New Eton E5 gloat
 

"Joe Analssandrini" wrote in message
oups.com...
Dear "Telamon,"

I hear this "note-flattening" on music fairly frequently when listening
to music via a station whose signal is variable in strength (when
listening on my Satellit 800 with AGC set to "slow," sync circuit
"on,." using 6.0 kHz [nominal] filter or the 4.0 kHz one, and the
station's frequency set to "spot-on"). Obviously, I cannot tell others
when they will hear this effect but it is very noticeable here on the
east coast when the VOR (whose signal varies in strength) is playing
their interval signal. Try listening to that. On the Satellit 800 (and
the two Drake radios I heard - R8B and SW8), a sustained note will
appear to change frequency, "flattening" momentarilyand then returning
to its proper frequency. This happens often.

It never happens with my AOR AR7030 Plus receiver.

Best,

Joe

Perhaps I could throw my two cents into the discussion. Qualify them by
saying I have no experience with any of the radios mentioned. What I have
experimented with is add-on synch AM detectors (both homebrew hardware synch
AM and software DSP with a 455kHz/15kHz downconverter) and Radio Shack
DX-394A and DX-394B radios as tuners (OK, OK, don't tune out just yet!).
With deep, rapidly fading signals, both detectors would warble, wow, groan
when fed by the 394A. Changing the RF Gain control setting on a stable
signal had a similar effect.

Some time later, I found that the detectors did not warble, wow or groan
with the DX-394B. The difference turned out to be that the B has a buffer
between the 2nd local oscillator and the 2nd mixer whereas the A does not.
This isolates the oscillator from variable loading caused by changing the
gain of the 2nd mixer. The 2nd mixer is on the AGC line so varying signal
strength affects its gain/loading and the AGC voltage is also affected by
the RF Gain control. I added a buffer to the A and now it's as stable as the
B.

Maybe there is something similar happening to a slight extent with those
radios on which you hear slight pitch changes. Rather than a warping
upstream oscillator with gross effects as in my case, maybe the PLL
oscillator in your higher class radios is being pulled by changes in the
strength of the input signal. You mention that it is most noticeable when
you use slow AGC - that would cause the most extreme and prolonged variation
of signal strength at the input of the detector. Why not use fast AGC? That
seems to be the norm for AM reception. Do you use slow or fast AGC on the
AOR7030?

Tom

New Eton E5 gloat
 

Dear Tom,

In general, "fast" AGC is for tuning and "slow" AGC is for listening,
in order to keep the noise level more-or-less constant and to minimize,
as much as possible, fading.

Best,

Joe

New Eton E5 gloat
 

Dear John,

No one denies that the Drake R8B is one of the finest shortwave radios
ever made. I almost bought one. But, in my opinion, the AR7030 Plus,
properly configured, is superior. You disagree with me and I respect
your opinion.

But please note: you wrote I think you are wrong in assuming that the
faults you find in your Sat 800 are experienced by Drake R8B owners

John, regarding the "fault" in the design of the Drake sync circuit, I
HEARD the effect on a Drake R8B (and an SW8 as well). And please note
that I said this is not a "major" flaw, in my opinion, just a minor
annoyance. But it is there, nonetheless.

Best,

Joe.

New Eton E5 gloat
 

"Tom Holden" wrote:

Do you use slow or fast AGC on the AOR7030?

Dear Tom,

I'm almost ashamed to write this reply: for listening, I generally do
not use either "fast" OR "slow" AGC on my AR7030m Plus.

I use "medium!"

I can just hear everybody now -- "GROAN!!"

Best,

Joe

New Eton E5 gloat
 

Joe Analssandrini wrote:

Dear Tom,

In general, "fast" AGC is for tuning and "slow" AGC is for listening,
in order to keep the noise level more-or-less constant and to minimize,
as much as possible, fading.

Best,

Joe


What do you consider "Fast" or "Slow"? The receivers we built had
seven different AGC time constants, up to 10 seconds.

..01 ms
.1 ms
1 ms
..01 second
.1 second
1 second
10 seconds


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida

New Eton E5 gloat
 

"Joe Analssandrini" wrote in message
oups.com...
"Tom Holden" wrote:

Do you use slow or fast AGC on the AOR7030?

Dear Tom,

I'm almost ashamed to write this reply: for listening, I generally do
not use either "fast" OR "slow" AGC on my AR7030m Plus.

I use "medium!"

I can just hear everybody now -- "GROAN!!"

Best,

Joe

Joe, I wonder if the pitch shifting you hear on the Sat 800 or R8B might be
mitigated by using Fast AGC. That would maintain a more constant level to
the synch AM detector. Maybe you might hear pitch shifting on the 7030 if
you used Slow AGC.

While I agree with you that Fast AGC is advisable while tuning, I don't
think it is right to say that Slow AGC is always optimal for listening. I
think the choice depends on fading and interference. Rapid deep fading and
carrier-less SSB interference are best handled with Fast AGC. Slow AGC
provides lowest distortion on AM and SSB and eliminates fatiguing syllabic
pumping of background noise and interference on SSB speech. As always,
there's a tradeoff, and Medium is a compromise - as you apparently have
defaulted to on the 7030.

Of course, I have no idea what your Medium is. I tend to think of these
speeds to be on the order of:
Milliseconds Speed
tens Fast
hundreds Medium
thousands Slow

Boy, this Subject needs to be changed...E5 Gloat?

Tom

New Eton E5 gloat
 

Medium? I could be mistaken Joe,but aren't you in (in all due respect)
joking about that?
cuhulin

AGC
 

"Michael A. Terrell" wrote in message
...
What do you consider "Fast" or "Slow"? The receivers we built had
seven different AGC time constants, up to 10 seconds.

.01 ms
.1 ms
1 ms
.01 second
.1 second
1 second
10 seconds

Michael, what receivers were these and why such incredibly fast AGC?
I assume these are release speeds; what were the corresponding attack
speeds?

Tom

New Eton E5 gloat
 

Cuhulin - Medium as in 'medium' {Mind Reading}
The AGC reads his mind and . . . sets itself ;-)

a little 's l o w' on the fast (up-take) ~ RHF

AGC
 

Tom Holden wrote:

"Michael A. Terrell" wrote in message
...
What do you consider "Fast" or "Slow"? The receivers we built had
seven different AGC time constants, up to 10 seconds.

.01 ms
.1 ms
1 ms
.01 second
.1 second
1 second
10 seconds

Michael, what receivers were these and why such incredibly fast AGC?
I assume these are release speeds; what were the corresponding attack
speeds?

Tom


Microdyne 700 series, and other lines like their 1100, 1400 and 2800
series. They were telemetry systems, and they were typically used in
diversity mode so you needed the fast AGC for some applications. They
had matching integration times for attack and release. I should know, I
tested hundreds of the boards on the bench while using a time interval
counter and calculating the reciprocals on the slower ranges. :(


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida