Got KOA 850 Denver in Englewood FL but why did it happen?

[radioman148]

Yes. Back in the mid to late 60's there were very few stations in my zone... northern South America and southern Central America... on the air overnight that every morning was a DX opportunity. Sub-Saharan Africa was quite usual, and Brazil, Argentina and Uruguay's early sign-ons were fun to hear. But in that 1 AM to 4 AM period, North America could be quite an opportunity, with conditions often enhancing the West Coast, or the Rockies or the Plains or the East.

With only 3 local stations on the air (570, 590 and 805) every other channel was wide open.

Good memories.

And some of the DX experiences had a "remake" years later when as a consultant I'd be hired to work for some of those same stations. The best one was my first logged and verified Puerto Rican station, WITA. 500 watts on 1140. About 15 years later, I was named manager of that same station which became WQII, "11-Q".

Wish I was there for some of those DX opportunities. They must have been wonderful!

 

[Dondd]

Along the coast likely offers good DXing. I brought a radio to the beach only once. I don't recall anything special (midday).
During the day, tuning in AM while driving through the cities, like Fort Myers, Sarasota and Tampa, one hears tons of static and only the locals.
At night in Tampa, I recall only receiving the regular skywave stations, like WLW, WSB and WBT. Even the locals, like 970, were often weak and oftentimes didn't cover even their own city of licenses.

 

[Dondd]

Well, I am the author of those maps, and let me tell you why Mexico isn't included.

Mexico doesn't publish technical data on their AM radio stations. They can't even publish an accurate list of what is on the air today in their own country.

Without technical data you can't generate a pattern map.

To calculate a pattern map, you need for each tower (in database form):

Tower height
Tower spacing from #1 tower
Tower phasing from #1 tower
Tower orientation from #1 tower
Tower field data
Measured RMS at 1 km
Tower configuration (standard?, top hat?, segmented?, etc. and all physical dimensions of each section or top hat)

radio-locator and the rest are relying on the FCC database of Mexican stations which is 90% inaccurate and redundant. New owners, call sign changes, frequency changes, location changes, stations going dark, almost none of it is sent to the FCC after the initial filing. The FCC only "accumulates" Mexican radio data, they don't verify it or delete old records. Don't trust it for Mexican stations.

The current 2022 set of pattern maps seen on Medium Wave Circle have some Mexican station patterns for the first time this year. This is the result of two people (me and Steve Whitt) spending most of their summer and fall hand-correlating and cross-referencing Mexican stations to the mountain of inaccurate FCC data, to try to determine if an accurate record can be found.

Bill

Thank you for the explanation and all the work you do on those maps. They are a great help.

 

[davideduardo]

Wish I was there for some of those DX opportunities. They must have been wonderful!

The greatest fun was turning off my diplexed 570-805 kHz stations for maintenance on Sunday morning and, when dine, connecting the HQ-180 to the tower directly (not through the ATU and diplexer) to see what I could get with a couple of hundred feet of tower and a full 120 radial ground.

Second favorite was putting the 570 station on 565 and running a DX test for several hours on a Monday morning to see how many DX reports from North America were received. Those were also the only times that I was actually on the air on my own station...

 

[tvnut]

David, you're leaving us in suspense! What did you get?

 

[davideduardo]

David, you're leaving us in suspense! What did you get?

Best log was WMCA in NYC. That was interesting as WMCA in its early Top 40 days was one of my models for the 570 station in Quito, Radio Musical.

 

[gar hi]

Nice catch of KOA, vibe! Not an easy task from that far south and east in Florida.

I heard KOA in Tampa once many years ago.

I think the reason that can happen, hearing a distant station on a frequency that has other stations a lot closer, is probably the same reason WBBM can sometimes be heard here in Hawaii.