87.9 MHz

Section 15.209 says that the field strength limit in the band 30 - 88 MHz is limited to "100**" uV/m at 3 m. "**" refers to a footnote that says, among other things, that the fundamental frequency cannot be in the band 76 - 88 MHz. So, operating on 87.9 MHz is not allowed at any signal level. Yes, there is an exception for short signal bursts.

Bruce MICRO1700

There may be hope.

Read especially the last entry here at this thread

http://www.part15.us/node/2311

Thank you Ermi and Carl!

I appreciate the information
very much.

I guess I won't be going down there
any time soon. Maybe someday if
the wind is blowing in the right
direction.

Best Wishes!

Bruce, MICRO1690/1700

It is a no no to transmit on 87.9 mhz given current rules.

If you look at the latest NOUO's (notice of unlicensed operation) where the stations were operating on 87.9 mhz the fcc quotes the only exception would be under part 15 rules however operation on 87.9 is not allowed at any field strength.

Now if the signal did not leave the confines of your home, say it is fed on cable* throughout your home on 87.9 fm then yes i guess it would be ok but to be safe i personally choose not to transmit down there in any capacity. I find it kind of silly though that you can operate on even or odd channels starting at 88 mhz to 108 mhz.
I feel there is a slight risk of interference if i were to transmit on 108 mhz because there is a airfield close to my house and 88 mhz would not do if it were the only channel left because there is a station broadcasting on 88.1 mhz. Now anything above 88.1 to 107.9 is okay but i try to follow one simple rule, i choose a frequency like say 95.7 because there is nothing on either side of it, 95.5 and 95.9 are clear for my area. There are several other spots on the dial i can broadcast on but 95.7 has been pretty good to me with the exception of tropospheric ducting which cannot be avoided no matter where you choose to call home on the fm dial.

Thats my take on the subject. I Hope everyone is doing well.

*I want to add that if you chose to operate through coaxial cable the field strength should be minimal at best. If you have to plug the cable into the back of the radio and cannot receive the signal without direct connection then it should be fine. The cable would be something you installed yourself and have no direct connection with any cable lines your local cable company or phone company may have installed.

There is currently no 'type certificated under Part 74' transmitter on the market that can transmit at 87.9 Mhz.
Presently, you must use a device that is type certificated under Part 74 technical requirements (47 CFR 74.861)

But, there is one such device on the market that does transmit on any frequency between 76-87.8 Mhz...the Comtek BST-25.

The FCC has waived Part 15 rules pertaining to unlicensed operation in the "core TV bands", and has temporarily allowed unlicensed use of transmitters by meeting the criteria it has established in ET Docket 10-24 (Based on Part 74 techincal rules, a revision of Part 15.3 and the addition of Part 15.238.) It clearly states that low power auxilliary stations, including wireless microphones are presently legal to use on core tv band frequencies license free by any party, until the FCC decides what it wants to do.

http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-10-16A1.pdf

The Comtek BST-25 is a low power auxilliary transmitter...and can utilize an optional remote antenna from the manufacturer. One used to need a Part 74 license to operate it. It absolutely meets all of the criteria set forth in the 'Wireless Microphone Report and Order'.

Here is another interesting article...check out the section titled 'Interim Operation', and also 'Further Notice Of Proposed Rulemaking'.

http://www.commlawcenter.com/2010/01/radio-television-and-other-users-of-wireless-microphones-must-migrate-out-of-the-700-mhz-band.html

Suppose you were to use a Comtek set on 87.7 Mhz as a transmit frequency. Would there be any question as to whether or not you are using a core tv band frequency? 87.7 Mhz was the audio carrier for analog Ch. 6. DTV stations on Ch. 6 still utilize that frequency, albeit in a different way.

50mW at the output terminals of the transmitter...pretty cool.

Stay away from 87.9 Mhz (FM Band Channel 200), secure the certificated equipment, meet the criteria established in the report and order, and go for it...after all, this is temporary, right?

It becomes real temporary, after your neighbor eventually installs a TVBD and blast 4 watts of 'Super Wi Fi' data on the same 'core tv band' frequency you want to use. 24/7/365....

It is gonna be a wild ride for a little bit, but now that TVBD / White Space decisions came down, things should get interesting.

Thank you Barry and Tbone903. I sure do appreciate
the additional information.
I guess we'll have to see what the future holds.

Best Wishes
Bruce, MICRO1690/1700

So, operating on 87.9 MHz is not allowed at any signal level.

uhhhh what about...
Licensee: ST. FRANCIS HIGH SCHOOL OF MOUNTAIN VIEW
Service Designation: FM 'Full Service' FM station or application

Channel/Class: 200D Frequency: 87.9 MHz Licensed
File No.: BLED-19990511KA Facility ID number: 62118
CDBS Application ID No.: 285006

and...

K200AA NV SUN VALLEY USA

Licensee: CALVARY CHAPEL OF TWIN FALLS, INC.
Service Designation: FX Translator Station (retransmits signal, different channel than main station)
Channel/Class: 200D Frequency: 87.9 MHz Licensed
File No.: BLFT-20060830AAE Facility ID number: 83363
CDBS Application ID No.: 1146642

Hi John:

Thanks for coming on in.

What I heard about those stations is that
they were bumped from other channels.

I guess there were no channel 6 stations
anywhere around them. Also, they are
all low ERP.

They are licensed, as you mentioned, so I
guess that's different than Part 15.

These stations have been around for a while.
FM licensed channel 200 does exist. I wonder
why the FCC never put more licensed stations
on 87.9. Maybe it was pressure from the
channel six broadcasters around the country.

Best Wishes,
Bruce, MICRO1690/1700

I should have said that UNLICENSED operation on 87.9 MHz is not allowed at any signal level. Part 73 allows licensed broadcasting on 87.9 MHz under some circumstances.

It seems the FCC has its eye on the future of 87.9: (RBR-TVBR report of NAB-RAB conference)

"If Peter Doyle, Chief, Audio Division, Media Bureau at the FCC had the authority, radio stations operating as low-power TV stations on Channel 6 licenses would be shut down already. But even though that’s under his colleagues in the Video Division, Doyle predicts that the operations won’t last much longer.

During a session at last week’s Radio Show in Washington, DC, a broadcaster from a non-commercial FM station asked Doyle when stations such as his might get relief from interference from such “Franken-stations.” Channel 6 is immediately adjacent to the reserved non-commercial section of the FM band, beginning at 88.1 MHz. The LPTV stations pitching their audio as a radio station generally brand themselves as being at 87.9.

“I am persuaded that these stations cannot possibly be operating in technical compliance with the television technical rules,” Doyle said. He also questioned how they could comply with their public service and other requirements. Doyle wants them shut down and is delivering that message to the people at the FCC responsible for LPTV licensing.

Of course, such operations will have to stop operating as analog FM radio stations when the FCC requires all LPTV stations to go digital, just as all full-power TV stations have already done. But Doyle told the Radio Show audience he believes the problem with the 87.9 stations will be resolved before that time.

RBR-TVBR observation: To the best of our knowledge, none of the licensees of these LPTV “Franken-stations” are doing the radio programming themselves, but rather are leasing them to other parties. However, any FCC fines will be the responsibility of the licensee." -RBR-TVBR

Licensed NCE broadcasters at 88.1 have been complaining of Channel 6 and 87.9 MHZ interference for decades. It would seem by these comments, that era may be coming to an end. I, personally, would not want to be a Part 15 FM that gets a complaint from one of the licensed stations at 88.1. -Something about throwing away the key. I'm just sayin'.....

I thought those "Franken-Stations" called themselves 87.7
not 87.9

Maybe the FCC should just go ahead and give up 87.5-87.9 and give it to the AM's or low-powers.

Found here:

NOUO - Case Number: EB-10-CG-0388

which includes the notation

"Operation of a broadcast station on 87.9 MHz, however, is not authorized at any field strength level. See 47 C.F.R. S:15.209(a). Thus, this station is operating in violation of 47 U.S.C. S: 301."

Then there was the NOUO with the measured field strength of almost 180,000 uV/M - don't think that was a Ramsey with a dipole...

As a follow up, I started listening in to 87.9 when driving around town and I picked up quite a few in-car transmitters for adapting portable audio devices to vehicle radios.

Kind of like the old DXing days 🙂