Many thanks for the radio history sites, Frank D. I had a lot of friends in the
BC business back when I was a teen and young adult. In the late 1950s, I was CE
for a couple years at a 1 stick, 1 kW day AM station in Arkansas.

But I always marveled at the older stuff. I'd had the pleasure of working on
some antique radios, TV, and radars. The radios were the most fun. One time I
even got to key a rotary spark gap transmitter.

Back when I belonged to the QCWA, I attended a national convention held in a
Houston hotel. When I keyed the rotary that was on display, I noticed it got
into the PA system. So I sent a welcome to the out-of-towners -- and I got a
round of applause. G

The requirement, clear up until when CW was no longer required, that shipboard
transmitters have the capability to modulate their signals with 500 Hertz, when
on 500 kHz, was an artifact of when it was needed:

1 - When phasing over from spark gap and not every vessel yet had a receiver
with regen or BFO.

2 - So, during WWII, folks at home could copy an SOS on their home receivers.
(I assume but don't recall that the low end of the receiver's BC band went down
to include 500 KC -- uh -- kHz.)

But that MCW did punch through static!

For what it's worth. The movie camera and projector I had forty years ago was
not made by Packard-Bell, as I had written before. They were made by Bell &
Howell (Bellow & Howl G).

73,
Bill, K5BY