[AMRadio] Winter Solstice AM Broadcast Propagation recollections


Donald Chester k4kyv at charter.net
Thu Dec 22 17:15:59 EST 2016


> But what amazed me was when I basically removed the slug
> from the antenna coil I was hearing AM Ham stations!  I later found out I
was
> listening to the 75 meter ham phone band.  I was hearing a whole bunch of
> hams talking in and around the Milwaukee area.  I was amazed at all this
and
> from that time on this
> radio was basically a 75 meter AM radio and no longer a BC set

The same thing happened to me.  I had been listening to 40m and 20m phone on
our BC receiver with one 6-18 mc short wave band.  I  had never monitored
75m because I didn't have a receiver to cover it.  I found an old 5-tube
AC/DC set in a dumpster, brought it home and tinkered with it till I got it
running.  The back masonite cover and loop antenna attached to it were
missing, so I strung up a wire antenna and attached it to one of the wires
that originally connected to the loop. Lacking the front-end selectivity
provided by the loop, images came through about as well as the fundamental
signal.  Starting about 4 PM on winter evenings, 75m phone signals began to
override anything on the broadcast band.  Evidently, over a certain portion
of the AMBC band, the second harmonic of the local oscillator would beat
with the 75m signal to produce the i.f. signal. I was introduced to the 75m
band using that  receiver, and a year or so later, picked a 1939 vintage
all-wave floor model broadcast radio that had both  longwave and shortwave
bands, and a RF stage to boot, and had a real shortwave receiver.  I later
added a BFO to  the all-wave set and used it while I was a  Novice.

At the time, 75m was almost 100% AM, and a whole lot different from what it
is now.
 



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