Historical Choice of Frequencies on 40/43 Meters?

[radioartisan]

I recently got back into listening to pirate radio stations after a ~20 year hiatus.  I remember back in the late 80s and the 90s stations tended to be above the 40 meter amateur band, with 7415 being a popular frequency, if I recall correctly.  These days stations are below the 40 meter amateur band, in the 6900-6990 range.  Anyone know why this move happened?  Perhaps there less congestion than above the 40 meter amateur band?

[Shortwave_Listener]

7415 was licensed to WBCQ for a while, which made the frequency no longer useable for pirates. Later that whole band was added to the 41 meter broadcast band, so the move was made to 43 meters. You will also hear 73 meters (4185) this time of year, this band has been used in the last few years when 43 meters goes long.

[ChrisSmolinski]

Yes, most of the moves were due to interference from other stations. As the 41 meter band filled up with more SWBC stations, pirates moved below the 40 meter band.

6955 was quite popular at first. If I recall, there was a Bolivian SWBC station that caused QRM there, hence the move to 6925.

Back then, it was rare to have more than one pirate on at the same time, so only one frequency was often used. Now of course with all the activity, multiple frequencies are used, and the combination of SDRs and the internet makes it easy for stations on "oddball" frequencies to get logged, and listened to by others.

[John Poet]

Oddly enough, TCS first broadcast back in 1982 was on 6965 kHz AM, from the VFO of the original Knight T-150 transmitter.  I knew enough to stay out of the ham bands, but had no recent pirate loggings for hints on active frequencies. 

After a phone chat with Darren Leno, founder of the now-defunct  "A.C.E." North American shortwave pirate listeners club which had only been running for a month or two, he convinced me to instead broadcast around 7425 kHz, which was THE pirate frequency in North America at that time, and through 1984.  It must have been some time after that when 7415 kHz came into broad use for pirates.

[Charlie_Dont_Surf]

In the late 70s-early 80s, North American activity was scattered between 41 meters (i.e., 7300-7500 KHz) and 48 meters (i.e., 6200-6300 KHz), with occasional use of other non-typical frequencies in the tropical bands, where they were bound to be heard by a tropical-band DXer at least*, even as low as 3200 KHz, if I recall correctly. I don't recall any SSB activity in that time but I might be wrong.

As explained by others, the increased use 41 meters by powerful international broadcasters made it a tough place to operate so the shift began. I'm not completely sure why the shift away from 48 meters in North America occurred though I assume the availability of ham transmitters had something to do with it, along with the increased use of SSB, of course.

In 2024-25, with the increased utility presence, MARS/CFARS nets and the ever present peskies on 6900-7000, I can understand the increased use (though only by a small number of stations) of 6800-6900 lately. However, even in that range there is a good chance of QRM.

There are some open slots currently on 41 meters in the North American evenings (enough slots for more than just YHWH) and of course 48 meters is wide open in North America during our evenings. With the wide availability of general-coverage transmitters/transceivers (either as-built or modified after sale), the choice of frequency is less governed by the transmitter being restricted to the ham bands.

*though many of the prominent tropical-band DXers at the time were quite hostile to pirates.