[amsat-bb] Low-Power FM (broadcast band) Transmitter?

[Matthew Chambers]

One of the guys on the other group I belong to brought up how some of the
drive-in theaters he worked with operated their system. They had a
transmitter that they hooked up a long run of "leaky" coax to with a 50 ohm
resistor at the far end. The coax was buried under the field where the cars
parked and radiated along it's entire length. No one place exceeded Part 15
limits but the whole area had enough signal to be picked up on all but the
worst car stereos.
Matthew Chambers, CBT, NR0Q
Owner/Engineer
*M Chambers Communications Engineering LLC*
PO BOX 855, Moberly, MO 65270
Mobile (660)415-5620
www.mchambersradio.com



On Thu, Apr 2, 2020 at 3:54 PM Jim Walls via AMSAT-BB <amsat-bb at amsat.org>
wrote:

> On 04/02/2020 11:27, Scott via AMSAT-BB wrote:
> > Can anyone recommend a low-power transmitter for broadcast on the
> commercial FM radio band?  An LPFM license can be acquired asap, but the
> first order of business is finding some hardware.
> >
> > As you can imagine, church gatherings are out of the question so I've
> been asked to see if I can locate a "drive-in theater" type transmitter for
> short-range broadcasting to car radios.
>
> Getting a LPFM license is not as easy and fast as you think.
> As for Part 15 transmitters, there are lots of them out there. There are
> also many available that are claiming to be license free, but not really
> meeting the Part 15 limits (especially if you put a "real" antenna on
> them).  One of my other addictions is running a music synchronized
> Christmas light show.  Almost every person running a music synchronized
> light show is running their music over an FM transmitter - sometimes in
> addition to outdoor speakers. There are several very commonly used
> transmitters.  Search Amazon for CZE-05b and you will find lots of hits
> - that's what I'm using. In my case, I have a homebuilt "real" antenna,
> but I put a in line attenuator between the radio and the antenna to keep
> at least close to Part 15 limits.
>
> As for the drive-in theaters, my assumption is that they are supposedly
> operating under Part 15, but I would be willing to bet that a lot are
> exceeding the field strength limits of Part 15 by at least a bit -
> directional antennas come to mind.  I do know that the last time I did a
> FCC license search for the FM band, the nearest drive in theater (with
> their four screens) did not show up in a licensed listing.
>
> --
> 73
> -------------------------------------
> Jim Walls - K6CCC
> jim at k6ccc.org
> Ofc:  818-548-4804
> http://members.dslextreme.com/users/k6ccc/
> AMSAT Member 32537 - WSWSS Member 395
>
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