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Where Did You Hear CHLO on 680 AND 1570?

S

Schroedingers Cat

It reminded me when we are talking about DXing on 730 kHz that the Mexican Clear Channels 730, 800, 900, 1050, 1220, and 1570 used to be very restricted in the United States. There was a special agreement to have one fulltime 50 kW station on 1050 in New York City and a fulltime 50 kW station on 1220 in the Detroit Area, which ended up in Cleveland. There were NO other stations operating on those frequencies at night. Daytime was also restricted. There were no powers between 1000 watts and 5000 watts, and daytime only stations were generally limited to 1000 watts unless they were far from either the Canadian or Mexican border, in which case they could apply for, but apparently not always granted, a daytime power of 5000 watts. However, no such restrictions were present in Canada on these frequencies.

CHLO St. Thomas was originally on 680 kHz with 1000 watts with a four tower array day and night. Then a low power station was allowed in Toronto on 680, CHFI, which became CFTR. In order to upgrade CHFI, eventually to 50000 watts day and night, it was necessary to move CHLO and a US station in New York. CHLO moved to 1570 with 10000 watts, a frequency which had been previously used by CFPL London.

CHLO used to be heard well in Southeastern Michigan on 680, as it had a significant lobe to the West. When they moved to 1570, they could only be heard at night. Since there were no stations in the US on 1570 at night, CHLO could be heard far and wide in the US at night. In 1970, I heard it in Gatlinburg, TN. It was the only station I could hear from my general home area at night besides WJR, though I would be surprised if CKLW wasn't heard occasionally. I didn't know enough about their patterns then to know that I should have tried for WXYZ 1270, which went South just as well as North with their two tower 5000 watt pattern.

Where did you seasoned DXers hear CHLO on 680 and 1570?
 
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Broadcasting Yearbook shows the switch was made in 1970. (Thanks David Gleason)

I recall logging CHLO during my "golden" years of DX...1958 - 1964. They were on 680 at the time. Can't confirm because a well meaning relative pitched my DX log. My location would have been either Indianapolis, or Lake Wawasee in Northern Indiana.

First heard CHLO on 1570 in 1989. CHLO was battling it out with CFOR/Orillia ON.
 
I only remember CHLO on 1570. It was one of the stronger skywave signals at Higgins Lake at night. I think I also heard them in Midland....but thats a while ago! There is a 1570 at Flint. I cannot remember if it had any beats that would have been caused by a co-channel signal.


I was surprised years later to find that CHLO was "only" 10kW. But it had a very substantial ERP in the main lobe which hit Northern Michigan nicely.
 
The border was very well protected. Even in Port Huron, there was no noticeable interference to 1570 from Flint in the daytime. None of the 1570s were on the air at night until the 1980s. Then they were generally limited to 500 watts at night under the treaty with Mexico, along with stations on 730, 800, 900, 1050, and 1220. In later years, there was spurious skywave radiation from CHLO in the 1650 to 1700 kHz region, before there were any expanded band stations.
 
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I don't remember CHLO on 1570. Before 1970, I didn't have a radio capable of nulling WMAQ (670) when I was at home near where I live now. During my college years in Iowa at the end of the decade, 680 at night was usually some combination of KFEQ, KBAT, CJOB, and even sometimes KNBR. Once CHLO moved to 1570 it was at first an occasional pest for XERF. Then later, CHLO became more common as XERF's apparent transmitter issues diminished their coverage. CFOR also was a somewhat frequent visitor, although not as common as CHLO.
 
The history of CHLO on 680 said there was an intense signal over counties including Lambton, Kent, and Essex. That would indicate that the pattern had either a major or large minor lobe to the West. This is surprising, since they would be required to protect KNBR San Francisco's 0.5 mV/m 50% Skywave contour to no more than a 25 uV/m signal. With the old skywave curves used at that time and even now in the treaty, KNBR would be protected to 750 miles out. That doesn't leave much possibility for a 1 U3 signal that goes West with a 4 tower parallelogram. I wouldn't be surprised if it was a minor lobe given the conductivity in that region, and that the major lobe went North. Bill Dulmage had a map somewhere online, but substantial parts of it were obscured, as I recall in Ohio, Pennsylvania and New York, by text boxes on the coverage map, so you could not reverse engineer the pattern from the nulls and lobes.
 
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