Search found 17 matches

by Paul678
Thu Dec 29, 2016 8:38 pm
Forum: FM Radio
Topic: A Way Around the LPFM International Border Agreement?
Replies: 4
Views: 520

Re: A Way Around the LPFM International Border Agreement?

You'll have to get it cleared by Mexico. Sometimes that is easy, sometimes it takes 10 years. Attached is the relevant bit of the US-Mex FM Broadcasting Agreement. Ok, thank you for that info. Clearly, Tucson is within about 75 Kilometers of the common border. But going to 100 Watts requires approv...
by Paul678
Thu Dec 29, 2016 2:00 pm
Forum: FM Radio
Topic: A Way Around the LPFM International Border Agreement?
Replies: 4
Views: 520

A Way Around the LPFM International Border Agreement?

In Tucson, LPFM stations are restricted by the International Border Agreement, and are limited to 50 Watts transmitter output. Phoenix stations are not bound by that same restriction. They're allowed to broadcast at 100 watts. However, there is an LPFM station in Southern Tucson, that broadcasts at ...
by Paul678
Fri Nov 11, 2016 1:06 pm
Forum: FM Radio
Topic: Theory Discussion: Circular Polarization Vs. Vertical Polarization
Replies: 46
Views: 2495

Re: Theory Discussion: Circular Polarization Vs. Vertical Polarization

But aren't these archaic rules a bit silly, if the booster can supply nearly all the required signal? Can't they re-write the rules for modern, high-Q filters with better out-of-band rejection? And even if the booster is less than 20% of the ERP of the main transmitter, there will still technically...
by Paul678
Fri Nov 11, 2016 12:29 am
Forum: FM Radio
Topic: Theory Discussion: Circular Polarization Vs. Vertical Polarization
Replies: 46
Views: 2495

Re: Theory Discussion: Circular Polarization Vs. Vertical Polarization

Interesting drift of topics. Regarding stereo vs mono: This is simple math. Modulation index determines signal to noise. With stereo the index is 1.5 for a case where the transmitter is modulated single channel at 100% modulation. For mono the modulation index is 5. I have put on stations where we ...
by Paul678
Wed Nov 09, 2016 1:36 pm
Forum: FM Radio
Topic: Theory Discussion: Circular Polarization Vs. Vertical Polarization
Replies: 46
Views: 2495

Re: Theory Discussion: Circular Polarization Vs. Vertical Polarization

That's crazy! If I understand you correctly, the booster could be made into the main transmitter, and the listeners wouldn't notice the difference! True: they could shut down the main transmitter & operate only the booster and nearly all the audience wouldn't notice the difference. It would however...
by Paul678
Wed Nov 09, 2016 9:53 am
Forum: FM Radio
Topic: Theory Discussion: Circular Polarization Vs. Vertical Polarization
Replies: 46
Views: 2495

Re: Theory Discussion: Circular Polarization Vs. Vertical Polarization

[img]http://www.w9wi.com/images/KRRN.jpg Legal reasons. See the image. (assuming it works :) if not, try http://www.w9wi.com/images/KRRN.jpg ) We're looking at KRRN, 92.7MHz in Las Vegas. Legally, KRRN is NOT a Las Vegas station -- it's authorized to serve Moapa Valley, Nevada. KRRN cannot locate i...
by Paul678
Tue Nov 08, 2016 4:50 pm
Forum: FM Radio
Topic: Theory Discussion: Circular Polarization Vs. Vertical Polarization
Replies: 46
Views: 2495

Re: Theory Discussion: Circular Polarization Vs. Vertical Polarization

The impression there are an unusual number of these horizontal-only stations in Nevada does seem accurate. 14.7% of the FM station license records in the FCC DB for Nevada specify no vertical power. In most other Western states the figure is closer to 5%. (it's 9.5% in Utah - which one might expect...
by Paul678
Tue Nov 08, 2016 4:42 pm
Forum: FM Radio
Topic: Theory Discussion: Circular Polarization Vs. Vertical Polarization
Replies: 46
Views: 2495

Re: Theory Discussion: Circular Polarization Vs. Vertical Polarization

Why are you so hung up on Bessell functions? You sound like a man whose only tool is a hammer and to whom every problem looks like a nail. Have you ever made practical use of a Bessell function in broadcasting, say, by using it to calibrate an FM modulation monitor? I'd rather have a hammer, than a...
by Paul678
Mon Nov 07, 2016 3:49 pm
Forum: FM Radio
Topic: Theory Discussion: Circular Polarization Vs. Vertical Polarization
Replies: 46
Views: 2495

Re: Theory Discussion: Circular Polarization Vs. Vertical Polarization

Now back to the LPFM example...the approach is the same. LPFM's are limited to 100 watts at 30 meters AHAAT. While the rules do not expressly state this, the contour distance for an LPFM is 5.6 kilometers, or 3.5 miles for the 60 dbu/1 mv/m contour. LPFM's do not have a "protected contour" as a sec...
by Paul678
Mon Nov 07, 2016 2:59 pm
Forum: FM Radio
Topic: Theory Discussion: Circular Polarization Vs. Vertical Polarization
Replies: 46
Views: 2495

Re: Theory Discussion: Circular Polarization Vs. Vertical Polarization

For example, a stereo multiplex signal has the same transmitter power as a mono signal or even an unmodulated carrier, contrary to what one poster said. That's true, but a stereo signal will have to turn down it's modulation level to avoid over-deviation, because it's FM Bessel function bandwidth w...
by Paul678
Mon Nov 07, 2016 1:31 am
Forum: FM Radio
Topic: Theory Discussion: Circular Polarization Vs. Vertical Polarization
Replies: 46
Views: 2495

Re: Theory Discussion: Circular Polarization Vs. Vertical Polarization

Your "RF Friend" clearly does not have much if any broadcast experience. As an aside, those 10 watt class-Ds he cites as proof of his theory used horizontally-polarized antennas because that is what was (relatively) inexpensively available when these were licensed, and is what the equipment compani...
by Paul678
Sat Nov 05, 2016 2:03 pm
Forum: FM Radio
Topic: Theory Discussion: Circular Polarization Vs. Vertical Polarization
Replies: 46
Views: 2495

Theory Discussion: Circular Polarization Vs. Vertical Polarization

Here's what an RF friend of mine thinks: "Circular polarization is probably not the best idea for FM. Broadcasters use circular polarization because they are limited in the amount of power they can broadcast with. In some states, they are limited to 100kW on an open channel- so they usually broadcas...
by Paul678
Wed Nov 02, 2016 4:26 pm
Forum: FM Radio
Topic: Is there a High Power Version of the Comet CFM95SL 5/8 Wave FM Antenna?
Replies: 7
Views: 463

Re: Is there a High Power Version of the Comet CFM95SL 5/8 Wave FM Antenna?

Bill DeFelice wrote:
The CFM95SL is only rated to handle up to 200 Watts.
Are any of the antennas like this or the Comet even allowed for licensed FM use?
Yes, some LPFM stations have been licensed with the Comet.
by Paul678
Wed Nov 02, 2016 2:19 pm
Forum: FM Radio
Topic: Is there a High Power Version of the Comet CFM95SL 5/8 Wave FM Antenna?
Replies: 7
Views: 463

Re: Is there a High Power Version of the Comet CFM95SL 5/8 Wave FM Antenna?

jammerdave wrote:http://www.
Wow, perfect! And very reasonably priced, as it includes shipping to the USA.

Type N connector is about $193.

THANKS MUCH, DAVE!

:D
by Paul678
Wed Nov 02, 2016 1:30 pm
Forum: FM Radio
Topic: Is there a High Power Version of the Comet CFM95SL 5/8 Wave FM Antenna?
Replies: 7
Views: 463

Is there a High Power Version of the Comet CFM95SL 5/8 Wave FM Antenna?

The CFM95SL is only rated to handle up to 200 Watts.

I need a similar 5/8 Wave FM Antenna that will handle up to 1000 Watts continuously.

Thanks in advance......