. The worse thing in the world is an
entrance ground that is not connected to the power mains ground.
73 Tom
_
Topband Reflector
The polyphasers are good protectors but be aware that they rely on gas
tubes for protection and their failure mode is one that leaves you
unknowingly unprotected. After so many ionizations the gas tube will fail
and won't clamp on the next strike. For a time Polyphaser made a test set
to
.
On a second more important note, lightning arrestors have very limited
value. Entrance grounding methods are probably around 90% of the cause or
cure of major damage. The only safe way to protect receivers is to
disconnect them, and that only works if the entrance system is correct.
73 Tom
broadcast band area.
http://www.w8ji.com/adsl_filter.htm
73 Tom
_
Topband Reflector
, and tie in any large metal
fences, posts, plumbing, and other potential grounds as you can. That's the
only proper way to do multiple bands.
73 Tom
_
Topband Reflector
systems.
73 Tom
_
Topband Reflector
is present on the
feedline shield.
73 Tom
_
Topband Reflector
insulation or dielectric is good enough. On 16 MHz, you could be
back to the same problem you have on 160, because base impedance would be
high again (assuming a thin element).
73 Tom
_
Topband Reflector
the
data sheet.
73 Tom
___
Stew Perry Topband Distance Challenge coming on December 29th.
, and increasing frequencies get it narrowed to an area.
I use this unit, although a wide selectivity AM portable all band receiver
would do almost as well:
http://www.w8ji.com/power_line_noise.htm
Locating noise is an application where more bandwidth is usually much
better.
73 Tom
I recall comments at a hamfest talk several years ago from Roy, W7EL, that
his two-element 40m vertical array appeared to have an unintended null in
the direction of a stand of evergreen trees not too far away from his
antenna system. While this is two octaves above 160m, it at least
mode, it is what is
outside that matters. In differential mode or transmission line mode, it is
what is on the inside of a two-conductor line that matters.
73 Tom
___
Stew Perry Topband Distance Challenge coming on December 29th.
noticeable loss, and they certainly could not be by any stretch of the
imagination resonant with such high resistivity per linear foot.
73 Tom
___
Stew Perry Topband Distance Challenge coming on December 29th.
. The outside is always the naked antenna, just like a single
unshielded conductor.
73 Tom
___
Stew Perry Topband Distance Challenge coming on December 29th.
If we want to make an antenna electrically longer through cable velocity
factor, it can't be done by the insulation slowing the wave inside the
shield.
73 Tom
___
Stew Perry Topband Distance Challenge coming on December 29th.
or remove a magical decrease.
73 Tom
___
Stew Perry Topband Distance Challenge coming on December 29th.
not be difficult to build some.
Remember the half-wave of coax makes a voltage balun, so you might as well
just save space and get more bandwidth by using a standard compact 4:1
voltage balun.
73 Tom
___
Stew Perry Topband Distance Challenge coming on December
the reference and how much better. None of this requires a lab, precise
equipment, is unreasonable, or is in the most remote way unfair. It just
requires reasonable methods.
73 Tom
___
Stew Perry Topband Distance Challenge coming on December 29th.
- Original Message -
From: ZR z...@jeremy.mv.com
This is where I think the problem is. You say:
** Since the TOA is established at almost ground zero, radials can
increase the energy at angles that would
otherwise be attenuated.
That is incorrect.
Radials, unless they radiate
Tom
___
It is undesirable to believe a proposition when there is no ground whatsoever for
supposing it is true. #8212; Bertrand Russell
forever that
radials change patterns by reducing TOA, and it will even appear in
scholarly places like eHam articles. It won't appear in peer reviewed
engineering textbooks.
73 Tom
___
It is undesirable to believe a proposition when
On 12/16/2012 8:31 AM, Tom W8JI wrote:
You likely had an antenna with 1/2 wave of wire spooled up on a short
fiberglass rod, which would never behave like a half-wave.
You are exactly right. Unfortunately, this myth dies hard.
Below is a link to a page on this topic from ANTENNAS
is. The image
antenna is a fictitious tool for estimating patterns, nothing else.
73 Tom
___
Topband reflector - topband@contesting.com
on insects, and can have zero current) that have no radiation and
no loss. :-)
73 Tom
___
Topband reflector - topband@contesting.com
strength change, measure field strength change.
73 Tom
___
It is undesirable to believe a proposition when there is no ground whatsoever for
supposing it is true. #8212; Bertrand Russell
involves more than rods.
73 Tom
___
It is undesirable to believe a proposition when there is no ground whatsoever for
supposing it is true. #8212; Bertrand Russell
, instead of misreading
Topband archives, you will see they ALSO said the screen does not when a
adequate number and length of radials is present.
Please stop the silly childish misrepresentations.
73 Tom
___
Topband reflector - topband
A Shakespere CB whip in my 66 Corvette which was advervtised for
fiberglass cars. It couldnt be heard a mile away with 4W. I added
radials from the base on the rear deck to the frame on all 4 corners and
then it worked much better. This was back in the late 70's for several
years.
CB antenna
. When
they get extremely thick the base current increases, and conduction losses
can be a significant factor.
73 Tom
___
Topband reflector - topband@contesting.com
Tom,
I think you are extrapolating one case with a particular radial length to
all vertical antenna ground systems.
The N6LF radial papers detail his NEC-4 simulations and measurements of
vertical antennas and radial systems. If I read his papers correctly base
impedance does track field
for a pesky
electric field. :-)
There are enough well-spoken salesmen selling people magic, and they don't
need our help. :-)
73 Tom
___
Topband reflector - topband@contesting.com
-15 in the ground (and who knows if that also scales to 160), I'd use
the buried or laid on earth radials.
:-)
73 Tom
___
Topband reflector - topband@contesting.com
,
for example, one ground system provided 35-40 ohms of feed resistance and
another different system that provided almost 60 ohms of feedpoint
resistance had equal field strength.
I think N6RK and others have measured the same.
73 Tom
- Original Message -
From: DAVID CUTHBERT telegraph
That is quite an improvement. I had to have dropped the base impedance
from
400 ohms to 40 ohms for it to do that.
Things are often magic when we rely on feelings or emotions to measure
decibels.
___
Topband reflector - topband@contesting.com
will find around
here are gold connectors, unless they mate to another gold contact. I also
ALWAYS lube the connector with silicon dielectric compound.
73 Tom
___
Topband reflector - topband@contesting.com
, at least to me, appears to be based on anecdotal
unconfirmed opinions. Like deer whistles on cars.
73 Tom
___
Topband reflector - topband@contesting.com
a more serious issue.
73 Tom
___
Topband reflector - topband@contesting.com
and lines that significantly change
characteristics with weather conditions.
It is easier to make good transformers when impedance ratio of antenna mode
to transmission line mode is close to unity. That's why 400-600 ohm line
spacings are usually best.
73 Tom
tie it or beat it on 160, and why
it is reasonably on par with anything else on most bands above 80 meters.
73 Tom
___
Topband reflector - topband@contesting.com
wave vertical in black wet swamp soil. I wonder more
about how poor the one antenna was than how good the second one was.
73 Tom
___
Topband reflector - topband@contesting.com
.
The real problem is we have data based on assumptions or feelings without
verification.
73 Tom
___
Topband reflector - topband@contesting.com
.
73 Tom
___
Topband reflector - topband@contesting.com
on
160 SSB while driving down the highway. I can, at times, even beat others in
pileups from the mobile on 80 meters. Obviously if the Gap is as good as a
better mobile antenna, you can probably work a lot of DX with it.
73 Tom
___
Topband reflector
to over-the-air signals (pretty unlikely), it could be a problem.
It really depends more on the fence and local layout of things than anything
else, so the only way to really know is to just try it.
73 Tom
___
Topband reflector - topband
of the same size, the
resonant frequency and bandwidth does not shift. The only thing that
changes is the feed impedance, which goes up about four times.
73 Tom
___
Topband reflector - topband@contesting.com
Look on eBay, or Maxgain systems in Georgia owned by Alan Bond.
- Original Message -
From: Jerry Keller (K3BZ) k...@verizon.net
To: (REFLECTOR) Topband topband@contesting.com
Sent: Monday, December 10, 2012 9:29 AM
Subject: Topband: Vacuum Variable Source
I need 2 vacuum variable
messing the system up.
73 Tom
___
Topband reflector - topband@contesting.com
watts
Total load loss = 4.781 dB
Get ready for some serious core heating!
It isn't just this system either. Many systems will either fail to work
(from heat) or seriously waste materials if we simply decide 5000 ohms fixes
everything.
73 Tom
- Original Message -
From: Herb Schoenbohm he...@vitelcom.net
To: topband@contesting.com
Subject: Re: Topband: DX Window-Redux
On 12/6/2012 5:23 PM, Tom W8JI wrote:
There isn't any competition in any area can be all things to all people,
nor can it be completely fair to everyone
a tower mounted box could be used, the electrical design is
far more complex and more compromised.
73 Tom
___
Topband reflector - topband@contesting.com
I would hazard a guess that few of us enter it with an eye purely on
score. If
folks only entered contests they would win there would only ever be one
entrant
in each contest, a great loss for us all. I enjoy contest activity even
though
I've never won any :-)
Truer words were never spoken.
I stand by my suggestion and I don't see my suggestion as nonsense in
the least. Go here and read section 6.1
http://www.arrl.org/160-meter - The ARRL who host this contest state
plainly that this segment should be used for intercontinental QSOs
only, ergo: the DX window.
Since US VE are
. For example, I might CQ at 0500Z and
G3PU at 0505.
http://www.w8ji.com/160%20History/hist160dx.pdf
73 Tom
___
Topband reflector - topband@contesting.com
is not in an ARRL
section, it is DX.
Now Tom suggests that I should be sanctioned for calling CQ inside the
window...even though I am really looking for EU and Asia. I must not
answer NA stations calling because that is Intercontinental but a PJ of a
P4 a few hundred miles south of me can do so without
from the
tower.
The control and coax choke can be bifilar wound affair (if you can't run
control through the coax) and self resonant on 160.
73 Tom
___
Topband reflector - topband@contesting.com
...and that loss of the DX window is sadly, dear readers, why you will
seldom hear DX stations outside of Europe and North America CQing on 160m
in
the CQ contests.
Bit of a shame really, but that's (so-called) progress.
I never understood, and never agreed with the 160 committee abolishing
I had this happen many times as well but it is especially annoying near the
end of the contest when seeking to find those last few contacts that I heard
fellows calling CQ and only sending their call ONCE and then maybe waiting 2
sec. or less before sending CQ again.
160, with changing noise
So there is confused information about DX windows and digital windows
and callig windows and useless windows. Once upon a time there was
something called gentlemen's agreements and the DX window was part
of that. Most of us don't really let the ARRL dictate to us what we will
or won't do. So we
generally want to be bothered with facts or science. :-)
Unless we know what to measure and how to measure it, and actually measure
or compare something, we are just guessing.
73 Tom
___
Topband reflector - topband@contesting.com
think you are heading for long term problems with adaptors and a
transmitting switch.
73 Tom
___
Topband reflector - topband@contesting.com
of the conditions you mention, what specific
mechanism causes a path to be non-reciprocal at any instant of time?
I know why things like lossy networks can be non-reciprocal in impedance,
but what is the mechanism at work?
73 Tom
___
Topband reflector
, according to
relay suppliers, when lower current LED traffic lights replace old
incandescent lamps.
73 Tom
___
Topband reflector - topband@contesting.com
grade junk, it rusts.
Copperweld is (or was) used in long life outdoor support cables like for
bridges, so there may be local suppliers to you.
73 Tom
___
Topband reflector - topband@contesting.com
resistors. Id guesstimate the general F/B to be over 20dB on 160. My
feeling is that performance could not be duplicated by various other
loading methods. If somebody wants to make real world comparisons it might
be beneficial.
I looked at slinkys when I lived in Conyers. None of this is
If I wanted to measure the radial and feedline AC current, not having any
RF ammeters, I might just take a #47 lamp or other small pilot lamp and
stick it in series with the radial and transmit into it. 40 mA will make a
#47 lamp glow very dimly. Is this a good thing to check on?
Probably not
From the contest rules:
6.1. The segment 1.830 to 1.835 should be used for intercontinental QSOs only.
--
So, while the window might not officially exist, one is specifically
mentioned in the rules.
Tom - VE3CX
On Sat, Dec 1, 2012 at 12:54 AM, Carol Richards n
of space, or near a wavelength, we might as well use
two Beverages in stagger or echelon. It will have much higher F/B, much
more bandwidth, and be easier to build.
73 Tom
___
Topband reflector - topband@contesting.com
from three main
arrays, and either two or four directions from two smaller arrays.
73 Tom
___
Topband reflector - topband@contesting.com
any type of line can be made to work. It is all in the degree of
what we look for. I wouldn't be afraid to use twinlead lines, but I'd be
reluctant to use 50 year old audio paired cables or unshielded twisted pair.
I'm getting old and lazy but just not that cheap yet. :-)
73 Tom
With an Amphenol Type HN connector there is never any flashover.
SO-239's did not cut it. Type N is even worse.
A UHF connector won't flash over at 1500 watts if the VSWR is low.
Dave WX7G
HVN connectors will hold off about 5000-6000 volts peak. I used them a lot
in high power plasma
ON4UN states in his book that the wires for a 2 wire reversible beverage
must be installed side by side, but also may be placed one above the other
with satisfactory results.
Did someone try this? How satisfactory is satisfactory?
There is no difference at all.
If the feed system is right,
So, how to measure the bev? Is this procedure correct:
The bev is ~8 feet above ground. The far end is open, not grounded, no
resistor.
The analyzer connects directly to the bev and the ground rod at the rx end
through its bnc-to-banana plug adaptor . Measure and note the impedances
for 160,
suspect antenna coupling, a
defective component or connector, or a lightning protection device.
73 Tom
___
Topband reflector - topband@contesting.com
, and in nearly all
cases a few hundred ohms is enough. An exception might be if the ground
system common point has abnormally high voltages to earth (for example, a
single truncated radial) or if the coax is elevated and coupled to the
antenna.
73 Tom
** Ive noticed no difference in any weather using field phone wire which
happens to be in wide use by many very competitive contesters and lowband
DXers. With 5 2 wire reversibles here and 750' of 1/2 feedline there is
no need for a preamp.
I'm talking about:
1.) impedance change
2.)
Tom:
MOST antennas are in a neither world of being neither perfectly
balanced nor perfectly unbalanced.
How about an inverted L longer than 1/4 wave but optimized with series
capacitor? Any closer to perfect unbalanced?
Bob VE7BS
Hi Bob,
Take the case of a 1/4 wave groundplane with four
by anything from here).
73 Tom
___
Topband reflector - topband@contesting.com
frequency. Or are you switching in a long stub, to make
it an entirely different mode of operation?
73 Tom
___
Topband reflector - topband@contesting.com
antenna would
work. I suspect not nearly as well as an inverted L or T with modest ground
system.
73 Tom
___
Topband reflector - topband@contesting.com
told me stories about building massive bead
strings a few feet long on Yagi antennas!! Someone should stop the bead
madness enveloping us, and get us back to rational thought.
73 Tom
___
Topband reflector - topband@contesting.com
, including the CM injected and signal
level sensitivity of the antenna.
I make enough measurements of antennas here every year, some right in my
driveway near noise sources, to know when something is getting overblown.
73 Tom
___
Topband reflector
optimal compromises.
73 Tom
___
Topband reflector - topband@contesting.com
any info on this? Or can you refer me to a source?
Try this:
http://www.w8ji.com/g5rv_facts.htm
When I lived on a suburban lot, I phased my G5RV against a ~100-foot tall
insulated base tower. I had two unidirectional patterns and two
bi-directional patterns from that system.
73 Tom
there are many cases when needed outside the
ground panel.
73 Tom
___
Topband reflector - topband@contesting.com
Also the difference between Mix 31 and 43 is not great and was used for
decades successfully before 31 was introduced.
For a non-critical application like this almost anything would work with
enough core depth and/or turns, but they are not nearly the same. There is a
large difference
had DC grounded hi-Q cavities, and noise was exactly the same with
or without the cans. The same is true here at the house, where antenna with
or without element grounding are all basically the same, although I do
mitigate internal cable voltage buildup.
73 Tom
. A ground leak does not reduce the chance of a lightning strike,
either. Neither do those tower whiskers (NASA has extensively tested that).
73 Tom
___
Topband reflector - topband@contesting.com
I suspect most (or at least many) Americans are resistant to change and
unwilling to give anything different than what they are used to a fair try
before dismissing it.
When we were kids, we made fun of the occasional bitter old cranky Hams who
spent their lives being grouchy and cranky
away. I'm not sure that is a safe way to operate
though. :-)
73 Tom
___
Topband reflector - topband@contesting.com
in amplifiers. This is why storms charge insulated antennas almost as
easily as bare wire. Charge migrates right through the insulation.
73 Tom
___
Topband reflector - topband@contesting.com
. Most radios are good, but not all radios are
good at timing. Some hot switch on the leading edge, and some on the tailing
edge.
73 Tom
___
Topband reflector - topband@contesting.com
-static, the low antennas or antennas with blunt ends do not.
Grounding and static drains make no difference except for the popping when a
dielectric charges and arcs.
73 Tom
___
Topband reflector - topband@contesting.com
quieter for me for local storm static.
My bare wire Beverages here are dead quiet even while Yagi's are useless in
foul weather, unless the Beverage points at the towers or are near tall
trees.
73 Tom
___
Topband reflector - topband
minicircuits transformers on my Beverages here, because of
IMD.
A properly designed clamp would have no effect up to about 20-23 dBm, where
it would clamp hard, and would not include easily-saturated very small core
transformers.
Be careful with anything that uses back-to-back diodes.
73 Tom
even with close antennas.
73 Tom
___
Topband reflector - topband@contesting.com
a receiver limiter and do not want to hurt receiver dynamic
range on modern receivers, it takes far more circuitry than cheap
back-to-back diodes.
73 Tom
___
Topband reflector - topband@contesting.com
://www.w8ji.com/vacuum_tubes_and_vaccum_tube_failures.htm
73 Tom
___
Topband reflector - topband@contesting.com
, including small plastic fuel line hose,
insulating spaghetti, or even tape.
Myself, I'd stay with the largest possible system that would fit the area.
73 Tom
___
Topband reflector - topband@contesting.com
?
Lightning alone dictates bonding the cable to the tower, so any RF technical
issues are a moot point. (no, the tower will not shield the cable)
73 Tom
___
Topband reflector - topband@contesting.com
Thinking again about this, we have missed out a stage. After measuring the
tuner output impedance, we need to make a temporary L network which, when
terminated with 50 ohms, looks like the antenna. Now put the MFJ on this
terminated network and measure it's R +/- jX values which will
601 - 700 of 919 matches
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