In article . com,
wrote:

Telamon wrote:
In article .com,
wrote:

Telamon wrote:
In article ,
(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.

It is not a semantics argument. On the R8B you can pick the side band
to
listen to and tweak the passband.

Often if I am bother by a heterodyne or splash from an adjacent channel
I can pick the opposite sideband and the interference is GONE. The
AOR7030+ can't do that.


When you go for one sideband, you need to select a narrower filter
(technically half the bandwidth). This works just fine on the 7030+,
used with passband tuning. Also, the 7030 VFO is so steady you can pick
USB or LSB, then zero beat it. This works on shortwave, but seems to
add a flutter to AM BCB.

The Sherwood for sale on ebay may not be functional or in good working
shape as it is being sold from a drop off site rather than the user. I
have no problem passing on this sale.

Usually the passband tuning is all I need to get rid of adjacent channel
interference and the AOR7030+ and Drake R8B both have this ability. A
neat thing the AOR can do is auto notch a heterodyne tone. Additionally
the AOR will track this tone and keep it notched out if it drifts. The
Drake has a manual notch that is pretty sharp. I usually don't have to
do this because moving the passband usually solves the problem but I
have had the situation where I have splash on one side a heterodyne tone
from another station on the other sideband so both functions are needed.

The AOR 7030+ can auto tune itself to a station and maintains lock on it
without intervention and it has the auto notch feature the Drake does
not have where the Drake has the sideband selectable sync.

Every radio has its pluses and minuses and will work better in some
situations, is easier to use, or sound better than other radios.

--
Telamon
Ventura, California

I use the notch filter quite often, but unless things have changed, it
was an option on the radio. By the time you outfit a 7030 with all the
goodies, it costs much more than the Drake R8B did. I never found the
noise blanker to be all that useful on the 7030, but it might just be
me.

I bought the AOR7030+ plus with options and it cost more than the Drake
R8B.

--
Telamon
Ventura, California

craigm wrote:
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

Both methods have their limits to unwanted sideband rejection.

For the filtering method, no physical filter has infinitely steep sides, so
closer to carrier, the unwanted sideband rejection can be poor if you do
not want to also lose part of the desired sideband.

For the phasing method, the unwanted sideband rejection is based upon the
accuracy of the phasing network. The better the network, the better the
results.

So, to say one is better than the other is challenging. If you wish to say
one is better than th other, you will need to describe the two specific
implementations in great detail. This must include the characteristics of
the filters and phasing networks over the range of interest. Deetailed
measurements of unwanted sideband rejection vs. frequency would be good to
see.

craigm

One question here is how do you know the Drake is using quadrature
techniques to kill the other sideband. You may be selecting a sideband,
but again, how do you know how it is selected. I've designed Hilbert
transformers for narrow data applications. Getting a good Hilbert
transformer for voice grade isn't as easy. The sideband cancelation
will only be as good as the Hilbert transformer allows.

wrote:


craigm wrote:
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

Both methods have their limits to unwanted sideband rejection.

For the filtering method, no physical filter has infinitely steep sides,
so closer to carrier, the unwanted sideband rejection can be poor if you
do not want to also lose part of the desired sideband.

For the phasing method, the unwanted sideband rejection is based upon the
accuracy of the phasing network. The better the network, the better the
results.

So, to say one is better than the other is challenging. If you wish to
say one is better than th other, you will need to describe the two
specific implementations in great detail. This must include the
characteristics of the filters and phasing networks over the range of
interest. Deetailed measurements of unwanted sideband rejection vs.
frequency would be good to see.

craigm

One question here is how do you know the Drake is using quadrature
techniques to kill the other sideband. You may be selecting a sideband,
but again, how do you know how it is selected. I've designed Hilbert
transformers for narrow data applications. Getting a good Hilbert
transformer for voice grade isn't as easy. The sideband cancelation
will only be as good as the Hilbert transformer allows.


by looking at the schematic?

craigm wrote:

Michael Black wrote:

[...]

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


Both methods have their limits to unwanted sideband rejection.

For the filtering method, no physical filter has infinitely steep sides, so
closer to carrier, the unwanted sideband rejection can be poor if you do
not want to also lose part of the desired sideband.

For the phasing method, the unwanted sideband rejection is based upon the
accuracy of the phasing network. The better the network, the better the
results.

So, to say one is better than the other is challenging. If you wish to say
one is better than th other, you will need to describe the two specific
implementations in great detail. This must include the characteristics of
the filters and phasing networks over the range of interest. Deetailed
measurements of unwanted sideband rejection vs. frequency would be good to
see.

craigm





With modern circuitry, the phasing networks are near-perfect, with
far better effective shape factors than what one gets with even the
most expensive physical IF filters.

Additionally, a synchronous detector using its own phase shift
networks for USB or LSB interference cancellation has a 6 dB S/N
advantage over using IF filtration to cancel one sideband.

That is because the Q channel contains INTERFERENCE ONLY and
virtually NONE of the desired station's audio. The Q channel is in
an audio null for the DSB information. Therefore, the phase
cancellation works on interference only, and the full phase
reinforcement of the desired DSB audio gives you 6 dB stronger
desired audio (yes, 6, not 3, because of phase coincidence) than one
sideband alone.


With all good wishes,



--

Kevin Alfred Strom.

News: http://www.nationalvanguard.org/
The Works of R. P. Oliver: http://www.revilo-oliver.com
Personal site: http://www.kevin-strom.com

craigm ) writes:

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

Both methods have their limits to unwanted sideband rejection.

For the filtering method, no physical filter has infinitely steep sides, so
closer to carrier, the unwanted sideband rejection can be poor if you do
not want to also lose part of the desired sideband.

For the phasing method, the unwanted sideband rejection is based upon the
accuracy of the phasing network. The better the network, the better the
results.

But, when the phasing method was common, ie almost fifty years ago, they
were using a phasing network that would only be good enough. And I'm sure
when the method is used in the less expensive shortwave receivers of today,
it's for cost reasons (read simplicity and low parts count) rather than
to get improved performance.

Yes, in recent years people have done work on the phasing method that uses
more complicated phasing networks and which pay attention to detail, but
they are no longer simpler.

Note that I'm arguing the point because the poster I replied to seemed
to be comparing the two methods, and did say the phasing method offered
better unwanted sideband rejection, or at least that's the way I read it.

Michael