PDRUNEN ) writes:
Hi Group,

How difficult is it to put a balance modulator inside an radio that generates
AM to get Double Side Band suppressed carrier? Where can I get a circuit for a
balance modulator?

Is it possible that someone listening to a DSB with a USB receiver will not be
aware that there is another sideband on the LSB side?

Has anyone is this group ever experimented with DSB?

de KJ4UO

Most of the work on DSBsc in amateur circles is about simplicity. They aren't
using it for the benefits of having two sidebands, complete with the receiver
circuitry to take advantage of it. It is used because it's cheaper than a
complete SSB transmitter. And yes, the intent is that you use a sideband
receiver to receive it, at which point it cannot be differentiated from
an actual single sideband signal out of the transmitter.

Indeed, unless one has a a synchronous detector, it will be difficult to
properly demodulate the DSBsc signal unless one strips off the extra sideband.

With SSB, if the reinserted carrier is off a bit, you simply have output
that is somehwat shifted in the spectrum. But if you have a DSB signal,
if the carrier is not reinserted right in the middle of those two sidebands,
the two sidebands will not translate to the exact audio frequency, and
the output will be horrible. Strip off the extra sideband, either at
the transmitter or the receiver, and it's an SSB signal that the product
detector is dealing with.

So decades ago (and likely it's still the case) the reason most times
DSB transmitters appeared in ham magazines was because it was simpler
to generate DSBsc than an SSB signal. And all of the articles would
talk of how the guy at the other end would likely never notice.

As for modifying an AM transmitter, the trick is to find one with a balanced
output stage. If you've got two tubes there, likely it can be made into a
balanced modulator. And one thing that is forgotten is that it makes no
difference whether the signal is generated at a low level and amplified,
or generated at a high level. Indeed, in the latter case you eliminate the
long string of linear amplifiers.

Michael VE2BVW