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 Post subject: What is this FM frequency used for??
PostPosted: Mar Sat 03, 2018 1:48 am 
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30-50 MC on a FM communication receiver.


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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Sat 03, 2018 2:35 am 
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FM radio in the years 1940 to 1945:
https://en.wikipedia.org/wiki/FM_broadc ... ted_States

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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Sat 03, 2018 2:40 am 
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The 30 - 50 MHz FM band is (or was) used for such things as police radio, taxicabs, cordless phones, baby monitors, railroads, and similar stuff. Most of this has moved to higher frequencies.

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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Sat 03, 2018 2:41 am 
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That was an old public service band used for quite some time for police, fire and so on before they went to the higher VHF band and currently to UHF, it is very rarely used today except in a few small towns, so not much market for those sets.

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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Sat 03, 2018 3:11 am 
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Because they have had very little use over the years I usually see those radios in very clean condition. They make great "shelf queens".


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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Sat 03, 2018 3:16 am 
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Where I live, the old FM band is basically silent dead space.

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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Sun 04, 2018 8:04 am 
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Could they be converted to another better use?
I dont have any ideas, just wondering.
Mark Oppat


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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Sun 04, 2018 3:58 pm 
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I am not sure what there is as a practical advantage of some service that is not trunked, dumping low band and going to higher freqs, other than the fact the antennas are more manageable. And I guess sometimes you get interference from wave propagation. In high sunspot years there might be junk coming in from Mexico or South America on the freqs. A walkie talkie would have a pretty cumbersome antenna to be practical on that band. I have seen the 70 MHz talkies in Europe and they have ridiculous flex whips. Otherwise mobile units can dispense with the full sized whips and use base loaded whips like CB to keep the antennas shorter. The technology that allows trunking and digital would function just as well down there but I think everyone is NMFM probably, still. The band has shifted from critical stuff like fire and police to utilities, railroads, etc. etc. as far as I know. Maybe some volunteer FD still on there. Have to check the scanner listings in your area. Maybe some military too. Better use? I suppose if you could shift the tuning at the top end to reach all the way to 53 MHz, you could hear hams on FM in some areas, but even that will not enhance the value much, I guess.


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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Sun 04, 2018 5:04 pm 
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I refurbished a Pioneer SMB200 AM/FM chassis sometime ago (that's another topic!) However, the FM band on this Rx is 80 to 108 MHz (not 88 to 108, as now.) What stations were there between 80 and 88 MHz? Was it, or is it, a TV channel?
Cheers,
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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Sun 04, 2018 5:06 pm 
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The LF FM two-way band was commonly used for organizations that covered a large geographic area, like state police departments. Maryland state police still have radios in that band.

- Leigh

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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Sun 04, 2018 5:20 pm 
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engineer wrote:
What stations were there between 80 and 88 MHz? Was it, or is it, a TV channel?
Yes, TV channels 5 and 6 would be in that part of the spectrum here in the USA.

I do know, years ago, the State Highway Patrol used a frequency near 45 MC. It was meant as a universal frequency which all states would use to communicate with each other. The problem was the frequency is so rarely and intermittently used, finding a transmission would be like finding a needle in a haystack.

I have one of those LowBand VHF receivers and back in the 80s would hear all kinds of weird sounds which might have been paging signals, but to me they sounded like some crazy Arcade game.

I would imagine the spectrum still has some use, but probably all but abandoned for more fertile ground in the UHF spectrum. That of which has taken a HUGE bite out of the spectrum previously allocated to OTA TV.

-Steve

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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Sun 04, 2018 6:54 pm 
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Now mostly obsolete. I have old military and amateur rigs that cover the 6 meter band. Narrow-band FM (NBFM) on some of them.
I have an old Bearcat with VHF-Lo crystals in it. Very little to hear in the way of public or civil safety on it.


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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Mon 05, 2018 12:54 am 
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Many fire departments still use frequencies in the 46-47 Mhz band for wide area paging.
Also, it was once considered "high Frequency" during the late 1930's. Many police departments moved up there from the 1700 & 2400 Kcs band, first in AM then in FM, where they used 2 way radio. The upper part of the band, as mentioned by a previous poster was the original FM broadcast band. Police Communications on that low band were quite numerous until the mid 1970's when most departments went to High Band 150-174 Mhz and UHF 450-470 Mhz.

One of the major problems with 30-50 Mhz was the inability to produce a decent portable radio for officers to use (you could yell further than most of those walkie talkies could communicate). The other was intense "skip" when the band was open.

In my area, the West Milford NJ Police still use 37.02 for communications, using 37.24 as an input and VHF/UHF car repeaters to extend the range of the portable radios. They sound surprisingly good!

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Last edited by Mike DeMeo on Mar Mon 05, 2018 1:11 am, edited 1 time in total.

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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Mon 05, 2018 1:05 am 
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Well hoffies2, here's the frequencies used in your county and a few of them hover around 46 MHz. https://www.radioreference.com/apps/db/?ctid=307

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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Mon 05, 2018 1:43 am 
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Indiana Radios wrote:
Well hoffies2, here's the frequencies used in your county and a few of them hover around 46 MHz. https://www.radioreference.com/apps/db/?ctid=307

Amazing how you dig up this info. Appears the 46 MHz. frequency is still used by many fire departments, emergency and public works. From the replies I figured it was a lost art.
Thank you.


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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Mon 05, 2018 2:41 am 
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Well hook about 6 feet of wire to the back and stretch it up vertically behind the radio and see what you can hear.


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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Mon 05, 2018 2:56 am 
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Indiana Radios wrote:
Well hoffies2, here's the frequencies used in your county and a few of them hover around 46 MHz. https://www.radioreference.com/apps/db/?ctid=307


Are those analog FM, or some sort of PCM or packet system? I was under the impression that emergency radio systems were all made digital and interoperable after 9/11, or at least that was the goal.

Brett


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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Mon 05, 2018 3:05 pm 
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Brett_Buck wrote:
Indiana Radios wrote:
Well hoffies2, here's the frequencies used in your county and a few of them hover around 46 MHz. https://www.radioreference.com/apps/db/?ctid=307


Are those analog FM, or some sort of PCM or packet system? I was under the impression that emergency radio systems were all made digital and interoperable after 9/11, or at least that was the goal.

Brett


Mostly all analog FM if you are talking about 30-50 Mhz. Many area fire departments still use the 46 Mhz range along with UHF frequencies assigned to a particular department. Some departments have a tie in, meaning a base station at the firehouse or some other location, that receives transmissions on a selected UHF channel and re transmits it to a low band base station via a carrier operated connection on the counties low band channel, and vice versa. This facilitates communication from a portable at the scene to the counties main fire control.

Some fire departments that have migrated to digital systems still maintain these systems, using the digital systems to coordinate with other emergency services (police, ems). When I was involved with the digital public safety system planning (early 2000's) the analogs were kept operational because they could not tone out volunteers on digital. I do not know if that has since been overcome.

As for post 9/11, some steps were taken towards interoperabilty. A chunk of spectrum from the former analog TV channels (760 Mhz area) was given to Public Safety to implement spectrum efficient countywide digital systems. Highband frequencies were narrowbanded to allow for more channels, some of those going digital. There is still a long way to go in most parts of the country

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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Mon 05, 2018 3:12 pm 
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After all is said and done, why the hesitancy to just connect an antenna and tune around?

This is, after all, how I found out what was on different bands. This is indeed the fun part! :D

-Steve

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 Post subject: Re: What is this FM frequency used for??
PostPosted: Mar Mon 05, 2018 3:35 pm 
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azenithnut wrote:
After all is said and done, why the hesitancy to just connect an antenna and tune around?

This is, after all, how I found out what was on different bands. This is indeed the fun part! :D

-Steve


And don't forget that the military still uses quite a few frequencies on this band although they are widebanded. Just look at the antennas on some of the National Guard vehicles. That shouldn't matter as Lafayette Radio is tunable.

I read somewhere that some military communications from the European Theater were copied in New England during the later part of WW2!

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