Re: Dual Frequency Day & Night

[dan.strassberg@att.net]

There is one station in the US at present, ethnic-
formatted WNZK, licensed to the Detroit suburb of 
Dearborn Heights, MI. WNZK operates with 1 kW-DA day and 
night. It's on 690 days and 680 nights and uses separate 
six-tower day and night arrays at the same site.

One report I've heard says that the station uses the 
Kahn Powerside modulation system--a modified single-
sideband, full-carrier modulation technique, to put most 
sideband energy below the 690-kHz daytime carrier and 
above the 680-kHz nighttime carrier. Thus--at least on 
analog-tuned radios--the claim is that listeners do not 
notice the change in frequency and do not have to retune 
their radios.

In years past, Canada had at least two such stations, 
but under Canadian rules, each "station" was licensed as 
two stations--one operating days, the other operating 
nights. One was CHIR/CHYR Leamington ON, east of 
Detroit. I forget which calls were used by day and which 
by night, but the daytime operation was on 710 with 10 
kW and the night operation was on 730 with, I believe, 1 
kW.

The other was CFGR/CFRG in the Francophone enclave of 
Gravelbourg, SK. Again, I'm unclear about which calls 
were used when, but the station was originally full-time 
on 1290. This was when Canadian Class IIIs were limited 
to 5 kW. The station applied for, was granted, and built 
a 10-kW daytime facility on the much better frequency of 
710, a US Class IB channel not then available for 
nighttime use in Canada, but continued its nighttime 
operation on 1290. For sure, that one required retuning 
of radios at sunrise and sunset.
--
dan.strassberg@att.net
617-558-4205
eFax 707-215-6367
> Do any AM stations use dual frequencies? A different one for day and night?
> 
> Is this a real thing or just something I've misheard?
> 
> --Mike
> 
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