Sangean ATS-909 external antenna impedance??
 

On Sun, 03 Jan 2010 13:10:17 -0600, Lostgallifreyan
wrote:

Did the bucket brigade
lead directly to the switched capacitor filter?

Same thing if I read you correctly.

73's
Richard Clark, KB7QHC

Sangean ATS-909 external antenna impedance??
 

Lostgallifreyan wrote in
:

It was
the subject of my first class that I taught in the Navy

Curious... You might have experiences that give useful insight into something
I'm discussing in another group, some off-the-wall topic I entered into
during a quiet new-year's moment in alt.lasers... I can accept that you might
not want to get into that at all once you see it but if you do I welcome the
input because as I state there, one issue is to find helpful signals rather
than the noise such discussions usually provoke. But it might be a lengthy
misdirection if you're busy so I won't push the point. But I will say now
that my dad was a naval officer when he was younger and he SAW that thing I
described right there with me, and he had no clue either. I just keep
thinking that some people in the navy might be better able to explain it than
most, especially if they have a strong science or engineering background.

Sangean ATS-909 external antenna impedance??
 

Richard Clark wrote in
:

On Sun, 03 Jan 2010 13:10:17 -0600, Lostgallifreyan
wrote:

Did the bucket brigade
lead directly to the switched capacitor filter?

Same thing if I read you correctly.

73's
Richard Clark, KB7QHC


Interesting. I guess fabrication accuracy and timing accuracy improvements
led to its sharp cutoff and improved ability. I'm using one in some project I
have on hold, a way to get pitched sounds to control MIDI signals for musical
instrument control. I'll stop that line of thought there though, I'm not
ready to go into that project for a while.

Sangean ATS-909 external antenna impedance??
 

On Sun, 03 Jan 2010 13:07:26 -0600, Lostgallifreyan
wrote:

If you look at that PDF you'll see the 15' whip antenna is directly connected
to ground through 80 turns of wire on a ferrite toroid. I might add a spark
gap in parallel as that wire is not a high current path. So long as it is
much more likely to go to ground rather than along the line in to the house,
I'll have done what I'm supposed to do. The trouble would only exist (other
than unpreventable natural excesses) if it were evident that I had not done
this.

Yes, it is a grounded design. The folded monopole is simpler, however
and you can deal with matching identically. 80 turns of wire on a
ferrite toroid is going to test the limits of self-resonance, poor Q,
and efficiency across so large a span of frequency.

Well, a ground rod isn't going to cost much, and making and breaking
connections to it is one of the easiest and cheapest things I'll be able to
do, so I'll test that empirically when I'm ready. I won't try to predict it
now. Whenever I find some new ground noise problem in anything I do here, I
usually manage to isolate it and solve it acceptably within an hour or less,
so I'll trust my chances. Usually the purpose hasn't been for RF, but quite
often the sources did involve RF too so my instincts might help me more than
my knowledge.

Sounds like a lot of faith and work that will eventually require more
investment in faith and work. A shallow buried radial system would
puncture these superstitions.

Let's revisit one of your statements above:
balanced microphone cable with a screen grounded at one end
Which end? Any choice stands an equal chance of being the wrong
choice.


Well, I did think of that. :) And I didn't state it because I didn't know for
sure.

That's why I tossed that hand grenade into the mix.

As I imagine that local RF couplings from various digital devices might
place small currents on the local ground, I imagine that grounding a shield
at the remote ground makes sense.

It does, but that isn't the complete solution if you don't choke the
feedline. Again, ground is not found in the rod you drive into the
earth (which, by the way, will take years to "cure" to the ground
resistance you hope to achieve).

Doesn't matter to me though. It's far
easier and faster to experiment than to try to predict because there are only
two ways to try.

This is about experience. You will find (and I have found) damn
little reference to grounding by connection to the earth. It has
taken me years to accumulate these rare references. They have been
topics of discussion here (use google to search the archives).

Dallas Lankford directly states that no shield is even
required, and I doubt he'd have said that if he couldn't demonstrate it, and
as that line is a two-wire loop that has no direct contact with anything, it
should reject any common mode noise that hits it.

Many people make direct statements (hard not to in this environment
that relies on textual postings). You need to find a better source of
study material as it relates to Common Mode. Twin line suffers it
equally. Again, all such discussion arrives through where the source
and load are, not in the line between.

Even in audio this matters
because the same method is used to reject RF pickup on audio lines. I think
some people persist in baluns instead of op-amp common mode rejection specs
for this reason, despite the chances of modest distortion in audio bands from
the transformers used. Not entirely relevant but it illustrates how people
can find themselves choosing between two less-than-ideal circumstances for
best effect.

You are confusing topics here. BalUns and what are properly chokes
are not always the same, although their discussion is often co-mingled
to considerable misunderstanding. BalUns are NOT transformers as you
might imagine from the point of view of AF. It is regrettable that
BalUns are called transformers, as their full nomenclature is
Transmission Line Transformer - meaning the transform of Z by
transmission lines that have their ends isolated through choking
action.

Lest that sound too obtuse: The best BalUns do not operate through
magnetic flux linkage. You are not in Kansas anymore.

I understand that noise context matters for a real attempt to plan for it,
but that's far more difficult that presenting the basic antenna scheme.

Hence the novelty of individual threads. Noise arrives in the same
manner as RF - it is indistinguishable until you put on your
headphones. Noise is what arrives between your ears.

In regards to this last epithet, I noticed that Lankford wrote a piece
about quad detectors. I first designed one 40 years ago and the
critical component missing in Lankford's discussion (and probably from
many such discussions surrounding this method of detection) is that
the two channel output of a phase quadrature detector is meant to
drive STEREO headphones so that the last step of detection is found in
the brain's capacity to differentiate noise from signal.

73's
Richard Clark, KB7QHC

Sangean ATS-909 external antenna impedance??
 

On Sun, 03 Jan 2010 13:25:30 -0600, Lostgallifreyan
wrote:

Lostgallifreyan wrote in
:

It was
the subject of my first class that I taught in the Navy

Curious... You might have experiences that give useful insight into something
I'm discussing in another group, some off-the-wall topic I entered into
during a quiet new-year's moment in alt.lasers... I can accept that you might
not want to get into that at all once you see it but if you do I welcome the
input because as I state there, one issue is to find helpful signals rather
than the noise such discussions usually provoke. But it might be a lengthy
misdirection if you're busy so I won't push the point. But I will say now
that my dad was a naval officer when he was younger and he SAW that thing I
described right there with me, and he had no clue either. I just keep
thinking that some people in the navy might be better able to explain it than
most, especially if they have a strong science or engineering background.

Well, I'm not sure what you are trying to bring up here. As far as
I'm concerned, any topic is open for discussion. If others fume and
fulminate about this being an antenna group, I can easily turn the
discussion into one that is antenna specific.

What did your Dad see? (We used to joke that after the Pueblo
incident they put Marine guards outside of the radio shack for
security. If the ship was in danger of being boarded they were to
step into the shack and shoot the operators. Then I went into the
submarine navy, aboard a tender, the USS Holland, AS-32. We had an
escort sub that followed us at sea - to sink us if the Ruskies got too
close. Ah, the humor of those days.)

73's
Richard Clark, KB7QHC

Sangean ATS-909 external antenna impedance??
 

Richard Clark wrote in
:

On Sun, 03 Jan 2010 13:07:26 -0600, Lostgallifreyan
wrote:

If you look at that PDF you'll see the 15' whip antenna is directly
connected to ground through 80 turns of wire on a ferrite toroid. I
might add a spark gap in parallel as that wire is not a high current
path. So long as it is much more likely to go to ground rather than
along the line in to the house, I'll have done what I'm supposed to do.
The trouble would only exist (other than unpreventable natural excesses)
if it were evident that I had not done this.

Yes, it is a grounded design. The folded monopole is simpler, however
and you can deal with matching identically. 80 turns of wire on a
ferrite toroid is going to test the limits of self-resonance, poor Q,
and efficiency across so large a span of frequency.


Ok, I'll definitely extend reaserch to cover folded monopoles. (Another
curious term given that there has to be some kind of polarity there, but
never mind..) I'll be making by own transformers and housings so I don't mind
plenty of messing around with those.

Sounds like a lot of faith and work that will eventually require more
investment in faith and work. A shallow buried radial system would
puncture these superstitions.


The yard out there is partially covered by most of the trunk of a large
felled lime tree, along with lots of branch logs, as part of an effort to
retain nutrients on land that is part of a limited strategy to preserve
wildlife in an urban district. Burying anything out there is harder work than
sinking a ground rod. :) I think I'm going to have to take my chances.

Let's revisit one of your statements above:
balanced microphone cable with a screen grounded at one end
Which end? Any choice stands an equal chance of being the wrong
choice.


Well, I did think of that. :) And I didn't state it because I didn't
know for sure.

That's why I tossed that hand grenade into the mix.

As I imagine that local RF couplings from various digital devices might
place small currents on the local ground, I imagine that grounding a
shield at the remote ground makes sense.

It does, but that isn't the complete solution if you don't choke the
feedline. Again, ground is not found in the rod you drive into the
earth (which, by the way, will take years to "cure" to the ground
resistance you hope to achieve).


Even if I add a little salt water or dilute acid to accelerate that? This is
something I've been considering.. By choking the feedline, do you mean
placing ferrite slugs round it like those used on VDU cables? That's
something else that will be cheap and easy to test empirically.

Doesn't matter to me though. It's far
easier and faster to experiment than to try to predict because there are
only two ways to try.

This is about experience. You will find (and I have found) damn
little reference to grounding by connection to the earth. It has
taken me years to accumulate these rare references. They have been
topics of discussion here (use google to search the archives).


I'll do that. I gravited to Usenet for exactly this reason, I already
collected a few rare sources of info this way in other matters. A lot of the
best stuff is in web archives of usenet posts. (Although for audio I found a
single magazine called Sound On Sound to deal with it efficiently. Not RF,
but it's not exactly far removed technology). I think a lot of good
references just never reached the net, except via postings by people who have
read them. or if they have, they're in university archives I can't reach
anyway.

Dallas Lankford directly states that no shield is even
required, and I doubt he'd have said that if he couldn't demonstrate it,
and as that line is a two-wire loop that has no direct contact with
anything, it should reject any common mode noise that hits it.

Many people make direct statements (hard not to in this environment
that relies on textual postings). You need to find a better source of
study material as it relates to Common Mode. Twin line suffers it
equally. Again, all such discussion arrives through where the source
and load are, not in the line between.


There looks like one difference. Any signal hitting a coax screen if used in
this scheme will have a corresponding return current in the core wire, but if
there is any frequency dependent effect based on the nature of the coax
braid's dimensions or in the difference between that and those of the core
wire, then complexites beyond my ken might result (and maybe just as likely
be insignificant). The equality of nature in each half of a twin wire appeals
to me, so long as it actually works. Should be cheap and easy to test that
one...

Even in audio this matters
because the same method is used to reject RF pickup on audio lines. I
think some people persist in baluns instead of op-amp common mode
rejection specs for this reason, despite the chances of modest
distortion in audio bands from the transformers used. Not entirely
relevant but it illustrates how people can find themselves choosing
between two less-than-ideal circumstances for best effect.

You are confusing topics here. BalUns and what are properly chokes
are not always the same, although their discussion is often co-mingled
to considerable misunderstanding. BalUns are NOT transformers as you
might imagine from the point of view of AF. It is regrettable that
BalUns are called transformers, as their full nomenclature is
Transmission Line Transformer - meaning the transform of Z by
transmission lines that have their ends isolated through choking
action.


Very likely I am missing plenty. Thing is, I see an unbalanced antenna-to-
ground on one winding and an isolated and balanced line that loops back on
itself carrying induced current from the other. It seems to me that balun and
transformer are terms that apply equally there. In other words, it appears
that the distinctions are neatly avoided while I am directed to exploit the
common nature of the thing being used. Once I see if it works my interest
will grow and I'll explore it further.

Lest that sound too obtuse: The best BalUns do not operate through
magnetic flux linkage. You are not in Kansas anymore.

I understand that noise context matters for a real attempt to plan for
it, but that's far more difficult that presenting the basic antenna
scheme.

Hence the novelty of individual threads. Noise arrives in the same
manner as RF - it is indistinguishable until you put on your
headphones. Noise is what arrives between your ears.


That's actually the single best argument for empirical testing. :) Something
else that audio work has told me many times...

In regards to this last epithet, I noticed that Lankford wrote a piece
about quad detectors. I first designed one 40 years ago and the
critical component missing in Lankford's discussion (and probably from
many such discussions surrounding this method of detection) is that
the two channel output of a phase quadrature detector is meant to
drive STEREO headphones so that the last step of detection is found in
the brain's capacity to differentiate noise from signal.


That's interesting. I've considered exploiting that idea before now. Not in
much detail, just in principle because I've heard sounds that needed this to
resolve them.

Sangean ATS-909 external antenna impedance??
 

Richard Clark wrote in
:

On Sun, 03 Jan 2010 13:25:30 -0600, Lostgallifreyan
wrote:

Lostgallifreyan wrote in
5:

It was
the subject of my first class that I taught in the Navy

Curious... You might have experiences that give useful insight into
something I'm discussing in another group, some off-the-wall topic I
entered into during a quiet new-year's moment in alt.lasers... I can
accept that you might not want to get into that at all once you see it
but if you do I welcome the input because as I state there, one issue is
to find helpful signals rather than the noise such discussions usually
provoke. But it might be a lengthy misdirection if you're busy so I
won't push the point. But I will say now that my dad was a naval officer
when he was younger and he SAW that thing I described right there with
me, and he had no clue either. I just keep thinking that some people in
the navy might be better able to explain it than most, especially if
they have a strong science or engineering background.

Well, I'm not sure what you are trying to bring up here. As far as
I'm concerned, any topic is open for discussion. If others fume and
fulminate about this being an antenna group, I can easily turn the
discussion into one that is antenna specific.

What did your Dad see? (We used to joke that after the Pueblo
incident they put Marine guards outside of the radio shack for
security. If the ship was in danger of being boarded they were to
step into the shack and shoot the operators. Then I went into the
submarine navy, aboard a tender, the USS Holland, AS-32. We had an
escort sub that followed us at sea - to sink us if the Ruskies got too
close. Ah, the humor of those days.)

73's
Richard Clark, KB7QHC


Antennas? In this case you'd have your work cut out for you. :) Wasn't just
him who saw it. I saw it first, for an hour and a half, before I decided it
would stick around long enough to justify getting my parents to look at it
too. I'm a bit embarrssed to mention it here other than to point to it there,
but it was two crossed 'beams' in the sky. Trust me, it's hell of a
misdirection if you're not up for it, you'd have to go to alt.lasers and take
a shufti at the posts there.. But I agree, opening it to discussion is good.
I spend about 99.999999% of the time keeping it to myself but I'm getting too
old to want to leave it as unresolved as it is now. If it has to be, ok, but
I ought to try..

Submarines? Those scare me. I never had to go in one, I don't know if
claustrophobia would have beaten me. I have found the sound of water passing
all round me as I waited for sleep in a crew cabin below decks in a ship's
bow to be one of the most comforting sounds I ever knew, so maybe I wouldn't
have.

Sangean ATS-909 external antenna impedance??
 

On Sun, 03 Jan 2010 14:19:05 -0600, Lostgallifreyan
wrote:

Burying anything out there is harder work than
sinking a ground rod. :) I think I'm going to have to take my chances.

Consider the significance of "shallow" inches, not feet; and sometimes
barely beneath the surface if you have to. If you don't have to (no
trip hazards to worry about) on the surface is equally suitable. You
don't need bare wire, but you can use it - it doesn't matter.

Radials need only be as long as your vertical is high. 16 to a couple
of dozen are sufficient.

Even if I add a little salt water or dilute acid to accelerate that? This is
something I've been considering..

Don't go there. Curing takes years and is an issue of soil
compaction.

By choking the feedline, do you mean
placing ferrite slugs round it like those used on VDU cables? That's
something else that will be cheap and easy to test empirically.

That is exactly one very good solution. You need to research the
appropriate ferrite mix which is frequency specific when we are
talking about huge swaths of LF to HF coverage.

There looks like one difference. Any signal hitting a coax screen if used in
this scheme will have a corresponding return current in the core wire,

This one statement exposes a very large problem in understanding about
the physics of coaxial cable.

The equality of nature in each half of a twin wire appeals
to me, so long as it actually works. Should be cheap and easy to test that
one...

Actually, it is harder than you might imagine at first glance. Yes,
the methods are simple, but getting past preconceived notions is the
single greatest hurdle. Many engineers are ill suited to the task.

73's
Richard Clark, KB7QHC

Sangean ATS-909 external antenna impedance??
 

Richard Clark wrote in
:

On Sun, 03 Jan 2010 14:19:05 -0600, Lostgallifreyan
wrote:

Burying anything out there is harder work than
sinking a ground rod. :) I think I'm going to have to take my chances.

Consider the significance of "shallow" inches, not feet; and sometimes
barely beneath the surface if you have to. If you don't have to (no
trip hazards to worry about) on the surface is equally suitable. You
don't need bare wire, but you can use it - it doesn't matter.

Radials need only be as long as your vertical is high. 16 to a couple
of dozen are sufficient.


I won't have scope for that much but I can certainly run a few longer ones on
unpaved ground alongside walls if that helps. I've thought about doing that
anyway.

Even if I add a little salt water or dilute acid to accelerate that?
This is something I've been considering..

Don't go there. Curing takes years and is an issue of soil
compaction.


Ok. I intend to use one of those drills that have a hammer action without
runing, to push the rod in. If I find a rod with a slight taper that would
help.

By choking the feedline, do you mean
placing ferrite slugs round it like those used on VDU cables? That's
something else that will be cheap and easy to test empirically.

That is exactly one very good solution. You need to research the
appropriate ferrite mix which is frequency specific when we are
talking about huge swaths of LF to HF coverage.


I will, I've already been looking into that so I don't have to blindly hunt
for some toroid by make and model number.. I notice the US has much easier
access to high permeability materials than the UK does, but no idea why this
is so. I saved a couple of PDF's with tables of frequency ranges vs materials
used.

There looks like one difference. Any signal hitting a coax screen if
used in this scheme will have a corresponding return current in the core
wire,

This one statement exposes a very large problem in understanding about
the physics of coaxial cable.

The equality of nature in each half of a twin wire appeals
to me, so long as it actually works. Should be cheap and easy to test
that one...

Actually, it is harder than you might imagine at first glance. Yes,
the methods are simple, but getting past preconceived notions is the
single greatest hurdle. Many engineers are ill suited to the task.


Try me. All it needs is a clear statement that I can relate to something
I've already experienced. I'm well used to being cautious about what I learn.
Unless it's as tough as atomic physics, it should be digestible, even if
slowly. And I won't be able to taste it till tomorrow... got to sleep soon.
Thanks for this, it encourages me to take the time when others do.

73's
Richard Clark, KB7QHC

Sangean ATS-909 external antenna impedance??
 

On Sun, 03 Jan 2010 15:35:54 -0600, Lostgallifreyan
wrote:

Actually, it is harder than you might imagine at first glance. Yes,
the methods are simple, but getting past preconceived notions is the
single greatest hurdle. Many engineers are ill suited to the task.


Try me. All it needs is a clear statement that I can relate to something
I've already experienced. I'm well used to being cautious about what I learn.
Unless it's as tough as atomic physics, it should be digestible, even if
slowly. And I won't be able to taste it till tomorrow... got to sleep soon.
Thanks for this, it encourages me to take the time when others do.

We shall proceed with a object lesson found in Fig. 5 of:
http://www.kongsfjord.no/dl/Amplifie...Amplifiers.pdf

Consider that this is described in the right side of Fig. 2 with all
the expectations of being "balanced." It is not. Even on viewing the
rough block diagram of Fig. 2 it is apparent in this lack of balance.
Fig. 5 and photos do nothing but support this shortfall.

At first glance, it seems as though these materials are classic text
book stuff that begs to be accepted as "balanced;" reality intrudes in
that RF (far more so than AF) finds interwinding capacitance is not
distributed equally for T2 and T3 primaries to secondaries.

The input/output windings are easily as unbalanced as one could find.
"Of Course! a protest might start. T2 is meant to support an
unbalanced input." However, a closer glance would admit that the
capacitive coupling from the top of T2 input to the top of T2 output
is NOT the same as the capacitive coupling from the bottom of T2 input
to the bottom of T2 output (irrespective of the implied ground
connecting, or not, to the middle of the T2 output winding).

The top Basic Amp is thus presented with a higher potential than the
lower Basic Amp. One might protest that this does not matter as T3
uncouples the two to present a new output through it to the 50 Ohm
output. My rejoinder would be "What practical advantage is then found
in the symmetry of upper/lower Basic Amps?" I would then point out
that the Common Modality present in the input, is amplified in the
upper half and finds its way through the system.

The solution involves complex winding taps with capacitors tied from
them to common to enforce a balance. This is not practiced
(obviously) in the object lesson presented at the page referenced
above.

A protest might erupt that this example's capacitive asymmetry only
admits of a very small imbalance. I would respond that Common
Modalities may easily support considerable currents/voltages that when
reduced through divider action are easily in excess of small signals
of interest. The Basic Amp input Z is 50 Ohms; an imbalance in the
interwinding coupling capacitance amounting to 50 KOhms will add 1000
microvolts for any 1V CM signal on the left. At 1MHz, this 50 KOhms
would be a capacitance imbalance of 3 pF. Looking at the wire
dressing of the coils in the photo would suggest 3 times this easily
(and no attention has been paid to this at all). Now extrapolate to
the 31 Meter band.... Could your AGC tolerate the local AM station's
10,000 microvolt leakage sitting on top of Radio Burundi's signal?

Grounding and shielding is not a simple topic although it is deceptive
in appearance.

73's
Richard Clark, KB7QHC