KHMB 1710 AM 1105 UTC 9 Oct 2020

[ChrisSmolinski]

Listening via the Half Moon Bay CA KiwiSDR : http://69.27.184.58:8073/

A good signal, SIO 444 or so. 60s and 70s music, ID around 1713 or so.

[Dave Richards]

I'm listening to it right now (1615z), also via the Half Moon Bay Kiwi SDR, with the same SIO you were reporting. I took a trip down the California coast through Half Moon Bay a year or two ago, and was able to receive this station on a small portable (a CC Skywave SSB). With this little radio, I was able to receive a listenable signal approximately 3 miles north and south of the center of Half Moon Bay, along the coast. A signal was discernable for approximately 7 miles north and south. They are licensed under the callsign KHMV-LP, for an ERP of 100W on 100.9 FM. KHMB is actually a 3.2KW station in Hamburg, AK. Obviously, they are calling themselves KHMB for the acronym (Half Moon Bay).

This is what really puzzles me though. Given that they are radiating on 100.9FM with a licensed signal, why are they also radiating on 1710KHz, with what must surely be an unlicensed signal? Why would an operator jeopardize their license by doing that? It's a real head-scratcher for me, especially as far more people listen to FM than AM these days. If I had an FM license, I sure as heck wouldn't be radiating any unlicensed signals. However, they have been doing this for years, with apparently no problem, so I guess it has been working for them!

Please don't misinterpret this post as a disapproval of unlicensed operation. I'm quite a fan of the unlicensed HF beacons. As a kid who grew up listening to the Radio Caroline ship, the broadcast pirates have a special place in my heart. I just don't get why someone who already has a legal signal, would choose to also radiate a signal for which they have no license. Perhaps the AM signal covers some areas that the FM signal doesn't, and they don't want to leave some of their listeners in the dark?

This feller discovered them a few years ago, and was also puzzled - https://dsearls.medium.com/neighborhood-radio-in-half-moon-bay-dcee2ee9a2fc

[ChrisSmolinski]

Yes, it's puzzling that they would risk their FM license by also running an AM pirate.  Unless it's a legal Part 15 station...

According to this site, they run several transmitters on 1710 kHz, not just one, which could account for some of the range, staying within Part 15 power limits: https://www.smdailyjournal.com/news/local/making-airwaves-in-half-moon-bay/article_d7f4bbdf-66fd-5bb1-ab32-e27b61d6294f.html

But... Part 15 only goes up to 1705 kHz - so 1710 kHz would be out of the band, and subject to much lower field strength limits, vs the more generous 100 mW and a 3 meter antenna.

It is quite confusing. 

[Dave Richards]

Although I don't remember the source, I read that they have several Hamilton Rangemaster transmitters in close physical proximity. Even if they were operating within the 510 - 1705KHz band that is subject to FCC 15.219, that installation could very possibly fall outside the provisions of those rules. However, as you say, the fact that they are on 1710KHz immediately settles the question of their legality.

If they didn't have an FM license, I'd admire their swashbuckling bravado. Nevertheless, I wish them continued luck. Community radio is a great thing.