and I agree with them.
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Post by Deleted on Aug 20, 2017 19:41:07 GMT
Found the Culprit
The station that pops in from time to time is licensed for 68 Watts and I am in their fringe area.
They are never received from inside the building and there are no FM listeners in my driveway (except me).
I know we "Must accept interference" but this gospel music is so terrible it is worse than interference. Ironically it is a hellish sound.
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Post by Deleted on Sept 10, 2017 19:59:45 GMT
EDM Transmitter in Service
For KDX this is a time of FM development.
The previous use of FM as a studio-to-transmitter link has been discontinued.
As of this past week FM is the official monitoring medium at our control desk, where we have the on air signal and a production channel on two different frequencies.
Based on Tim in Bovey's inspiring EDM Transmitter Review at part15_us we have ordered the same model he talked about, EDM-LCD-CS-EP.
We have taken an interest in using all horizontal dipole antennas for FM transmission.
It is appealing to us that the signal can be aimed directionally in two opposing directions and the side lobes being nulled out, which will focus the signals on the length of our campus while casting little signal toward neighboring buildings.
First problem with horizontal is physical structure and placement. Unlike a simple whip standing vertically, a horizontal wire or metal piece must be held firm along it's length.
It seems reasonable that a horizontally polarized signal will perform better indoors, where room sizes are wider and longer than floor-to-ceiling ratios. This has not been proven or mentioned elsewhere, but we will believe it until we know otherwise.
All comments on these thoughts will be much appreciated.
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Post by Deleted on Sept 10, 2017 22:22:39 GMT
With a horizontal dipole, you'll lose a great deal of signal on the receiving end unless that antenna is correctly polarized (i.e., horizontal as well).
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Post by Deleted on Sept 10, 2017 23:07:51 GMT
Taken Into Account
DavidC: "With a horizontal dipole, you'll lose a great deal of signal on the receiving end unless that antenna is correctly polarized (i.e., horizontal as well)."
Luckily all applicable receivers are capable of having their whips rotated into horizontal position.
In some cases that might pose the problem of having antennas sticking into inconvenient locations. Another design problem.
If I find that horizontal is not provably better than vertical in an indoor environment, it will be vertical from then on.
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Post by thelegacy on Sept 11, 2017 1:50:12 GMT
What about citcompolar antennas or folded dipole antenna for indoor flycasting or yard casting at 11 nanowatts?
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Post by Deleted on Sept 11, 2017 2:51:22 GMT
Antenna Choices
TheLegacy suggests: "What about citcompolar antennas or folded dipole antenna for indoor flycasting or yard casting at 11 nanowatts?"
Don't we wish.
I have never had experience with anything other than straight wires and whips.
Got to build or buy some curvy multi-polar antennas for test purposes.
As DavidC mentioned, we may want to put slicker antennas on our radios at the same time.
Indoors is a strange place when it comes to FM signals.
Hey, maybe the antennas should be outdoors?
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Post by Deleted on Sept 11, 2017 3:30:33 GMT
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Post by thelegacy on Sept 11, 2017 17:09:47 GMT
Paid a lot less for my Outside Ground Plane antenna. However could be nice for apartment dwellers who are not allowed an outside antenna.
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Post by Deleted on Sept 11, 2017 18:08:08 GMT
Ordered a GP32 FM AntennaJust placed an order for a GP32 Decade FM Dipole Antenna. Committing to an all horizontal system. You might like to see the manual GP32 Decade FM Antenna Manual
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Post by Deleted on Sept 12, 2017 23:00:45 GMT
First Horizontal Results
We have pushed all the whips and wires in the building into horizontal positions for FM transmission and reception.
So far as it goes there is no observed difference between having the whips vertical or horizontal.
The signal levels remain the same as sampled by a spectrum analyzer and the dBu read-out on the TECSUN PL-310.
Any tendency for multi-path caused by human activity is the same.
What is noticeable is that the rooms no longer have a sea of vertical whips sticking up all over the place. The horizontal placements are completely blended into the scene.
As we move forward we will be improving the antennas for best matching and low SWR (Standing-Wave-Ratio), which of course will necessitate rolling the RF power a lot lower.
Oh, that was fast... the Decade GP32 antenna just arrived. Stay tuned!
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