FM transmitters for 410 to 470 MHz

Are there any FM audio transmitters for 410 to 470 MHz?

Part 15 allows for a field strength of 200uv/m@3m for any type of use between 410 and 470 MHz.  That range falls on cable channels 55 to 64.  If FM audio was transmitted on one of the audio carriers for those cable channels, someone could listen to it on their television.

Trying to send an NTSC video signal with a field strength of 200uv/m@3m would not go very far.  However, if all that allowed signal was used for audio, it is only 50uv/m less than what is allowed in the FM radio band.

410 to 470 MHz overlaps the 70cm amateur band (420 to 450), so only the audio carriers for channel 55, maybe 56, 62, 63, and 64 would be “safe” to use.

Not all TV’s would like receiving that sort of audio.  TV’s that go to a blue or black screen without a NTSC video signal would not work.  TV’s that had to be put into an over the air or a cable mode would be difficult for people to receive audio with.  On the other hand, I have a LG HDTV that will show snow on analog channels, and it will scan over the air and cable channels and show anything it finds for both; it also has an easy way to manually add channels.  It will happily play audio on a channel where the video is snow.

The 50uv/m less than the FM radio band may be made up for in antennas.   Even with 410 to 470 being outside the UHF broadcast band, if I did my math right, it looks like an 8 bay antenna may have 6 to 8 dBd of gain at those frequencies.  (For comparison, the FM6, one of the last off the shelf FM antennas, only has 5 to 7 dBd of gain in the FM band.)

So, the trick would be finding a transmitter that could put out a horizontally polarized (to match TV antennas people have on their roofs) FM audio signal on carriers of 413.75, 419.75, 455.75, 461.75 or 467.75 MHz with a field strength of 200uv/m@3m.