RC,
..
You write well and are an easy read.
But a casual Shortwave Radio Program Listener would be put-off
by the tone and technical details of your replys.
..
What more can I say
except that I am a SWL
{No License Required} ~ RHF
..
..
= = = Richard Clark wrote in message
= = = . ..
On Tue, 29 Jun 2004 22:41:44 -0600, John Doty
wrote:
Consider a lamp dimmer that generates 10 mW of RFI, which rides out in
common mode on the mains, finds its way to the power cord of your
transceiver, rides out on the feedline to the antenna, and then couples
back through differential mode to your receiver input. That's not a very
efficient coupling path, so suppose it has a loss of 60 dB. You'll still
get 10 nW to the receiver. This is a lot: even if it's spread over 30
MHz, it's still 10 uV in a 6 kHz channel. That's S6 on my Drake R-8, a
very serious quantity of noise.

10 uV into 50 ohms is 2 pW, not 10 nW (E^2/R). 2 pW = -117 dBW = -87
dBm. Multiplying by 30000/6 = 5000 buckets makes 10 nW or -50 dBm.
Cancel the assumed 60 dB loss and I get +10 dBm, or 10 mW. The numbers
add up fine.

As I said, one of the two of us was being pencil-whipped. This does
nothing to change the fact that the original term has no basis in
fact. It could as easily be laid to the effects of a nuclear EMP 2000
miles away. There will always be something to blame, and that is NOT
a solution nor is it differentiable between Ham and SWL antennas.

However, if I return to the original "problem" of noise derived from
household sources; then that is also something I have closely
measured.

Across time, frequency, antennas, and known noise sources I have found
it as low as S1 for my longwire (an antenna supposedly unused by Hams)

RC - A "HAM" would in-fact use a Longwire Antenna cut for a
specific band. However, a SWL'er would simply use a "Random
Wire" Antenna to use on all bands.
..
..
to as high as S7 (for that same longwire). My loops, dipoles and
verticals hardly fell outside of this range to present any gilt-edge
design.

Just because you couldn't doesn't mean others can't.

Can't WHAT? The numbers I offer are shown of direct experience
correlatable to real world conditions and conform to 3 Sigma of SWL
conditions.

"conform to 3 Sigma of SWL conditions"
RC - How Would You Know ?
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Being correlatable they were also resolved and reduced to
that same unpowered baseline without forcing me off the grid into
darkness. My station sits with a noise flicker based upon
atmospherics and radiation borne products, not the usual household
pollution that I both describe above and eliminated through techniques
described as commonplaces in this group.

RC - Yes as a HAM you may indeed have your station near a noise
flicker based upon atmospherics and radiation borne products.

But again the average SWL'er would not go to all that effort.
To the SWL'er an 'outside' External Antenna that is built with
Low Noise design concepts puts them into the area of Strong
Signals and "Good Listening".
? Why Do More ?
..
..

There are no magic antennas and no magic rituals equal to these
commonplace practices that are offered here.

Look at the rest of
the articles on the BADX site. Taking steps to minimize common mode
coupling has worked very well for me, and many people tell me it works
for them too.

This material is NOT novel by any stretch of the imagination.
However, it is hardly fully encompassing and falls short of the entire
treatment.

The average SWL'er is not a HAM and does not require the 'entire
treatment' to get a low noise strong signal and "Good Listening".

RC - As a Licensed Amateur Operator you may be keenly interested
in the Whys and Wherefores of All-Things-Technical.

But again the average SWL'er would like to see a picture/diagram
and read a paragraph of text that they could make the decision
to build or buy the radio or antenna.
..
..
The notion that a spike in the ground solves common mode
reveals a very limited experience in the matter, and simply devolves
to the misty eyed sentimentality of "it works for me, so there is no
better way for you." Testimonial is a poor substitute for how and why
- especially when the suggested solution inevitably fails for someone.

"conform to 3 Sigma of SWL conditions"
Yes even 3 Sigma (99.73%) leaves 27 failures in 10,000.
But you forget the 9,973 success out of 10,000.
Or 997 success out of 1000.
or 99 success out of 100.

RC - Alas there are no perfect solutions to all problems
and in-fact One-Size does not Fit-All.
..
..
The common response in that situation is to sneer them away as somehow
deserving their predicament - again, with no one knowing the basis of
the problem, they can hardly help but repeat the same nostrum now
shown to fail somewhere (an anathema in religion).

You might also find the articles at http://www.qsl.net/wa1ion/

These suggestions grow more bizarre by the posting where the
correspondent offers that SWLers ignore Amateur advice as poor quality
(a remark from a noted Yahoo), and then offer proof of their own
beguiling theories through quotes from - Amateur references.

RC - If the Advice is over-the-head of the SWL'ers or
not-applicable to the SWL'ers needs; then indeed it
generally gets ignored.

And Thank for the 'noted' Yahoo comment
RC - Some would say a Yahooligan! )
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..

interesting, especially the one entitled "Another Look at Noise Reducing
Antennas". Mark's antenna designs are generally useless for
transmitting, but they make superb MWDX receiving antennas.

I cannot see how injecting the notion of uselessness is a boon for an
argument upon a physicist who can understand the notion of symmetry or
what is called in this field of study, reciprocity. If it is useless
as a transmit antenna, is it useless as a receive antenna? Of course
not, as such the injection of this comment serves no purpose other
than rhetorical noise.

"this comment serves no purpose other than rhetorical noise."
RC - That it does )
..
..

The problem with such a degraded S/N in the correspondence of ideas is
that the larger body of uninitiated SWLers come to the conclusion that
this "uselessness" is a positive boon to be sought in every antenna
design.

RC - To the 'lareger body of uininitiated SWLers'
What works... WORKS !

Our eminent Yahoo wears this badge of anti-intellectualism
as a patronizing populist.

RC - So you have promoted me from 'noted' to 'eminent'
A Yahooligan! I Am )

"anti-intellectualism as a patronizing populist"
RC - When speaking to the average SWL'er it is good to keep
things understandable; and in a form that can be put to use
without adding any unnecessary information that is not needed
to accomplish the task. {Its About Communications}
..
..

This discussion also reveals a poverty of alternative designs that
have equal or superior merits, even if devoid of transmitting
application. Those designs are widely discussed here and their merits
are weighed not in prejudicial terms but rather in technical
comparisons and their correlation to application. That is to say,
anyone can make an informed decision on the basis of these evaluations
offered here where we typical discard "testimonials" to the rubbish
heap.

RC - All that you say may fair well for technically orientated
Licensed Amateur Operators who may have several antennas.

But the majority of SWL'ers will use a single 'outside' antenna
for their Shortwave Listening needs. If one of the better choices
for a SWL'er is a Random Wire or Inverted "L" Antenna that uses
low noise design concepts; and can be built within their available
space. So... Why not start their first.
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..

A narrow null takes little power from the pattern:
you get little gain by putting that in a broad lobe. For example, an
elementary dipole has, theoretically, infinitely deep nulls yet it only
has about 2 dBi gain. Now consider a phased array: small phasing errors
have little effect on the gain, but they can have a large effect on the
null depth.

Again, this exposes a lack of experience in the matter. Those nulls
are balanced against the theoretical radiator called an isotropic
source. This is the i of the 2dBi (and in fact is actual;y higher
than that value).

Worse yet, this lack of experience further pollutes the uninitiated
SWLer's notion of this balance of ledger because no one on this earth
is ever going to experience that 2dB gain (nor the supposed sharp
nulls) - and simply due to earth being nearby (an irreconcilable fact
of life that extends out beyond 6 Sigma for the population of
listeners). A simple dipole one quarterwave above earth exhibits an
additional 3dB gain above and beyond your cited number.

RC - The classic 'bad answer' for a HAM to a SWL'er is the simple
Dipole.

Most SWL'ers do not have the available space for a not-s-simple
Dipole Antenna that will 'cover all' the Shortwave Bands and the
ability to put the Dipole up high enough for proper operation.
..
..
This goes to
show how your casually abandoned 4dB for an inverted L is so simply
recovered - through real comparisons rather than xeroxed theories.

The level of discussion is so unbalanced with myth, superstition and
hearsay that the casual SWLer seeking advice faces the problem of
sorting out the **** from the shinola. If I were to hike the dipole a
little more, it shows 8dB gain after allowing a real world loss of
1dB. To tell that same casual SWLer 4dB is no great loss gives a
spread of 10dB.

The consequence of this challenging this poor coverage of intellectual
offering is that the casual SWLer having the facts known, can in fact
choose to build a less optimal antenna, one that suits his real world
limitations, and enjoy a design that does not simply discard signal
with abandon. Alternatively, a simpler receiver can perform with an
excellent antenna as well as a box full of expensive knobs can with an
air cooled resistor.

When transmitting, you're generally interested in putting the power in
the right place, but when receiving you're often more interested in
avoiding picking up power from the wrong place. These considerations are
only weakly related.

This has been spoken too, the limitation is found in the signal and
noise being aligned along the same meridian. If there is any weak
relation it is found in the chance of distribution. The laws of
reciprocity are not violated by chance, and both Ham operator and
SWLer suffer the same odds. There is NOTHING separable here.

Who needs an efficient MW antenna?

People who transmit, of course!

And SWLers are not transmitting are they? Really, these specious
arguments do not advance any notion of this being separate issues.
There is nothing in the circularity of logic that demands poorer
transmit antenna designs are better receive antenna designs. Nearly
every beneficial description from your sources cited above lie outside
of the antenna and reside in the coupling or in the receiver. Such
commonplaces are not novel; they are not unique and special knowledge;
and they are certainly not universally applicable.

How would you undo that 4 dB loss without loss of bandwidth?

That has been responded to above. Loss of bandwidth is a chimera
suited for argument rather than operation. To say it is frequency
agile is the crowning claim for someone who is fain to turn a switch
and set a capacitor in 5 seconds.

RC - Some SWL'ers simply want an Antenna and Radio with NO 'other'
complications; for them its about Listening Enjoyment.
Others SWL'ers may want more 'gadgets' to Help them to improve
their ability to hear more signals.
..
..
This isn't rocket surgery, children
learn such techniques within minutes of explanation and faithfully
demonstrate far less loss consistently for ever after.

RC - Its a matter of personal choice and many casual SWL'ers
choose to keep it simple. A relaxing hobby that provides
interesting and enjoyable listening.
..
..

Further, the usage of a tuner solves many other ills related to noise
and front end overload.

RC - That can be true; but to many SWL'ers it is simply another
gadget that starts to make things complicated.

The argument of the 9:1 transformer to ease operation comes at
the expense of simple cheap solutions

RC - What could be more simpler and 'cheap' then a passive static
devise like a Matching Transformer ?
To paraphase what they say on the TV 'Connect It and Forget It'.
..
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- to no great benefit,
and further, to 4 dB additional loss as you describe. What
boon is to be found in that combination?

RC - For many SWL'ers it gets the job done. What works... Works!
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I find it laughable that one web site offered claims that a resonant
system is bad for your reception.

RC - If the system is resonant on one band 'only' and the SWL'er
wants an Antenna that works well on All the Bands. Then just
may be resonant is not the best answer to the needs of the SWL'er.
..
..
What a crock! This has all the logic of buying square wheels
to increase your gas mileage.

I'm hardly
boasting of martyrdom anyway: a broadband inverted L is a fine general
purpose receiving antenna.

And what distinguishes it as a poor transmitting antenna? The
inclusion of the engineering decoration of the 9:1 transformer? This
logic is destroyed by a conventional tube transmitter (the original
application suited to this design).


RC - But the modern day SWL'er is not using a 'tube' anything.

The SWLer using Inverted "L" Antenna; using a Wire Antenna Element;
coupled by a Matching Transformer; with a Grounding Point collocated
at the junction of the Antenna Element and the Coax Cable; plus
a Coax Cable Feed-in-Line to the Radio/Receiver.

Where the HAM may have used an Inverted "L" Antenna with the
Vertical (Leg) and the Horizontal (Arm) of Equal Lengths and
in 1/8WL, 1/4WL or 1/2WL sizing.
The SWL'er would most likely use an Inverted "L" Antenna with
the a 'shorter' Vertical (Leg) and a 'longer' Horizontal (Arm)
of 2X-3X the Vertical (Leg).
- An Antenna to fit and fill their available space.
- An Antenna that lends itself naturally to Low Noise Antenna
design concepts.
..
..
Once again, every issue in relation to even this point is discussed as
a commonplace in this group with simple and cheap solutions that
perform without the concurrent 4dB loss. Such a cavalier attitude of
discarding signal

RC - For the SWL Signal is not discarded to the extent that RFI/EMF
background noise is reduced by a greater amount; with an overall
improvement in the Signal-to-Noise Ratio. The Radio/Receivers AGC
Circuit then compensates for the lower signal level. The result
for the SWL'er is an improved and enjoyable Listening Experience.
Remember most SWLs are simply Broadcast Program Listeners seeking
news, information and entertainment from other countries via the
Shortwave Bands. The vast majority approach being a SWL with the
basic experience of the average Car AM/FM Radio listener. Their
beginnings are not your beginnings and their experiences are not
your experiences.
..
..
is evidence of purchasing power, not technical competence.

RC - yes, Yes. YES !
To the majority of SWL'ers it is ABOUT "Purchasing Power"
and to most SWL'ers your level of 'technical competence'
simply does not apply to their needs.
? How many SWL'ers actually read their radio's
Owner's Manual from Front-to-Back ?
..
..

I've never seen mention of this efficiency/bandwidth tradeoff in the ham
literature,


You haven't looked. Either contrived, wholly fictional, or accurately
represented, it is part of the stock in trade for selling antennas.
In this group, I would wager its discussion consumes more bandwidth
than bragging about how many QSL cards have been pasted to the wall.

Examples?

As I offered, you need to look rather than claim. They are so common
that if they escape your attention, no work on my part is going to
satisfy you.

So, the question remains:
Do you or others have any actual differentiable discussion, or is this
simply an outlet for appoligia for why it isn't worth the strain to
lift a soldering iron when you can bench press a credit card?

RC - Once Again: yes, Yes. YES !
To the majority of SWL'ers it is ABOUT "Purchasing Power"
and to most SWL'ers your level of 'technical competence'
simply does not apply to their needs.

Maybe 1/4 to 1/3 of the Shortwave Radios bought are purchased
as "Gifts' for someone. Some catch the SWL Spirit and many
simply use the radios as an AM/FM Radio with out ever getting
into Shortwave. For many of those that do catch the SWL Spirit;
an 'outside' External Antenna is their next logical "Purchace".
Far fewer get 'into' being a SWL and go about informing and
educating themselves about the technologies related to SWL.
All are SWLs be they casual, average or Expert.
..
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73's
Richard Clark, KB7QHC
..
..
What more can I say
except that I am a SWL
{No License Required} ~ RHF
..
..