[K6BW] Starting out in Amateur Radio

[Bill Smith]

(Purloined from QRP-L)  George, W0AV, references modulating a carrier to
produce AM.  What he is talking about is an early-days practice: modulating
a spark transmitter by putting a carbon microphone in the antenna line!

A carbon microphone varies resistance by packing carbon granules from the
effects of a (loud) voice.  Modulation of the spark-generated RF carrier was
caused directly by varying the RF signal to the antenna using the
microphone.  Needless to say, the microphones didn't last very long and
could get very hot.

Unless an alternator was used to generate the RF signal, the varying load on
the spark-gap oscillator likely generated FM as well as AM.  Both high
voltage and RF was present on the microphone, and touching same with one's
lips is described below.


Hi Gang

I enjoyed reading the info about loop modulation and "mike in series
with antenna" in a recent posting.

As a matter of fact, I used both methods at various times back in
the thirties on 160M AM (plus some FM) phone, with fairly decent results.
 I soon found that it was far safer (fewer burned spots on nose and lips)
if I connected the carbon element (from a telephone) in the ground
lead of the tuner for my "Marconi" antenna.

Back then most hams had a very limited amount of funds to spend
on  radio and resorted to some extremely  simple and inexpensive means
of communicating.

I had lots of QSO's on 160M CW  around the St. Louis area by  putting
my regenerative RX into oscillation and keying the antenna lead.  Since
the RX had no RF stage it radiated quite efficiently.

On 5M my one-tube supergen detector radiated very efficiently and
worked well as a TX.  It had the unique property of letting others know
that someone was listening!  Try to duplicate that feature with your
modern kilobuck equipment.  I worked the locals very well by
keying the RX B+ lead.

Thanks for the memories.

72 de George/W0AV

Ex-W9UXQ, W0UXQ, D4USA, D4ACD, G5AKV, EI7BX............