C Crane FM Transmitter to what receiver?

Somewhere there will have to be a power line going up to the TX. You could use that same power wire to send the audio signal by isolating the injected audio on the line with .1uF caps on both ends. Works good for short run setups. Wireless way...maybe one of those wireless headphone units would work and sound better than a small FM radio. (27Mhz FM wireless headphone)

RFB

I am weary of mixing power and audio and ideally wanted the transmitter stack isolated from house as much as possible. Trying to keep things literal and obvious so other folks can cheaply and non-technically maintain things in the future.

To this effect, the transmitter when finally perfected and placed in its final home will run offgrid via battery / DC power. Might be necessity if I place the transmitter in our other lot where power is unavailable and running such, cost prohibitive (monthly new metered service).

Cheap wireless headphones for wireless STL option

RFB

Don't waste time with a C.Crane. They have a stubby antenna that is not suitable for penetrating walls or reaching more than 10-feet.

Get a Wholehouse 2.0, which has instructions for adding a 1/4 wave antenna tuned to the exact frequency.

Also, there is a hidden switch under a round sticker in the battery compartment that boosts the power in case the low setting is not enough.

The receiver is another matter, and since you need a low cost receiver located outdoors I have no solution.

So, let's build on RFB's good ideas...

In his version of placing power and audio on the same wire, that would only work with D.C., as obviously AC would be loud hum.

If your audio lines were balanced, you could send the power in the phantom configuration used by many condenser microphones, which also works well.

The headphone idea has been successfully done by Tha Dood, part 15 in Poca, West Virginia, using an inexpensive Radio Shack model at 49mHz.

He has had only one problem, a lot of 49mHz baby monitors are in use in his area, so you'd need to monitor 49mHz to pick the most quiet channel.

"In his version of placing power and audio on the same wire, that would only work with D.C., as obviously AC would be loud hum." Answered in the following...

"
If your audio lines were balanced, you could send the power in the phantom configuration used by many condenser microphones, which also works well."

Sums it up very well. As I stated, short runs is not a worry about hum. If the run is long, balanced is the way to go. And on top of that, your feeding DC down the wire, not AC other than the audio signal.

I've used the 27Mhz wireless headphones (cheap ones) with no interference issues even sitting here less than 1 block off I-25. If your hop is short..ie within 50 feet or so, no problems. Any further than that and you might as well consider running the wire option, or find a wireless solution which allows for more power from a license free device, but having good audio quality will be a bit tough.

RFB

Don't waste time with a C.Crane. They have a stubby antenna that is not suitable for penetrating walls or reaching more than 10-feet. Get a Wholehouse 2.0, which has instructions for adding a 1/4 wave antenna tuned to the exact frequency. Also, there is a hidden switch under a round sticker in the battery compartment that boosts the power in case the low setting is not enough.

Just a friendly reminder to unlicensed operators wishing to comply with FCC 15.239 -- the combination of transmitter power output plus transmit antenna configuration used in this application is unimportant.

The only requirement given in FCC 15.239 is that the field intensity radiated by an unlicensed system in the FM broadcast band cannot exceed 250 uV/m at a distance of 3 meters in any direction from the transmit antenna.

The compliancy measurements being brought to attention are applicable outdoors in public space, and the FM transmitter in our above discussion is located indoors beamed up to the roof of the same house on private property.

But of course some attention would need to be given to the public streets and sidewalks beyond this house.

Everyone knows that already, but maybe not...

The compliancy measurements being brought to attention are applicable outdoors in public space, and the FM transmitter in our above discussion is located indoors beamed up to the roof of the same house on private property. But of course some attention would need to be given to the public streets and sidewalks beyond this house. Everyone knows that already, but maybe not.

Just to note that FCC Part 15.239 does not limit the fields radiated by an unlicensed operator using the FM broadcast band only to those fields that might be radiated toward, or received in locations accessible by the general public.

Those headphones seem to have lots of negative reviews. Sound spectrum / range seems limited.

Unsure how I'd get the headphones apart and rebundled to run off direct DC plus pipe the audio out to the audio input on the AM transmitter. Seems like quite a bit of complexity and likelihood for breakage is great.

Considering how wire runs tend to go around here, my run from the mixer (in basement in building next door) to the transmitter (on top of other building) --- the run is rather long.

Have about 75 feet across to cover, another 40 ft to rear of structure then probably another 15 ft vertical plus another 10ft to reach the transmitter. Probably in 125-150ft range total. Line losses and drops are a concern at that length (maybe I am being overly worried there).

Comparatively, the FM transmitter route seems way shorter. I can go out of the basement where the mixing console is and up the side of the building and put the FM transmitter there where possible that the top of the AM antenna would be in line of site of the FM transmitter although some 40ft roughly apart. Cable run would be 15ft interior plus 20ft vertical exterior for 35ft approximately. That is more reasonable.

Still dealing with building holes and need to ground and lightening issues.

In ideal world we'd do a FM transmitter in building to FM transmitter outside to FM receiver coupled to AM transmitter.

Get your legal opinions from RF engineers.

Just curious about a general consensus as to whether or not the quote below is not presented as a legal opinion, and one which is not supported by FCC 15.239.
_________________

The compliancy measurements being brought to attention are applicable outdoors in public space, and the FM transmitter in our above discussion is located indoors beamed up to the roof of the same house on private property.

Carl, I don't think the Whole House is legal. Maybe the 2.0 version somehow is. Even if it is FCC compliant, the power boost and the 1/4 wave antenna seem out of compliance.

The importer/reseller was cited by the FCC in 2009 forfeiture action for $18k for long existing infractions. Unsure if the board in question was the one in the Whole House or if it was the Drive By FM transmitter. That action points to the Whole House and I assume that was a WH 1.x version.

---------------------

Richfield did not state when it
began shipping the WH Transmitter to TAW or specify the total number
of units it manufactured and shipped to TAW, but TAW previously
indicated that it began importing the device in May 2004 and that it
imported a total of 18,371 units and distributed a total of 11,689
units in the U.S. Richfield indicated that the device has been
certificated in accordance with the Commission's equipment
authorization procedures. In its Further LOI Response, Richfield
admitted that after the device was certificated it modified the
device's antenna to improve "sound quality." Specifically, Richfield
explained that the antenna modification involved a "flexible copper,"
1.5 meters in length. According to Richfield, it did not realize that
the antenna, as modified, would cause increased field strength
emission levels. Richfield claimed that it began modifying the antenna
in December 2008 and that only the final 2,500 units shipped to TAW in
February 2009 had the modified antenna. We note, however, that the
sample WH Transmitter tested and found to be non-compliant by OET was
purchased and tested in May 2008 - approximately seven months prior to
December 2008. Finally, Richfield stated that it began labeling the WH
Transmitter with the FCC ID on December 17, 2008, at the request of
TAW.

The FCC action document is found here:
http://transition.fcc.gov/eb/Orders/2009/DA-09-2303A1.html

How 'bout an abandoned cordless phone with an intercom feature.

Maybe an old battery operated baby monitor.

Then there's the old wireless microphone slightly modified to accept audio input.

How about a carrier current transmitter coupled to the power cable running up there with a small battery AM radio.

Thanks as always @mram1500.

Well, what I've decided to do, albeit in the FCC fringe is this:

1. Go with the Whole House transmitter.
2. Refuse to pay $100-125 for such.
3. Picked up a transmitter board from TAW Global, the makers/importers of the Talking House (selling on Ebay).
4. The board is the FCC Part 15 certified (FCC ID # QKQRF-2001), the same one that caused TAW Global that $18k FCC forfeiture action.
5. Paid price $14 delivered.

Specs look the same as the Talking House unit. I suspect this board was what was in the TH v1 units. The antenna looks stock and proper at just a few inches.

Broadcast Distance of up to 200 foot radius
Runs on 5V DC (for example Computer USB, 3 "AA" Batteries, 110V to 5V AC power supply, etc.
3.5mm (1/8") Stereo Headphone Jack
3 Dip Switch Frequency Selection (7 frequencies of 106.7 through 107.9)

Lose the full FM band flexibility and limited to those frequencies. No fancy LCD screen.

But better in my opinion for this use as hard dip switched settings. Plus, with no case bulk I can embed this however without fear of breaking things. Since it runs 5V DC this will likely be my first build part for the station and the first totally off grid solar powered piece.

You appear to have already made your decision, but one perfectly legal way to accomplish what you want to do is to use 802.11 wireless over an intranet. You can use an inexpensive internet radio receiver at your transmitter site to capture the stream. There are some internet radios out there that can use battery power and almost all use DC. You can easily achieve several hundred feet distance (legally) by using directional antennas at your home studio, pointing to the receiver.

I used this method once when mounting a transmitter well away from the studio. I put an older Roku internet radio in the weatherproof box along with the transmitter - I did have access to power (but did not have to worry about running hundreds of feet of audio cable).