Ramsey FM transmitter advice

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mikem
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Ramsey FM transmitter advice

Post by mikem » Sat Jun 20, 2009 1:38 pm

Just ordered a Ramsey FM 25 FM radio transmitter to broadcast the audio into a park for a outdoor movie, so that I won't have to amplify the sound so loud--people could use their walkman-type radio headsets.

Anybody have any advice or tips for me from their experiences? Anybody build one of these?

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dacflyer
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Re: Ramsey FM transmitter advice

Post by dacflyer » Sun Jun 21, 2009 10:33 am

i have me a whole house transmitter, made by www.wholehousetransmitter.com and it will easily transmit the whole block in my neighbor hood..so if you got the bigger one, you will obviously transmit farther.. just beware of the FCC limitations and rules.

mikem
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Re: Ramsey FM transmitter advice

Post by mikem » Sun Jun 21, 2009 2:04 pm

It comes with a collapsable whip antenna and puts out up to 25 MW. Not sure how that fits into the FCC rules. It has digital tuning so it won't drift off frequency with a DRO. I think that the FCC rules talk of Effective Radiated Power. Not sure if this is over the limit or not?

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jwax
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Re: Ramsey FM transmitter advice

Post by jwax » Sun Jun 21, 2009 3:43 pm

The site I looked at said it was selectable output power: 10 mW or 100 mW. That 100 mW ought to fill your audience (an acre or two?) with a tuned whip and good grounding no problem.
Wouldn't worry about the FCC unless some whiner in the neighborhood is getting your signal over his, so just tune way high or way low on the band where there's no other signals.

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CeaSaR
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Re: Ramsey FM transmitter advice

Post by CeaSaR » Sun Jun 21, 2009 8:05 pm

You could use this (>Vacant Station Locator<) to help find unused stations in
your area. Just enter your Zip Code or City and State to find them. Of course,
it is always good form to verify that they truly are unused.

I used to know thw FCC rule right off the top of my head, but I can't remember
it at the moment. It can't be above so many "mv" or "uv" at "X" amount of distance
from the transmitter. But that was for the "personal" type of transmitter. LPFM allows
greater coverage allowing the broadcast to cover a small to moderate size town. I'd
dig deeper into it before going on the air. Ramsey has some good links and info. Go
back to them for a start. Better safe than FCC non-compliant, I always say...

CeaSaR
Hey, what do I know?

FOB
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Re: Ramsey FM transmitter advice

Post by FOB » Fri Jun 26, 2009 9:16 am

I built one several years ago...still works. 25 mW covers my entire yard (9 acres) furthest point from the house is about 900 ft. I used 107.7 Mhz cuz there was nothing there. I usually drive it with a cd player going thru an amp with line level out. The only problem I remember was during construction I forgot to solder the shield of a tuned inductor to the pc board. Caused funny noises, but worked fine after the shield was grounded. I use a homemade dipole antenna 24" each side of center ... fed with RG-58 at the 30' level of a 100' tower. Used a WELL filtered homemade 1A. power supply based on a LM340-12. You will get 60 hz noise if there is ripple in the power sourse. Or use a battery...it does'nt need much current.
The FCC allows you 100mW without a license, so don't put it on top of a commercial station and you should be OK. Remember, the FCC is COMPLAINT driven ... if somebody bitches enough, you're gonna hear about it.
If you use more than 1 audio source, you should use some kind of equalizer because there is usually a difference. That's it....Commercial-Free sounds for mowing the lawn.
...Bob...

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