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Author Topic: American Truckers 27525 AM / 27.525 MHz, then 27.505 MHz 22 June 2017  (Read 268 times)

Offline R4002

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After tuning up from 26225 USB, I went past the CB band into the "uppers (27405-27855 technically, but I always look and listen between 27865 and 28305 as that's usually the "Band F" on 6-band 240-channel export radios

25615-26055 - Band A
26065-26505 - Band B
26515-26955 - Band C - "lowers"
26965-27405 - Band D - Legal CB band, or "mid band", "FCC" "CEPT" "legal 40" "middle 40" etc
27415-27855 - Band E - "uppers"
27865-28305 - Band F

Most export radios either include a 6-position switch labelled A through F, but others include a "HIGH/LOW BAND" switch plus a three position switch that's labelled A/D, B/E and C/F, further complicating things when there's no frequency counter.  My old Superstar 3900 uses this method for "band" selection. 

There's a new series of Galaxy "10 meter" radios that have a 3-position switch on the front panel.  The middle position is labelled "D", the left position labelled "C" and the right position labelled "E".  Pretty easy to figure out that once "converted" the radio will cover 26.515-27.855 MHz in those three bands.  Instead of tuning around the legal 40 channels to find a clear frequency, many truckers simply flip the band switch up or down a band, which is why AM traffic will randomly appear where there's normally SSB traffic.  To do the math for a "band", simply add or subtract 450 kHz (0.450 MHz) from the starting frequency.  Since the CB band is technically 45 channels (40 channels + 5 RC or "A" channels) at 10 kHz spacing, that equals 450 kHz.  These "skips" apply to the upper and lower bands as well.  So the truckers I was listening to on 27.525 MHz were originally on 27.075 MHz, which is CB channel 10.  This is partially why there is often less traffic heard on the "A" channels in the upper and lower bands. 

Anyway, I've been listening to two truckers chatting away for a bit on 27525 kHz - 27.525 MHz AM, with decent audio, they seem to be very close to each other going by the topic of conversation (talking about traffic, then talking about family life, its likely that they know each other personally).  The weaker of the two stations is slightly off-frequency, on about 27525.5 kHz instead of 27525.0 kHz.  Of course, with AM it makes very little difference when the frequency is clear and there's no heterodyne QRM.  I started listening at 1820 UTC, and at 1825 UTC, a Spanish-speaking station on 27.525 MHz LSB started calling CQ on top of the AM traffic.  The truckers then disappeared (possibly flipped their band switches!)

*Edit, they didn't flip their band switch, they just went down 20 kHz to 27.505 MHz AM and continued their QSO.  At 1833 they have disappered from 27505 AM as well. 
U.S. East Coast, various HF/VHF/UHF radios/scanners/receivers