TobBanders,
I will be on 1827.5 every evening at my SS from 0400 to 0430 (mainly for EU)
and then from 1000 to 1200 and again from 1545 to 1615 (my SR), until Apr 8.
(Times are +- depending on conditions.)
I normally QSY to 80 at 0430 just after EU SR. Yesterday at my SS conditions
on 160 were terrible, but 80 was doing great. Then later, starting around
1000 Z signals on 160 were amazingly strong, both from NA and JA (and Korea)
but the lightning crashes were even stronger!
I have a lot of t-storm noise here (and no RX ANT). My noise level goes from
-125 dB to -80 dB during the crashes that come every two to three seconds!
Please send your call three times to give me chance to "assemble" it. (-80
dB is about equivalent to S9 +5 dB!)
GL and 73,
George,
FO/AA7JV
On Tue, 4 Apr 2023 12:32:20 -0500 David Raymond wrote:
George has been QRV 160 cw most mornings NA time, sometimes earlier rather than
later. He's typically Q5 for the most part but not strong here. . .usually S3
or S4 peak with QSB to virtually nil.
73. . . Dave, W0FLS
On 4/4/2023 12:09 PM, W3HKK@roadrunner.com wrote:
I looked for George for the 3rd straight day on 160, but no copy.However there
he was on 3527.5 at 1107z, with a very nice 579 sig andI quickly put him in the
log. Well after my sunrise hr in Ohio I sawspots for him on 160 cw from several
West Coast US stations.
Havent heard a dx station on 160 at my SR for at least three days now,but had
some nice short contacts with assorted VK's on 40 and 20 ssbaround 1130z.
Pulled 9U5RU out of the noise on 10m ssb shortlythereafter, so some sigs have
been there for the taking.
The VKs on 20 ssb were 5 S units stronger on the LP when I firstcontacted them,
but at the end of the qso they were just 2 S unitsstronger LP. Wonder what else
was coming through that I may havemissed?
-----------------------------------------From:topband-request@contesting.comTo:
topband@contesting.comCc:Sent: Tuesday April 4 2023 12:00:44PMSubject: Topband
Digest, Vol 244, Issue 4
Send Topband mailing list submissions to topband@contesting.com
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Contents of Topband digest..."
Today's Topics:
1. Re: High Impedance RX Antennas (Dennis W0JX) 2. Re: High Impedance RX Antennas (Frank W3LPL) 3. Re: High
Impedance RX Antennas (Tree) 4. Re: High Impedance RX Antennas (Don Moman VE6JY) 5. Re: High Impedance RX Antennas (John
Kaufmann) 6. Re: [PVRC] 2-element receiving arrays (Dave Cuthbert) 7. Re: High Impedance RX Antennas (Jim Brown)
----------------------------------------------------------------------
Message: 1 Date: Mon, 3 Apr 2023 16:42:37 +0000 (UTC) From: Dennis W0JX To:
"topband@contesting.com" Subject: Re: Topband: High Impedance RX Antennas Message-ID: Content-Type: text/plain;
charset=UTF-8
There is an old saying "The enemy of good is perfect."? You will bedriven crazy by chasing down
every slight variance from the ideal.That being said, it is important to check out the obvious areas whereflaws
can create big problems. Indeed, the feedline coax, typicallyRG6 CATV line, is a major contributor to array
performance problems.?The cheap, big box cable is covered with PVC and that stuff hardensand tightens up over the
years. This allows water to enter the shieldand the water easily migrates for long distances, creating a
highresistance. Spend the money upfront and buy quality cable that isflooded. The idea of using cable
that has a solid copper conductor has merit.But even with that, a bare copper conductor will oxidize over time.
Ifind myself cleaning these conductors on an annual basis with theeraser end of a pencil (recommended by Lee
K7TJR). I have also had F connector
failures on my combiner box and on acommon mode choke. Sometimes the
imported female connector centercontact just fails for no reason. The
alternative Amphenol connectorsare very expensive at about $8+ each but I am
considering replacingthe connectors with these higher grade parts. Also,
the so-called "water-proof" compression connectors are oftennot. The
connection must be waterproofed effectively.? Also,condensation from
humidity can be a big problem. Here is northeastOhio, the environment is
humid for the majority of the year. I havepoured water out of a 75 ohm
preamp that was sheltered in a goodenclosure! These complex phasing arrays
are by no means plug and play. Eachinstallation will be unique depending on
layout and surroundingobjects. There are three tools necessary to get them
and keep themworking:? 1.) a good portable signal source to feed the
antennapreamps (I use an
Elecraft XG-3 with a home brew impedance transformerat the input);? 2.) a
portable transceiver to measure signal out ofthe system at various points
(My KX3 does a great job); and anaccurate antenna analyzer to measure
impedances and to measurefeedlines and phasing lines for the proper
electrical lengths. N6RK isright. There can be considerable difference in
RG6 impedance so youneed to check it out.?
73 Dennis W0JXMilan, OH
------------------------------
Message: 2 Date: Mon, 3 Apr 2023 13:11:27 -0400 (EDT) From: Frank W3LPL To:
topband Subject: Re: Topband: High Impedance RX Antennas Message-ID:
Content-Type: text/plain; charset=utf-8
Another highly recommended tool is a Time Domain Reflectometer. Tt easily detects any
abnormalities in my 8-circle and 4-square arrays and stacked HF Yagi arrays and switches.
Other than my hand held antenna analyzer, my hand held TDR is my most often used and most valuable tool for proving
that theperformance of my antennas and feedlines has not changed from prior measurements and identifying and
isolating faults before they cause partial or total failure. A TDR can detect, diagnose and locate feedline
and antenna faults from the comfort of your ham shack.
Affordable TDRs are often available on eBay. Some antenna analyzers have rudimentary TDR
capabilities but I've never used an antenna analyzer with TDR capabilities comparable
in performance to a TDR.
Long before moisture causes coax failure, it causes the impedance of the coax to change, a
potentially big problem in a phased array or stacked Yagis. A TDR easily detects and locates the
problem before it causes a failure.
An antenna analyzer can also detect that moisture has caused an impedance shift in coax cable. Place a dummy load
(with the same impedance as the coax) at one end of the coax cable. Sweep the antenna analyzer frequency. As you
do a frequency sweep the VSWR and impedance should not change. If it does, moisture is probably eating away
inside your coax.
73 Frank W3LPL
----- Original Message ----- From: "Dennis W0JX via Topband" To: "topband" Sent:
Monday, April 3, 2023 4:42:37 PM Subject: Re: Topband: High Impedance RX Antennas
There is an old saying "The enemy of good is perfect."? You will bedriven crazy by chasing down
every slight variance from the ideal.That being said, it is important to check out the obvious areas whereflaws
can create big problems. Indeed, the feedline coax, typicallyRG6 CATV line, is a major contributor to array
performance problems.?The cheap, big box cable is covered with PVC and that stuff hardensand tightens up over the
years. This allows water to enter the shieldand the water easily migrates for long distances, creating a
highresistance. Spend the money upfront and buy quality cable that isflooded. The idea of using cable
that has a solid copper conductor has merit.But even with that, a bare copper conductor will oxidize over time.
Ifind myself cleaning these conductors on an annual basis with theeraser end of a pencil (recommended by Lee
K7TJR). I have also had F connector
failures on my combiner box and on acommon mode choke. Sometimes the
imported female connector centercontact just fails for no reason. The
alternative Amphenol connectorsare very expensive at about $8+ each but I am
considering replacingthe connectors with these higher grade parts. Also,
the so-called "water-proof" compression connectors are oftennot. The
connection must be waterproofed effectively.? Also,condensation from
humidity can be a big problem. Here is northeastOhio, the environment is
humid for the majority of the year. I havepoured water out of a 75 ohm
preamp that was sheltered in a goodenclosure! These complex phasing arrays
are by no means plug and play. Eachinstallation will be unique depending on
layout and surroundingobjects. There are three tools necessary to get them
and keep themworking:? 1.) a good portable signal source to feed the
antennapreamps (I use an
Elecraft XG-3 with a home brew impedance transformerat the input);? 2.) a
portable transceiver to measure signal out ofthe system at various points
(My KX3 does a great job); and anaccurate antenna analyzer to measure
impedances and to measurefeedlines and phasing lines for the proper
electrical lengths. N6RK isright. There can be considerable difference in
RG6 impedance so youneed to check it out.?
73 Dennis W0JXMilan, OH _________________ Searchable Archives:
http://www.contesting.com/_topband [1] - TopbandReflector
------------------------------
Message: 3 Date: Mon, 3 Apr 2023 10:20:26 -0700 From: Tree To: Frank W3LPL Cc:
topband Subject: Re: Topband: High Impedance RX Antennas Message-ID:
Content-Type: text/plain; charset="UTF-8"
I guess most people have some kind of small antenna analyzer that hasa
TDR kind of function.
I have not warmed up to them yet as the results I see seem to be "allover the
place". Maybe I just don't know how to use them yet.
My goto TDR is homebrew - using an analog scope.
Here is one design pretty similar to what I am using:
A very simple TDR from W2AEW ? PierpaLab.com [2] I put a switch on it to slow down the rep rate
as an option since some of my "stuff" is pretty long.
It works wonderfully to check feedlines and beverages. I have onebeverage that has transformers and
feedlines on both ends and I can see the difference between open/short/terminate on the "far end"
(which is physically in the shack).
73 Tree N6TR
On Mon, Apr 3, 2023 at 10:11?AM Frank W3LPL wrote:
> Another highly recommended tool is a Time Domain Reflectometer. > Tt easily detects any abnormalities in my 8-circle and 4-square > arrays and stacked HF Yagi arrays and switches. > > Other than my hand held antenna analyzer, my hand held
TDR is my > most often used and most valuable tool for proving that theperformance > of my antennas and feedlines has not changed from priormeasurements > and identifying and isolating faults before they cause partial or > total failure. A TDR can
detect, diagnose and locate feedline and > antenna faults from the comfort of your ham shack. > > Affordable TDRs are often available on eBay. Some antenna > analyzers have rudimentary TDR capabilities but I've never used > an antenna
analyzer with TDR capabilities comparable in > performance to a TDR. > > Long before moisture causes coax failure, it causes the impedance > of the coax
to change, a potentially big problem in a phased array > or stacked Yagis.
A TDR easily detects and locates the problem > before it causes a
failure. > > An antenna analyzer can also detect that moisture has
caused > an impedance shift in coax cable. Place a dummy load (with the >
same impedance as the coax) at one end of the coax cable. Sweep > the
antenna analyzer frequency. As you do a frequency sweep the > VSWR and
impedance should not change. If it does, moisture is > probably eating away
inside your coax. > > 73 > Frank > W3LPL > > > > > > -----
Original Message ----- > From: "Dennis W0JX via Topband" > To:
"topband" > Sent: Monday, April 3, 2023 4:42:37 PM > Subject: Re: Topband:
High Impedance RX Antennas > > There is an old saying "The enemy of good
is perfect." You will bedriven > crazy by chasing down every slight
variance from the ideal.
Thatbeing > said, it is important to check out the obvious areas where
flawscan create > big problems. Indeed, the feedline coax, typically RG6
CATV line,is a > major contributor to array performance problems. The
cheap, big boxcable > is covered with PVC and that stuff hardens and
tightens up over theyears. > This allows water to enter the shield and the
water easily migratesfor > long distances, creating a high resistance.
Spend the money upfrontand buy > quality cable that is flooded. > The idea
of using cable that has a solid copper conductor hasmerit. But > even with
that, a bare copper conductor will oxidize over time. Ifind > myself
cleaning these conductors on an annual basis with the eraserend of > a
pencil (recommended by Lee K7TJR). > I have also had F connector failures
on my combiner box and on acommon > mode choke. Sometimes the imported
female connector
center contactjust > fails for no reason. The alternative Amphenol
connectors are veryexpensive > at about $8+ each but I am considering
replacing the connectorswith these > higher grade parts. > Also, the
so-called "water-proof" compression connectors are oftennot. > The
connection must be waterproofed effectively. Also, condensationfrom >
humidity can be a big problem. Here is northeast Ohio, theenvironment is >
humid for the majority of the year. I have poured water out of a 75ohm >
preamp that was sheltered in a good enclosure! > These complex phasing
arrays are by no means plug and play. Each > installation will be unique
depending on layout and surroundingobjects. > There are three tools
necessary to get them and keep them working:1.) a > good portable signal
source to feed the antenna preamps (I use anElecraft > XG-3 with a home
brew impedance transformer at the
input); 2.) aportable > transceiver to measure signal out of the system at
various points(My KX3 > does a great job); and an accurate antenna analyzer
to measureimpedances > and to measure feedlines and phasing lines for the
properelectrical > lengths. N6RK is right. There can be considerable
difference in RG6 > impedance so you need to check it out. > > 73 Dennis
W0JXMilan, OH > _________________ > Searchable Archives:
http://www.contesting.com/_topband [3] -Topband > Reflector >
_________________ > Searchable Archives: http://www.contesting.com/_topband
[4] -Topband > Reflector >
------------------------------
Message: 4 Date: Mon, 3 Apr 2023 11:33:10 -0600 From: Don Moman VE6JY To: "Topband@Contesting.
Com" Subject: Re: Topband: High Impedance RX Antennas Message-ID:
Content-Type: text/plain; charset="UTF-8"
A used Tek 1502 TDR is the "gold standard" to me anyway and they canbe quite cheap at flea markets etc. They are "arm held" and
selfcontained portable so ideal for up to 1000' runs and have enough resolutionthat you can "see" defects that you don't really need to worry about.
Theadvantage over some of the VNWA's that have a TDR function, is that the 1502 isreal time so intermittents can easily be spotted. And it measuresimpedance
so you can easily see how long and what Z that unknown roll of fleamarket coax is!
I built the scope based TDR from the QST articles years ago, but that version isn't
even close to the 1502. I also have a Tek 1503 forchecking longer runs of control cable etc.
73 Don VE6JY
On Mon, Apr 3, 2023 at 11:21?AM Tree wrote:
> I guess most people have some kind of small antenna analyzer thathas a TDR > kind of function. > > I have not warmed up to them yet as the results I see seem to be"all over > the place". Maybe I just don't know how to use them yet. > > My goto TDR is homebrew - using an analog scope. > > Here is one design pretty
similar to what I am using: > > A very simple TDR from W2AEW ? PierpaLab.com > [5] I put a > switch on it to slow down the rep rate as an option since some ofmy > "stuff" is pretty long. > > It works wonderfully to check feedlines and beverages. I have onebeverage > that has transformers and feedlines on both ends and I
can see the > difference between open/short/terminate on the "far end" (which is > physically in the shack). > > 73 Tree N6TR > > On Mon, Apr 3, 2023 at 10:11?AM Frank W3LPL > wrote: > > > Another highly recommended tool is a Time
Domain Reflectometer. > > Tt easily detects any abnormalities in my
8-circle and 4-square > > arrays and stacked HF Yagi arrays and
switches. > > > > Other than my hand held antenna analyzer, my hand held
TDR is my > > most often used and most valuable tool for proving that
theperformance > > of my antennas and feedlines has not changed from
priormeasurements > > and identifying and isolating faults before they
cause partial or > > total failure. A TDR can detect, diagnose and locate
feedline and > > antenna faults from the comfort of your ham shack. > > >
Affordable TDRs are often available on eBay. Some antenna > > analyzers
have rudimentary TDR capabilities but I've never used > > an antenna
analyzer with TDR capabilities comparable in > > performance to a TDR. >
> > Long before moisture causes coax failure, it causes the impedance >
of the coax to change, a
potentially big problem in a phasedarray > > or stacked Yagis. A TDR easily
detects and locates the problem > > before it causes a failure. > > > >
An antenna analyzer can also detect that moisture has caused > > an
impedance shift in coax cable. Place a dummy load (with the > > same
impedance as the coax) at one end of the coax cable. Sweep > > the antenna
analyzer frequency. As you do a frequency sweep the > > VSWR and impedance
should not change. If it does, moisture is > > probably eating away inside
your coax. > > > > 73 > > Frank > > W3LPL > > > > > > > > > > > >
----- Original Message ----- > > From: "Dennis W0JX via Topband" > > To:
"topband" > > Sent: Monday, April 3, 2023 4:42:37 PM > > Subject: Re:
Topband: High Impedance RX Antennas > > > > There is an old saying "The
enemy of good is perfect." You willbe > driven > > crazy by chasing down
every
slight variance from the ideal. Thatbeing > > said, it is important to
check out the obvious areas where flawscan > create > > big problems.
Indeed, the feedline coax, typically RG6 CATV line,is a > > major
contributor to array performance problems. The cheap, bigbox > cable > >
is covered with PVC and that stuff hardens and tightens up overthe >
years. > > This allows water to enter the shield and the water
easilymigrates for > > long distances, creating a high resistance. Spend
the moneyupfront and > buy > > quality cable that is flooded. > > The
idea of using cable that has a solid copper conductor hasmerit. But > >
even with that, a bare copper conductor will oxidize over time. Ifind > >
myself cleaning these conductors on an annual basis with theeraser end >
of > > a pencil (recommended by Lee K7TJR). > > I have also had F
connector failures on my combiner box and
on acommon > > mode choke. Sometimes the imported female connector
centercontact just > > fails for no reason. The alternative Amphenol
connectors are very > expensive > > at about $8+ each but I am considering
replacing the connectorswith > these > > higher grade parts. > > Also,
the so-called "water-proof" compression connectors areoften not. > > The
connection must be waterproofed effectively. Also,condensation from > >
humidity can be a big problem. Here is northeast Ohio, theenvironment is >
humid for the majority of the year. I have poured water out of a75 ohm >
preamp that was sheltered in a good enclosure! > > These complex phasing
arrays are by no means plug and play. Each > > installation will be unique
depending on layout and surroundingobjects. > > There are three tools
necessary to get them and keep themworking: 1.) a > > good portable signal
source to
feed the antenna preamps (I use an > Elecraft > > XG-3 with a home brew
impedance transformer at the input); 2.) a > portable > > transceiver to
measure signal out of the system at various points(My KX3 > > does a great
job); and an accurate antenna analyzer to measureimpedances > > and to
measure feedlines and phasing lines for the properelectrical > > lengths.
N6RK is right. There can be considerable difference inRG6 > > impedance so
you need to check it out. > > > > 73 Dennis W0JXMilan, OH > >
_________________ > > Searchable Archives:
http://www.contesting.com/_topband [6] -Topband > > Reflector > >
_________________ > > Searchable Archives:
http://www.contesting.com/_topband [7] -Topband > > Reflector > > >
_________________ > Searchable Archives: http://www.contesting.com/_topband
[8] -Topband > Reflector >
------------------------------
Message: 5 Date: Mon, 3 Apr 2023 14:09:32 -0400 From: "John Kaufmann" To: "'Topband@Contesting.
Com'" Subject: Re: Topband: High Impedance RX Antennas Message-ID: Content-Type: text/plain; charset="utf-8"
Another tool I've found indispensable for setting up andtroubleshooting phased vertical
RX arrays is a two-port VNA. I use anArray Solutions VNA-2180 (now discontinued) for critical
measurements.I also have a NanoVNA H4 (https://nanovna.com/) [9] which is a
very"affordable" VNA that can be used as a portable, handheld, standaloneinstrument
and that you can take out in the field. In most cases, theNanoVNA H4 is more than good enough.
There is a learning curve to using a VNA. However, once you learn it,you'll be
able to make very accurate measurements of delay linelengths, preamplifier gain and
phase, phase combiner gain and phase.Most VNA's also have a TDR function, although
it is usually based onfrequency domain measurements that are transformed to the time
domain.
I'm running a homebrew RX array and it would have been almostimpossible to get
it running as well as it is now without a VNA.
73, John W1FV
------------------------------
Message: 6 Date: Mon, 3 Apr 2023 09:04:26 -1000 From: Dave Cuthbert To: Frank W3LPL Cc:
topband , PVRC Subject: Re: Topband: [PVRC] 2-element receiving arrays Message-ID:
Content-Type: text/plain; charset="UTF-8"
It seems that padding the element capacitance as needed for equal capacitance
would help.
Dave KH6AQ
On Thu, Mar 30, 2023 at 4:48?PM Frank W3LPL wrote:
> Hi Dave, > > Anyone who has experimented with a high impedance antenna such > as an end fed half wave has experienced the extreme environmental > influence on the feedpoint impedance of a high impedance feed. > > The required spacing to trees and buildings is very difficult topredict > with any confidence. The impedance of a high impedance element > -- and hence the amount of voltag if feeds into the
preamp -- > is heavily influenced by its immediate environment. > > If all of the high impedance verticals in an array do not producethe > same voltages from the signals received by the array, the pattern > of the array and especially its nulls are significantly degraded. > > 73 > Frank >
W3LPL > > > > > > > > From: "K3ZJ David Siddall" > To: "Frank W3LPL" > Cc: "topband" , "PVRC" , > "Pete N4ZR N4ZR" > Sent: Friday, March 31, 2023 12:34:28 AM > Subject:
Re: [PVRC] Topband: 2-element receiving arrays > > Frank, > " wrt
to-negative effects of nearby trees and buildings." for high > impedance
verticals: > > Is there any data measuring how much loss if placed in the
woods?Minimum > distance from a tree to minimize the loss? Are their other
effectstoo, > such as less directionality? > > 73, Dave K3ZJ > > > >
On Thu, Mar 30, 2023 at 1:38 PM Frank W3LPL < [ mailto: >
donovanf@starpower.net | donovanf@starpower.net ] > wrote: > > > Hi
Pete, > > For a monoband receiving array, you might consider using
lowimpedance > resonant verticals rather than high impedance
verticals. > > The primary advantages of high impedance verticals are > -
very short verticals (but taller verticals produce strongersignals) > -
multi-band operation > - no radials > > The primary disadvantages are >
- reliability issues with outdoor
electronics > - lightning susceptibility of outdoor electronics > - higher
cost > - much lower signal levels > - extreme care required to suppress
common mode signals (buriedfeedlines > are highly recommended) > -
negative effects of nearby trees and buildings. > > The primary advantages
of low impedance verticals are > - much stronger signal levels > - much
less criticality of common mode signal suppression, > - much lower cost >
- much higher reliability > - immunity to lightning damage > - much less
affected by nearby trees and buildings > > The primary disadvantages
are > - taller verticals (typically about 24 feet) > - radials (they can
be very short if many radials are used) > - mono band operation (switchable
matching networks can be used for > multi-band operation). > > I highly
recommend the DX Engineering Receiving Antenna PhasingSystem. > Its
expensive
but well worth the investment especially for a smallarray. > > [
https://www.dxengineering.com/parts/dxe-ncc-2 [10] | >
https://www.dxengineering.com/parts/dxe-ncc-2 [11] ] > > If you have 120
feet for a three element array, the YCCC array is agreat > choice > It can
use high impedance or low impedance verticals > Unfortunately its no longer
available from DX Engineering > The nine element YCCC array uses only three
active elements at anytime, > so its really a three element array
switchable in many directions. > >
[ >https://static.dxengineering.com/global/images/instructions/dxe-yccc-switch.pdf?_gl=1*1cv0fc9*_ga*MjEyMDA1Nzc3MS4xNjUyMzAyMjc0*_ga_NZB590FMHY*MTY4MDE5NTk1OC40My4xLjE2ODAxOTYwNTYuNTAuMC4w
/> >
| >https://static.dxengineering.com/global/images/instructions/dxe-yccc-switch.pdf?_gl=1*1cv0fc9*_ga*MjEyMDA1Nzc3MS4xNjUyMzAyMjc0*_ga_NZB590FMHY*MTY4MDE5NTk1OC40My4xLjE2ODAxOTYwNTYuNTAuMC4w
/> > ] > > [ https://www.youtube.com/watch?v=dl-crM5Kb6A [12] | >
https://www.youtube.com/watch?v=dl-crM5Kb6A [13] ] > > [
https://www.youtube.com/watch?v=lVW1CmrzP7c [14] | >
https://www.youtube.com/watch?v=lVW1CmrzP7c [15] ] > > A two element array
occupies only 60 feet or even a little less. > > 73 > Frank >
W3LPL > > > ----- Original Message ----- > From: "Pete N4ZR N4ZR" < [
mailto:pete.n4zr@gmail.com | > pete.n4zr@gmail.com ] > > To: "topband" < [
mailto:Topband@contesting.com |Topband@contesting.com > ] > > Sent:
Thursday, March 30, 2023 12:54:30 PM > Subject: Topband: 2-element
receiving arrays > > Thinking ahead to next winter on 160, I'm interested
in replacingmy >
K9AY Loop with a 2-vertical phased array. I'd like to homebrew the >
antennas and just buy or build the remote control unit for theshack. > I'm
looking for sources of components (antenna-located preamps andan > in-shack
controller), and would prefer not to completely homebrewthem, > but the
prices at the usual suspects are awfully high. Any ideas? > > I have
pretty reasonably-priced access to 25 and 31-foot fiberglass > poles (used
for wind-socks by model airplane enthusiasts). I'mthinking > that one
relatively low-cost approach might be to attach, say, #14wire > to the
poles, with preamps at the base, but wonder if there is a > downside to
using such small-diameter antenna elements rather than1 or > 1.5 inch
tubing? Alternatively, are clones of the DX Engineering 8' > short
verticals with preamps a good alternative? > > -- > 73, Pete N4ZR >
_________________ >
Searchable Archives: [ http://www.contesting.com/_topband [16] | >
http://www.contesting.com/_topband [17] ] - Topband Reflector >
______________________________________________________________ > PVRC
mailing list > Home: [ http://mailman.qth.net/mailman/listinfo/pvrc [18] |
> http://mailman.qth.net/mailman/listinfo/pvrc [19] ] > Help: [
http://mailman.qth.net/mmfaq.htm [20] | > http://mailman.qth.net/mmfaq.htm
[21] ] > Post: mailto: [ mailto:PVRC@mailman.qth.net |
PVRC@mailman.qth.net] > Message delivered to [ mailto:davek3zj@gmail.com
|davek3zj@gmail.com ] > > This list hosted by: [ http://www.qsl.net/ [22]
|http://www.qsl.net [23] ] > Please help support this email list:
[http://www.qsl.net/donate.html [24] | > http://www.qsl.net/donate.html
[25] ] > > > > _________________ > Searchable Archives:
http://www.contesting.com/_topband [26] -Topband > Reflector >
------------------------------
Message: 7 Date: Mon, 3 Apr 2023 12:18:02 -0700 From: Jim Brown To:
topband@contesting.com Subject: Re: Topband: High Impedance RX Antennas Message-ID:
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On 4/3/2023 10:20 AM, Tree wrote: > I guess most people have some kind of small antenna
analyzer thathas a TDR > kind of function.
In my professional life in pro audio, I started doing Time Domain Spectrometry in 1982, so I have a pretty good handle on how it
works. There is a mathematical relationship between the frequency responseof a system and its time response -- one is the inverse of the
other. The Fourier Transform of the time response yields the frequency response, and the Inverse Fourier of the frequency response yields the
time response. Modern antenna analyzers produce a swept frequencyresponse, and associated software running on the computer does the
InverseFourier Transform of a sweep to produce the TDR.
For more than 10 years, the best of the low cost Vector Network Analyzers has been the VNWA3SE, built and sold as a finished
andtested unit, by SDR Kits, run by hams in UK. The unit, its firmware, and associated software, was designed by DG8SAQ,
an EE prof. Support from both DG8SAQ and SDR Kits is excellent -- both read and respond totheir support email reflector.
Current cost with shipping is about $560 (depending on currency).
https://www.sdr-kits.net/introducing-DG8SAQ-VNWA3 /> Greatest precision (ability to see small things) is
provided by asweep over a very wide frequency range. I usually sweep from 50-500 MHz.Once the sweep is
done, the TDR is simply a few more button pushes in the menu system.
73, Jim K9YC
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