Michael Black wrote:
HFguy ) writes:

Joe Analssandrini wrote:

John Plimmer wrote:

There was also a long thread on this newsgroup that claimed the AOR
7030 had
the best sync detector in the business, but I still punt the R8B as the
7030
sync was NOT sideband selectable, which is required for most good
listening.

Dear John,

Contrary to what you write, the AR7030's synchronous detection circuit
IS most definitely sideband-selectable and features double-sideband
detection as well (so does the Drake R8B). It does not feature a
"fixed" sideband selection as does the Drake R8B (or the Drake
SW8/Grundig Satellit 800), but rather a "variable" one using the
passband tuning. (You can tune the circuit this way as well on the
Drake.)

If your description (above) is technically accurate, the 7030 does not
have a 'real' sideband sync' detector because it requires using the
passband tuning to select the desired sideband in the double-sideband
mode. The sideband sync' detector on the R8B uses phase cancellation for
rejecting the unwanted sideband. This is a more effective rejection
method than using only passband tuning.


But are you arguing semantics, or outcome? Because the phasing method
of selectable sideband reception is not as good as the filter method.
A filter really knocks out the unwanted sideband, while the phasing
method tends to give far less rejection of the unwanted sideband.

Michael

A sync' detector which implements sideband rejection using the
quadrature method (phase shifting) allows the user to select one of two
signals (either sideband) which are 180-deg. out of phase. This is a
more effective way to reject the unwanted sideband of an AM signal than
using *only* passband tuning. In the case of the R8B you can reject the
unwanted sideband much better with the selectable sideband sync' than by
using just the passband tuning. It occurred to me that we may be talking
about different subjects, since you referred to phasing and filtering,
which are two methods of bandwidth selection.