I got my Novice license in late 1955 and had an NC88 receiver in my dorm
room at the Iowa Braille and Sight-Saving School.  By the fall of 1956, ten
meters opened up like gangbusters.  

Diathermy machines, when you heard them, were a loud broadbanded buzzing
signal whose frequency wasn't stable.  27 MHz, like 13.56 MHz and some
higher bands, was an "industrial, scientific and medical" band, where other
occupants could expect some QRM from unlicensed stations.  The band was
changed to Class D Citizens Radio Service in the United States sometime
during 1958.

While 11 meters was a ham band, because it was considered a "junk" band, you
were allowed to run A0 emission, which meant unmodulated carrier.  This
meant that you could operate in a duplex mode, leaving your transmitter
running while you listened to other stations on a different band.  I used to
enjoy listening to a W1 who would call CQ DX toward Europe on 11 meters,
then leave his transmitter on while he tuned his receiver across the ten
meter "foreign phone band" from 28.5 MC and lower.  He could always hear a
lot more with his beam than I could with dipoles and my NC88.  It was a
blast while it lasted.  BTW, this was all A M.  Ten was almost the last band
to have any SSB activity; I heard my first SSB stations on 10 in about 1963,
I think.
73,
Lloyd Rasmussen, W3IUU, ex-K0DDA, Kensington, Maryland
Home:  http://lras.home.sprynet.com
Work:  http://www.loc.gov/nls
 

> -----Original Message-----
> From: For blind ham radio operators [mailto:[log in to unmask]]
> On Behalf Of Mike Duke, K5XU
> Sent: Tuesday, October 19, 2010 6:58 PM
> To: [log in to unmask]
> Subject: When are the Bands Open Part Next
> 
> I never had access to the AM pagers on 35 megacycles, but I found
> several just below 10 meters, probably around 27.8 or 27.9 MC.
> 
> Maybe Callon can shed some light on this bit of history too. Until
> sometime in the late 1960's or maybe the early 70's, the Canadian
> Citizens Band was only 19 channels. Their channel 1 was the same as
> channel 4 in the US, which was 27.005. Until additional CB channels
> were added for Canada, the portion of 11 meters from 27.000 down to at
> least channel 1, 26.965, perhaps a bit lower, was still a ham band
> north of the border, and in most of the rest of the world.
> 
> I remember hearing a guy named Fred, VE5LR, on 10 meters a lot when I
> was an SWL from 1966 until I was licensed in 1969. I think he was
> disabled in some way, but I'm not absolutely sure about that. Anyway,
> more than once Fred would be talking with a DX station from across one
> pond or the other, and would say, "Let's QSY to 11 meters." Away they
> would go. I would then fire up my 23 channel CB set to listen to them,
> and they would be right there, loud and clear, until they were walked
> on by US stations.
> 
> I talked with VE5LR once or twice on 10 meter AM after upgrading to
> general in 1970. We were both running Viking Ranger transmitters.
> 
> Now for one more bit of CB noise trivia.
> 
> Does anyone remember the remote control transmitters that lived on
> channel 23 until around 1970 or so?
> 
> I was told that some of those transmitters ran 300 watts input, and
> were used to operate elevators. Thus, each time you called for an
> elevator, or pressed a floor number, that transmitter would fire up
> with a carrier, send one or more tones, pause about 5 seconds, and
> turn off.
> 
> Needless to say, when the skip was in, channel 23 became unusable
> because of those things.
> 
> I don't recall ever hearing a diathermy machine, (perhaps misspelled)
> which also lived on 11 meters, but maybe Don Bishop and a few others
> on this list can tell us more about that noise.
> 
> I do remember a group of AM hams who camped out around 29.0 on 10
> meters who called themselves "The Displaced Diathermy Dodgers." At
> every opportunity, they would tell you that "Ham Radio went to hell
> when we lost 11 meters."
> 
> 
> Mike Duke, K5XU
> American Council of Blind Radio Amateurs