I was interested to observe that his modulation design allows for carrier suppressed DSB or AM.
I am thinking that I may borrow that design for my mini-tube transmitter so it may do double-duty
(actually triple AM/CW/DSB). [Webmaster]
"The output of the DBM contains only the product (of audio and carrier) frequencies.
The DBM suppresses both the input signals and produces double side band suppressed carrier
(DSBSC) at its output. However, since the diodes used in the balanced modulator are not fully
matched, the output of the DBM does contain some residual carrier. This is known as carrier
leakage. By adjusting the 100 ohm preset VR2 and trimmer C7 you can null the carrier leakage.
"To receive DSB signals you need a beat frequency oscillator to reinsert the missing carrier.
If you don't have a beat frequency oscillator, or want to transmit only AM signal, adjust
preset VR2 to leak some carrier so that you can receive the signals on any ordinary radio
receiver. In AM mode 100% modulation can be attained by adjusting preset VR1 and VR2."
I also happened upon a simple conversion for the venerable military surplus BC-696
transmitter from AM to DSB. It is a readily reversible conversion. (see below)
