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A shocking 1710 log. 1/19/2021

C

crainbebo

You will not believe what I just heard a couple minutes ago.

1710 - "KHMB" CA, Half Moon Bay; with 'Rescue Me' by Fontella Bass at 2149 PT 1/19. Went to their stream, KHMB Radio - matched!!!! According to this (Re: UNID 1710???), this part 15 station looks like they have a network of 100mw transmitters that put out an ERP of about 1 watt. QRP DX. NEW #802, and what looks like 1 watt at 665 miles. Unbelievable! This and the two Alaskans heard in October are the best logs so far this season. I have a clip I hope to upload tomorrow of the song heard in USB mode mixed with what I think is the Travis AFB California TIS (heard last year running an 'information radio' loop).
 
What a great catch! And pretty sharp engineering to feed a series of milliwatt transmitters to boost power.
 
You really have to wonder whether if this is real and not a "KLEE" hoax. I guess if you lined up a phased array of synchronous transmitters, like an interferometer DA, you could produce a field necessary to do this. Otherwise, it's like those PSSA authorizations that really aren't being used when they are heard. Theoretically possible, but statistically very unlikely. With anything short of the World Radio Historian's equipment, one should be skeptical. Do the Math.
 
1 watt of combined power using antennas which are legal for part 15 operation will not cover more than a few blocks.
 
Was this skywave or groundwave? Presumably the station was in compliance with Part 15, which means a couple hundred feet of coverage per transmitter at best. For many users Part 15 is an exercise in semantics of the rule. Just did a quick read of the rule, looks like less than 100 microvolts at about 100 feet is an overriding limit, regardless of fun and games defining antenna and ground length or total power input to final RF stage. Comment- full power AM stations do come on the market regularly, sometimes at a price within reach for an individual. just sayin...
 
Skywave, from an SDR six miles ESE in Kittitas WA (here in Ellensburg the noise level is so bad that DX is nearly impossible). "KHMB" is a licensed part 15 operation (albeit I think they are pushing it for power) and has been heard by DXers before up here. It was heard on a recent Rockworks DXpedition on the Oregon Coast by Tom Rothlisberger, K7WV, of Brier WA. Clip way down at bottom.

Rockwork DXpedition K7WV Results August 2018

Results from the August 2018 Rockwork Radio DXpedition
www.qsl.net

Makes you wonder about the other 1710 pirates the East Coasters have heard in the past, like the Big Q. Or those TIS stations that get out 300-400 miles on 1610.
 
Greg Strickland said:
Was this skywave or groundwave? Presumably the station was in compliance with Part 15, which means a couple hundred feet of coverage per transmitter at best. For many users Part 15 is an exercise in semantics of the rule. Just did a quick read of the rule, looks like less than 100 microvolts at about 100 feet is an overriding limit, regardless of fun and games defining antenna and ground length or total power input to final RF stage. Comment- full power AM stations do come on the market regularly, sometimes at a price within reach for an individual. just sayin...
Click to expand...
Well he said like 2149 PST, So 10:49pm..Skywave
 
Back in January, 1974, during the "Energy Crisis", they went to Daylight Savings Time, which put Sunrise at 9:00 AM in Michigan. The Daytimers, which at best signed on at 6:00 AM with 500 watts PSA, were understandably upset. They got the FCC to authorize 50 watts PSA for stations on Clear Channels, like WJJD 1160. One morning in 1974, I actually DID hear WJJD in Genesee County, Michigan with a believable 50 watts. It faded in and out with KSL, at very close to the same FI/signal strength. I used a long wire, with a series ferrite loop and a 365 pF variable capacitor, with the other end grounded, coupled inductively to the ferrite rod in a Sony AM/FM/Cassette recorder with a signal strength tuning meter, and also with a Westinghouse 1938 Table Radio with a 6U5 tuning indicator. WJJD and KSL were equal on alternate fade ins.
 
I underestimate determination of DXers to resolve signals! I ran a study for 1 watt at 1710 from a 90 degree tower in Half-Moon Bay. This is much greater radiation than Part 15 permits. This facility is predicted to produce 4 microvolts per meter skywave as far as Phoenix, Denver and nearly to Seattle 10 percent of the time. At Half Moon Bay groundwave nighttime interference-free contour (NIF) is 2 mv. My NIF study recognizes US, Canadian and Mexican stations. Noting all interference shown in the study is on 1700, I wonder if crainbebo was listening to 1710 on a narrow IF AM radio. With a tight IF, I think this catch is comparable to amateur radio QRP work.

​

 
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I don't know which SDR they use in Kittitas. I've driven by the building where it's located. It's a massive ham radio tower with a couple of stacked arrays, but they mostly use a Wellbrook ALA loop near the gate of a farm field. The 1710 was captured in USB mode to knock out splatter from XEPE-1700 (and possibly Iowa).
 
Not shocking but definitely interesting, especially with the transmitter network. That almost sounds like what stations in Europe and the UK do with single-frequency networks, operating several lower-powered transmitters to cover a larger geographical area.

Didn't XEPE operate (illegally) for a little while on 1710 when they were XEKTT?
 
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