FM Transmitter Antennae

[Steven]

rescue_653 wrote:

For one thing FM transmitters do not ransmit in the same frequency as the radios in Aircraft which if I remember correctly is VHF.

Both FM broadcast and the aircraft band are VHF. FM broadcast is 88 to 108 MHz. Aircraft is about 108 to 136 MHz. That's why it's good to use a transmitter with a "clean" output (like the EDM) that won't "splatter" to out-of-band frequencies.

[PMC]

Steven wrote:

rescue_653 wrote:

For one thing FM transmitters do not ransmit in the same frequency as the radios in Aircraft which if I remember correctly is VHF.

Both FM broadcast and the aircraft band are VHF. FM broadcast is 88 to 108 MHz. Aircraft is about 108 to 136 MHz. That's why it's good to use a transmitter with a "clean" output (like the EDM) that won't "splatter" to out-of-band frequencies.

+ 1 Steven, what you said is very important!

Splatter is also called the harmonics that come off of those China produced FM Transmitters that can effect anything in the aircraft band and beyond,

example, one of my stations that I work for broadcasts on 96.9 FM and I got a call from Sprint saying I was interfering the 935 MHz band, that would be my 13th harmonic of 96.9FM I found what was causing the spur and fixed it. but I was causing problems for a cellphone provider even though I was on 96.9 FM and I was responsible for the cause since I was licensed with the FCC I had 48 hours to fix the problem, I fixed it in 2 hours

how did Sprint know it was me? simple they have very nice detecting equipment that finds all of these "problems" its a great looking van with $100,000 worth of equipment in them

If you operate a 1watt to 100watt illegal station these are the things you don't want to be caught at, and yes you could effect FCC licensed equipment (cellphones, computers, etc) just around your neighborhood. This is why it is important to be legal

okay, I'm done with this subject

[rescue_653]

Steven wrote:

rescue_653 wrote:

For one thing FM transmitters do not ransmit in the same frequency as the radios in Aircraft which if I remember correctly is VHF.

Both FM broadcast and the aircraft band are VHF.  FM broadcast is 88 to 108 MHz.  Aircraft is about 108 to 136 MHz.  That's why it's good to use a transmitter with a "clean" output (like the EDM) that won't "splatter" to out-of-band frequencies.

I couldn't remember exactly how low the frequency went on aircraft.

[JBullard]

Aviation uses AM and digital signals. While none would be able to hear your christmas music broadcast as FM, severe interference could occur with the navigation frequencies. The EDMs operated as Greg stated, will not cause any problems. The ones from China ? who knows.

More detailed allocation:

108.000-
112.000 MHz Aviation Terminal VOR and ILS Navigation (80 Channels)
112.000-
117.950 MHz Aviation VOR Navigation (120 Channels)
118.000-
136.000 MHz Aviation Communication (720 Channels)
121.500 MHz Aviation Distress
121.600 MHz Civil Air Patrol (Authorized use only)
121.700 MHz Aviation Ground Control
118.000-
121.400 MHz Air Traffic Control (Towers and ARTCC's)
121.600 MHz Civil Air Patrol Training Beacons
121.650 MHz Aviation Ground Control
121.700 MHz Aviation Ground Control
121.750 MHz Aviation Ground Control
121.775 MHz Civil Air Patrol Training Beacons
121.800 MHz Aviation Ground Control
121.850 MHz Aviation Ground Control
121.900 MHz Aviation Ground Control
121.900 MHz Flight Schools
121.957 MHz Flight Service Stations
122.000 MHz Flight Advisory Service
122.025-
122.675 MHz Flight Service Stations
122.250 MHz Balloons
122.400 MHz Flight Service Stations
122.600 MHz Flight Service Stations
122.700 MHz Aviation UNICOM Uncontrolled Airports
122.725 MHz Aviation UNICOM Private Airports
122.750 MHz Aviation Air to Air Communications
122.775 MHz Air Shows & Air-to-air Communications
122.800 MHz Aviation UNICOM Uncontrolled Airports
122.825 MHz ARINC
122.850 MHz Aviation Multicom
122.875 MHz ARINC
122.900 MHz Aviation UNICOM Uncontrolled Airports and Search and Rescue Training
122.925 MHz Aviation UNICOM/Multicom/Air Shows
122.950 MHz Aviation UNICOM Controlled Airports
122.975 MHz Aviation UNICOM
122.975 MHz Airplane to Airplane (high altitude airliners)
123.000 MHz Aviation UNICOM
123.050 MHz Aviation UNICOM
123.050 MHz Aviation Heliports
123.075 MHz Aviation UNICOM
123.075 MHz Aviation Heliports
123.000 MHz Aviation UNICOM Uncontrolled airports
123.025 MHz Helicopters Air-to-air Communications
123.050 MHz Aviation UNICO Heliports
123.075 MHz Aviation UNICOM Heliports
123.100 MHz Search and Rescue/Civil Air Patrol
123.125-
123.476 MHz Flight Test
123.200 MHz Flight Schools
123.300 MHz Flight Schools & Balloons
123.325 MHz Air Shows
123.350 MHz NASA
123.400 MHz Flight Schools
123.425 MHz Air Shows
123.450 MHz Air to Air (trans-ocean unofficial)
123.475 MHz U.S. Army Golden Knights
123.500 MHz Flight Schools & Balloons
123.525-
123.575 MHz Flight testing
123.600-
128.800 MHz Air Traffic Control (Towers/ARTCC's)
126.200 MHz Military Airport Towers
128.625 MHz NASA/NOAA Research
128.825-
132.000 MHz ARINC
130.650 MHz Military Airlift Command
134.100 MHz Military Airports - Ground Control Approach (GCA) Radar
135.850 MHz Federal Aviation Administration (FAA)
135,950 MHz Federal Aviation Administration (FAA)

[hdracer]

I'm glad some of you pros on this have spoken up! I would really hate for them to come around and take my fun away!
Now I know to stick to my guns and buy an EDM...

[Guest guest]

If you use the appropriate antenna, with a good clean transmitter like an EDM, you have nothing to worry about.

[PMC]

a common sense rule would apply,

use your EDM, or other very low power FM Modulator and drive around listening to your "station" if you hear it over a block away and it starts to fade, chances are your okay. if not move your antenna around or use an 6 dB attenuator to pad down the RF coming out of your transmitter

when I built my first FM kit (30+ years ago) , I received it 2 miles away, and that was when the unit was sitting on my workbench with a dipole antenna sticking out of it.
needless to say, I used it as an exciter for one of my older transmitters and it worked well for years

But, Last but not least..... Processing = Modulation, make your station loud, you will be surprised with the results.

download that Breakaway Audio Enhancer and it comes with a 30 day free trial and do a before and after install test, you will be amazed

[JBullard]

The EDM engineers generally do NOT recommend external processing with their transmitters in an attempt to boost modulation.

These are designed to be the village radio station in many parts of the world, and output a very hot clean signal right out of the box.

Without proper knowledge (such as PMC does have, and uses with his non EDM transmitter) extra modulation can cause the EDM to sound like crap. My suggestion is to use it as it was designed without external enhancements for the best results.

[Max-Paul]

Just a bit of info, maybe useless as it is, but info just the same.
3-30Mhz is High Freq.
30-300Mhz is Very High Freq.
300-3000Mhz is Ultra High Freq.
3-30Ghz is Super High Freq.

At least that is what they taught me in the Air Force over 30 yrs ago. Things might have changed.

[Steven]

Max-Paul wrote:

3-30Mhz is High Freq.

Don't forget the US AM Broadcast band, which is part of
300kHz-3MHz Medium Frequency

[JBullard]

And dont forget the low and ultra low freqs below the AM broadcast band that gets heavy use for deep ocean comms with submarines and orher military and scentfic purposes

[Max-Paul]

Actually Steven as I remember it.

.3-3Mhz is Low Frequency and
3-300Khz is Extremely Low Frequency, AKA ELF

I dont remember any Medium Frequency.

[Max-Paul]

Well, my memory has slipped on the lower frequencies.

You are correct .3-30Mhz is medium Freq.
And I need to correct my info
30-300Khz is L.F. and
3-30Khz is E.L.F.

One of my teachers would at a Navy ELF site. He said it transmitted in the 18Khz range and some people could actually hear the transmission.

[PMC]

This thread is about as bad as the forums I hang out on for radio and all we talk/type about is this and where radio is heading, processing, old transmitters, and remember these people... I'm sure Dan is loving this

[Max-Paul]

PMC,
KWM-2A, I hate those little "door knob" capacitors that I had to tune. Dang things got oxide on the contacts and where jumper than heck. So, in some ways I do love the digital stuff. Only real difference is that at least with the older stuff you could repair them. Dang digital stuff goes crazy. Best for your own sanity is pitch the digital and buy new. LOL