My experience with two elevated resonant radials near (0.1 to 0.2
wavelengths) the tide line has been very positive during 4 DXpeditions.
The coverage is almost 180 degrees in the direction of the salt water
parallel to the tide line. The results are very good for verticals less
than 0.5
Sounds like a great project.
Isn't the reality that conductors (radials) in or near lossy mediums
(earth, even salt water) have loss? And that the near field extends
beyond the 1/4wl of the radials? The coupling among elements might be
the reason 4:1 matching was used.
So while more &
The 34 ohms is the sum of Rr (antenna radiation Z over perfect ground)
and Rg (ground R loss). Rr depends on the dimensions of the L plus a
bit of wire loss. My guess is Rr is about 10 ohms less than 34 ohms,
some easy modeling will determine it.
Then it is a question of what antenna
On 11/6/2022 09:02, Artek Manuals wrote:
In the end it is a signal to noise problem.
And there are more than two sides to that coin.
1. DXpedition site noise - a big risk factor with little that can be
known (except for desert islands) or solved in advance .
2. Differences in noise at
always confounded me when it comes to measuring ACTUAL
arrival angles
Dave
NR1DX
On 9/25/2022 10:25 AM, Grant Saviers wrote:
My perspective as originally a "1" in Boston and now residing near
Seattle, is the nickname "suffering sevens" is well applied to my
friends here in
My perspective as originally a "1" in Boston and now residing near
Seattle, is the nickname "suffering sevens" is well applied to my
friends here in the Pacific Northwest.
Simply, for the PNW, distance isn't that meaningful - it's path that
matters (and latitude). What was easy in Boston at
I think the disc-cone is a close relative. There is one of these on the
bow of the Iowa BB in Long Beach. During a tour by W6HB, I was told
they would have 25+ full duplex TTY circuits open at one time on this
and 4 whip antennas mounted on the superstructure.
Another piece of battleship
built.
I was impressed but did not fully appreciate its importance. I had
forgotten
about that visit till I read this message thread.
73 Pete - N8TR
At 01:25 PM 3/30/2022, Grant Saviers wrote:
The reference book of patterns for 2 and 3 element verticals is
Directional Antennas, by Carl E
Thanks for an interesting article.
I did a little reverse engineering from the KYW 1934 "4 square" picture
and commentary. A figure 8 pattern was the objective.
It seems to have used 8 radials elevated 10ft per tower. The text says
"55,000 feet of wire" in radial "cages". A little tough
Small signal, dry contact relays are made from different contact
materials than power relays made for higher voltages and currents. Any
fix that cleans them or removes the surface oxide that inhibits low
voltage signal transmission will likely be temporary. Plus the high
power relays are
Somewhat related was my effort to produce a pair of 80m notches so CW
and SSB could run 80m simultaneously on Field Day (separate antennas).
While the CW guys would be ok with 20KHz BW, not so for the SSB team.
Just below a Rx 40db notch was about the best I could do with a one db
loss Tx.
Having watched/been watched by the TARS aerostat radar off the coast of
FL, I would think that the "balloon" shape that generates lift with wind
would be the better choice for 160m verticals.
Helikite also balloon plus kite
https://en.wikipedia.org/wiki/Allsopp_Helikite
Never tried one, but
Another choice is to buy a cylinder, which is what most consumer/retail
users now do in the US. The 150 ft^3 cylinders were going for around
$180 empty pre covid. The specific cylinder can be refilled or
exchanged which has the advantage of free pressure recertification (at
least at my
Don't connect elevated radials to on/in ground radials.
There is a huge ground loss for 4ft high radials on 160m. 7ft is far
better and 10 ft is pretty good.
There are "W" shaped radial feeds with the base near to the ground but
IMO it is better to elevate the feedpoint to radial height and
1 5:21 PM, Grant Saviers wrote:
> I've not heard the term "accordian" applied, but the Tornado Tuner
> expands and compresses a coil inside some pvc pipe to change L
about
> 2:1. I have one (split) to tune the full 80m band at the center
of an
> 86ft
I've not heard the term "accordian" applied, but the Tornado Tuner
expands and compresses a coil inside some pvc pipe to change L about
2:1. I have one (split) to tune the full 80m band at the center of an
86ft rotatable dipole. Your choice of Al or Cu coil tubing with a small
Portescap
N7QT & I verified that black ring screw-in insulators are too conductive
for one or two transmit radials on 160m. Lot's of arcs and smoke. I
now use the yellow 4" long barb wire insulators screwed to trees to
support 160m elevated Tx radials.
Black may not be a problem with Beverage field
I've had 8x 125ft long 10ft elevated aluminum radials up for 7 years in
the forest of 100ft+ cedar, fir, and hemlock. Plenty of branch falls up
to 3". Maybe a few inches of sag and no breaks. Negligible stretch.
Using US brand real electric fence wire, 13 gauge. 9 ga is available.
Grant
Rick at al,
My comments in line
On 2/28/2021 12:31, Richard (Rick) Karlquist wrote:
On 2/28/2021 7:40 AM, Grant Saviers wrote:
The nice thing about switched serial caps (if same values) for tuning
upwards from a low resonance is the voltages are all the same. Plus
caps and appropriate
The nice thing about switched serial caps (if same values) for tuning
upwards from a low resonance is the voltages are all the same. Plus caps
and appropriate relays are cheap, easy, and small.
Rick, I think you might have suggested this to me, and my implementation
was published in QEX
Based on poor results (very low rdf) with no messanger RG6 over a barb
wire fence I built and subsequent modeling that showed this, I think
another parallel conductor near any Beverage is not a good idea. It was
easy to support the plain RG6 with PVC pipes tied to posts and I think
extending
Then with FT8, the "db" rating depends on S/N not signal power. I hear
well so my report is most frequently better than received. The big guns
are an exception with well engineered stations in good locations.
However, FT8 "db's" being S/N do wash out the gain loss when using Rx
antennas.
The advice we were given from Hi-Z for a new 4 square was not more
elevation difference between elements than ~4 feet. ~20% of element
length. The topography that happens between elements, eg spanning a
creek, might not matter much given the simple single ground rod ground
per element, but
For a portable helix loaded 160m vertical, I measured 1 and 2 127ft
radials at 3.5ft and 6.5ft above ground (average or worse) and found a
significant difference in the resonance R.
1 radial 3.5ft 50 ohms
1 radial @ 6.5ft 33 ohms
2 radials @ 6.5ft 28 ohms
Which quantified the change in ground
I question the wisdom of grounding the feedline shields at the antenna
for either open wire or coax designs. Was this a error in the schematic?
The bidirectional design using a coaxial cable shield for the antenna
does not need center tapped transformers. Good RG6 is ridiculously cheap
and
I've been using 8' 1.5" dia painted fiberglass top and bottom of my 85ft
T as standoffs from a fir tree. An 18" long bracket is lagged to the
tree both places to make it stable and lower the FG stress. OK after 6
years, occasional ice and snow.
PVC gets very flabby at 80F and higher and
Rudy Severns has many plots of elevated radial numbers, lengths, and
elevations on his web site antennasbyn6lf.com
My "T" showed the expected change in feedpoint Z as I added 125ft long
10ft elevated radials from 2 to the current 8. The last two made no
measurable difference. From Rudy's
For a literal "pair of radio wave glasses":
Given the vertical gain of a practical 160 dipole is pretty much cloud
burner and a decent 160 vertical is pretty much low angle, IF you know
the actual real gain patterns, then it is possible to compare signal
amplitudes (probably real time
I agree with Dave's comments based on measurements and modeling of two
different similarly sized top loaded verticals.
Grant KZ1W
On 11/7/2020 07:49, Dave Cuthbert wrote:
Steve,
*I believe there is a measurement error. *
1. The reactive part of the input impedance should not become more
Rick,
Did you CM choke the power and signal leads? or the whole cable?
Grant KZ1W
On 10/7/2020 07:22, Mark - N5OT wrote:
In my head this is becoming "101 uses for old network cable" which is
great because I've got a ton of it coiled up neatly and set aside but
not thrown away :-) Thanks
My DX Eng 4 sq (12v over RG6 to preamps) has had infuriating random arc
noise for years and the W3LPL explanation makes great sense to me as the
reason. I did silicone grease the F threads but followed the "CW
advice" to not flood the connector so I have a project to do that.
Hi-Z had a
Worse than "not the best" or "not a good idea" from prior
experimentation. My two Beverages 6 feet up (10' total Z) over a 4
strand barb wire fence did not work - very poor directivity. One N-S
and one E-W. Then some NEC2 modeling showed 6db directivity over 3
strands of barb wire. However,
There have been a few comments about Rx antenna chokes. What I built
may be of interest.
10 turns of RG179 micro TFE 75 ohm coax thru a Fair-Rite 2631101902 #31
core (1.12od x 1.125L x .54id). Wound thru a 3d printed form with 10
slots that keeps the turns disciplined in order.
Measured R
I fried the reed switch turns counter in my variable L tuned 80m dipole.
A bozo moment at QRO way off tune. So, I think all sensors need
protection from high RF fields.
Grant KZ1W
On 8/24/2020 09:25, Phil Duff wrote:
At least 2 rotor manufacturers (Orion, Spid) have used a simple pulse
Given the thickness of the foil and the likely surface treatment, I
think soldering is going to be difficult.
I've watched a TIG welding genius butt weld Coors aluminum cans (<0.004"
thick) together. That might work. Maybe a spot weld ala a Si chip wire
bonder.
Grant KZ1W
On 6/1/2020
"If NEC2 is wrong, so is NEC4." - I don't think so since a different
ground modeling approach is available in NEC4.2. Running EZNEC Pro4
antennas both in 2 and 4.2 sometimes shows significant differences.
My .02. Exactly where is ground? It sure isn't the flat smooth plane
in NEC. And
FYI some data which I found interesting
My dry earth at end of summer to very wet winter (WWA) causes my
lightning ground system DC (actually about 300Hz AC) resistance to vary
about 40% lower, ie 7+ ohms to 5 ohms. There was also significant
differences from rod to rod re resistance
More power to make up for my 10db excess noise = xxx Kw - whoopee! Need
to get some 3 phase.
Remote Rx, eg 100km makes a lot more sense. Clubs could put up shared
facilities.
With direct sampling synchronous receivers and down sampling of say the
bottom 50Khz of 160, every user could
comments in line
On 3/5/2020 10:02, Gabriel - EA6VQ via Topband wrote:
I have some doubts about installing and inverted L with elevated radials for
160m. I have been searching in Google and find some contradictory
information, so I would appreciate very much if you can help me with your
own
I agree there is much F connector junk out there. However Amphenol does
make a "4 hole" female F chassis jack, an excellent product. digikey
usually has stock
https://www.digikey.com/product-detail/en/amphenol-rf/222146/ACX1545-ND/1989993
Unless one has the $250 D chassis punch for D
aircraftspruce.com (but airplane stuff is $)
If it is really dacron then http://synthetictextilesinc.com/supportham.html
And available at several ham radio suppliers.
Maybe you want nylon based, this ebay seller has high quality
"para-cord" also called "550 line" I suspect originally
Charge it to 5Kv and apply to appropriate body part.
Grant KZ1W
On 2/7/2020 19:34, Roy Morgan wrote:
I looked at the picture and description. Can anyone guess how that thing "could
cause cancer or reproductive harm" ??
Roy Morgan
K1LKY Western Mass
On Feb 7, 2020, at 9:16 PM, HP wrote:
Rob,
I considered this for my MM SSB. It doesn't work. Several published
tests prove that. Ok as an AC/DC ground.
Grant
On 1/9/2020 01:18, Herbert Schoenbohm wrote:
A very effective device called *Dynaplate* works very well as a saltwater
grounding system for boats or limited areas to
Important facts about salt water are the attenuation of a wire submerged
10" at 1MHz is -87db and at 4S/m the conductivity is 10,000,000 times
less than copper wire.
Putting a single radial in a lossy medium doesn't work very well,
whether it is dirt or saltwater. Radials elevated in low
Likely >$3000 for a real "enclosure" that size, probably custom, painted
and 2x for stainless. Plus how to move and ship about >700#. Grainger
has big enclosures, but nothing your size. You might find a switchgear
enclosure at a electrical recycler. I had a old CNC controls cabinet 4w
x 5h
Mike,
I think the problem with elevated radials in 4 squares is the mutual
coupling and the necessity that the radial current and impedance be
equal. Otherwise the pattern is distorted.
Having measured my 8 125' elevated radials there is a significant (>2:1)
current imbalance in them due
For my relay reversible DHDL's used on 160 & 80m, I'm using 0.1uf 500v
DC blocking capacitors, particularly the Kemet X7R MLCC SMD ones.
digikey 399-6747-1-nd There are enough parts for reversibility that I
designed a small PCB with ExpressPCB so SMD parts made sense.
The RFC inductor choice
Check antennasbyn6lf.com. Rudy did a number of measurements of ground
properties.
Grant KZ1W
On 12/7/2019 17:13, Mikek wrote:
I once saw a print up of laying out a Dipole on Ground and doing
measurements
and adjusting length and then using that to figure out a proper length
for a BOG.
Does
The goal is admirable. I did some modeling of inductor shortened BOGS
with EZNEC Pro4 and found it is extremely sensitive to height above
ground. A half an inch change in height can reverse the pattern. Thus,
I consider it an impractical antenna given the nature of most real
ground surfaces,
A DHDL is somewhat ground independent so might be a choice. Raising the
base of one end with 66' separation isn't too tough on the slope. It is
possible to phase a couple of them. Then add some relays to make it
reversible from the shack.
Curious as why non resistor spark plugs aren't on the list of choices.
Easy to gap. Pt-Pt electrodes last forever (100k miles). There was a
ham mounting two on a Cu plate for ladder line, but that was many years ago.
Grant KZ1W
On 10/7/2019 2:21 PM, Jim Thomson wrote:
Date: Sun, 6 Oct 2019
ared me
David G4FTC
From: Topband on behalf of Grant Saviers
Sent: 01 September 2019 00:13
To: Topband@contesting.com
Subject: Re: Topband: Drones for antenna installation?
I stick to max 80psi which has a good safety factor vs the pipe rating
(4" @220psi in my launcher). Very cold weath
I stick to max 80psi which has a good safety factor vs the pipe rating
(4" @220psi in my launcher). Very cold weather and knocking it around
when brittle or anytime is certainly to be avoided. An alternative is
to buy schedule 80, McMaster sells sch 80 PVC in 5 foot lengths. The
pressure
ZL3IX I think by accident had a fence with a break in it. My not
working Beverage was 4'up over a continuous welded wire fence. Then
some NEC2 modeling of a 600' Beverage 6' above a continuous 3 wire
(wires at 2,3, & 4') barb wire fence, showed poor F/B. Mine was worse
over the welded 6"x 6"
Lots of questions, maybe a little bit of useful answers from me.
First, I doubt there is any BOG that will cover 8 octaves with a useful
pattern. Unobtanium, IMO.
Second, your question did cause me to investigate improving the RDF of a
240' BOG which is on my to try list. So using
As a minority report by one, IMO the simplest, smallest, cheapest, good
RDF receive antenna is the DHDL. RDF around 9, pretty good for $20 of
wire, one BN-73-202, one resistor, some string and two trees (free here)
or supports 65' apart. Ground rods for a 200' BOG will cost more, take
more
Here is what I used when I had the same problem 50kw line of sight 4
miles 1MHz. Expensive, but worked very well.
http://herostechnology.co.uk/pages/RF_Filters.html
Having the filter between rig and amp worked fine for me. 200w rating
for the Heros.
My power line had ~1v of RF, so ebay
That statement doesn't agree with my quick modeling (I also wondered why
my 40' base had some observed benefit on high bands now and then). Both
a 60' for 160 and 40' for 80/40 worked fine.
for a 60' baseline, 6' Z bottom wire, 30' Z to top or about 190' of wire:
Freq Gain dbi F/B db peak
You don't mention how high you will be above sea level. Too high and
the "L" gain & angle won't improve as much as within 1/2 WL and a few
meters above sea level. So the 160L is ok at 80m from the tide line but
the 80m ought to be closer if you can manage that. More than a
wavelength from
I recently found Rudy N6LF article from ARRL Antenna Compendium Vol 6 re
short 10' elevated top band radials. Resonated with a single loading
coil, as short as 50' worked well, only down 0.5db from full size.
Grant KZ1W
On 5/4/2019 9:14 AM, N4ZR wrote:
At the risk of setting off a
I lived on Mt Hamilton Road for 20 years, but that ended 8 years ago.
I'm not aware of any hams further up Mt Hamilton than the Grandview
restaurant and Three Springs Ranch development. There are two FM or UHF
TV towers on the hill SSW of there. They are in the FCC database. My
ranch/QTH
36 N-miles in 5.5 hrs = 6.5 kts pretty good to hold it that low if as
reported 51 mph wind to 100 gusts. Enough speed to preserve steerage
but as little as possible to minimize distance lost.
Seems that the Captain knows what he is doing.
Grant KZ1W
On 3/26/2019 16:42 PM,
I got as close as the Falklands on a small cruise ship and operated
C6A/KZ1W/MM aboard ship. Here is a South pole view of where the rare dx
are located around Antarctica.
Inside the convergence zone (solid line around the continent) is where
the WX is awful 365 x 24. The dashed line is
Here is a app that gives distances and initial bearing for the great
circle track from lat-lons. Of course that may be meaningless given prop.
http://www.gpsvisualizer.com/calculators
Grant KZ1W
On 3/23/2019 11:07 AM, Ralph Parker wrote:
Try "DX Atlas" from Alex, VE3NEA .
My experience with 142 wound on 240-31 cores would agree with Jim's
experiment. NO problems after years in service. It is well known that
TFE insulation is subject to creep - I've proved that in wire wrap
service with cut thru shorts. However, that is with the wire tight
against as sharp an
Likewise worked a bunch of JA's this am from Seattle, most were strong
-5 to +3 on my Rx 4sq listening NW. Will try other directions. No Tx
directivity here. No JA's on 1908 to start, but after a few 1840 CQ JA
the rate was good.
Grant KZ1W
On 1/30/2019 11:56 AM, daraym...@iowatelecom.net
Al Christman K3LC thoroughly sliced and diced the tradeoffs of number vs
length for given total wire investment is his Mar/Apr 2004 NCJ paper.
N6LF also has a lot to say.
Grant KZ1W
On 1/22/2019 16:11 PM, Chortek, Robert L. wrote:
“Wes cut his radial length to match the vertical L section
Guy,
I need some more db's on Tx. For Rx I hear much better than heard into
EU from Seattle area. It's a hard path and easy to believe EU QRN/QRM is
the main culprit. Your "loss list" is a great list, but I am thinking
about a different potential problem with my T with eight 125' long
Problem #1. The swr indicates about a 140Khz plus < 2:1 bandwidth (2 *
1880-1810) which implies a high radial resistance. Are the elevated
radials fully insulated from trees, not contacting foliage, etc? Add
three more.
Problem #2. Your coiled coax choke may be making things worse. Check
Modeling I've done shows it a bad idea to have in ground and elevated
radials connected together, but that is not clear from what you
described. Then with the elevated separate, moving the feedpoint up at
least 8', to 12' is better and elevated radials run out at that height.
I think it is a
I saw 8+ stations all calling VP8EME MANY times. So he was widely heard
and here (Seattle) about -13. I only saw a couple of Q's completed, so
you were not alone. I had worked him before and remember it wasn't that
difficult, but obviously he was having hearing problems tonight. It is
I have tried most means for "line over branch" - slingshots with
spinning reels, bow and arrow, arborist swing toss weights (that is a
skill I don't have), fishing pole with sinker, tree climber, boom lifts,
and finally the CSV19. Easily launches to 135'. The last is by far the
winner. After
My 160m T tuner uses 3x Schrack PCB SPST relays. 900w FT8 and full QRO
SSB. No problems in 4 years. 12vdc PCB relay by Schrack (RZ01-1A4-D012)
with a plastic arm from the coil armature to the contacts that is rated
5000v coil to contact isolation, 12a at 250vac switching, and has
redundant
I'll second the success with the CSV19 tennis ball launcher. You won't
need the top model for 60' trees but I do recommend the fishing archery
spool option for paying out the line - very smooth and snag free. The
PE braid is so light that one problem is how far the wind drift will
take it.
The are a number of drone remote releases available. Given the small
payload capacity of cheap drones the weight is critical for everything -
line + release + sinker. The polyethylene woven fishing line has
amazing strength and low weight. I use it for my tennis ball launcher
to top 120'
A DHDL will fit in a lot less length and work better IMO than either
Beverage choice. You can put relays in small boxes at the feed
transformer and termination to flip the directivity with two feedlines.
If you have the width then a 4sq receive will beat any other choice in
215 ft. But, any
the individual verticals degrades the directive pattern
that we are trying to achieve.
73, John W1FV
-Original Message-
From: Grant Saviers [mailto:gran...@pacbell.net]
Sent: Monday, October 22, 2018 11:38 AM
To: jkaufm...@alum.mit.edu; Topband@contesting.com
Subject: Re: Topband: elevated
I know at least CW operator N7QT will operate diversity reception, not
sure it was yet in operation.
Grant KZ1W
On 10/22/2018 10:57 AM, Tree wrote:
Sometimes - near your sunrise - angles go high and that diminishes
directivity quickly.
Congrats on the QSO!!
Tree N6TR
On Mon, Oct 22, 2018
I have a 160m T with 8 elevated 125' radials and the currents are worst
case 3:1 unequal for various reasons (nearby steel building & towers).
I've modeled this with EZNEC Pro4 by placing the actual radial currents
as sources in each radial. Obviously the sum of those currents must
equal the
Several suggestions, some already mentioned -
Although your swr plot shows you are in the ballpark for resonance, the
feedpoint resistance is very low, as mentioned likely 12 to 20 ohms. A
transmission line transformer stepdown will help a lot. 4:1 likely the
best choice. If parts are hard
Interesting source. The 5356 alloy would be the best choice for radial
wires since the 5xxx series are of a corrosion resistant aluminum
alloy. 5052 is the usual alloy for boat hulls in salt water.
OTOH, it seems the cost of 14ga THHN, the fact that it will last
forever, and that it is
Me too.
Or the inverse as I did, cut my T for the low end of the band. Then
three series capacitors with PCB relays to short each individually
(none, 1, 2, or 3) yielded nearly full band coverage <1.5:1 swr. My T
is 85' to top and a 50:25 ohm TLT is a close match, then the capacitor
stack
Agree, my DX Eng 4 sq vertical array (high impedance) is almost always
the winner on 160 vs an 85' T, a toss up with a 2L beam @157' on 80m,
and rarely better than the 3L 40m @ 140'. So I believe the 4sq RDF
numbers are valid. Another plus: when p-static kills the 80m beam the
4sq is the go
Interesting. Must be a fun place in the middle of Antarctic winter and
keeping a 160m antenna up. OTOH, they can lay wire on the ice for a 660
ft elevated dipole.
I had 3 SSB QSO's with them on 20m when I was MM in the Southern Ocean
Jan 2017. From the newbies on the radio I think getting
Agree. At my QTH 47.6 N (Seattle) the oval is almost always in the way
to EU so long path on 80 is more reliable winter months if the EU's hang
around for the west coast sunrise. So far EU on 160 has been very
difficult. Not complaining since I was one of the lucky 120 that worked
KH1 on
I agree that resonating 8 elevated radials would be a aggravating task.
I have 8 10' elevated 125' +/- radials for my T loaded vertical. I
made no effort to resonate them. OTOH, for one or two radials,
resonating them is important. N6LF covered this in his papers on
elevated radials.
Have you tried an SFX-500 connector? These are made for 1/2" bare Al
hardline, 50 ohm but the 75 ohm center conductor should be smaller
diameter.
With a steppIR beam a broadband match is needed which rules out the
common coax matching section. Sevick has designs of transmission line
Small ditch diggers are usually available at Home Depot here and
certainly at rental yards. For aggregated materials try and find one
with carbide teeth, which last 10x longer than hardened steel.
Also, cable companies use what is essentially a carbide toothed circular
saw blade trencher,
On a couple of DXpeditions we damaged the front end of a couple of
analyzers by transmitting on a nearby antenna on a different band so
this is another hazard to be aware of.
Grant KZ1W
On 6/11/2018 10:14 AM, terry burge wrote:
Jim,
There is room that the 0.01-0.02uF cap could go in. Due to
I pulled >1500' of 1" pvc water line in glued together 200' lengths 8"
beneath an adobe cattle pasture using a Kellems swivel grip attached to
a single point ripper on a 70hp tractor.My ripper was 1" plate on a
3 point hitch so start and stop was easy. A hole was dug at each 200'
joint to
JC,
Have you read the papers I cited? Looked at numerous reports from
DXpeditions and several antenna experts re the performance of verticals
NEAR salt water?
google "vertical antenna near salt water" for a longer list of
references re a well proven fact.
Grant KZ1W
On 6/5/2018 4:34
It is well known by DXpeditioners and an EZNEC analysis demonstrates
that verticals within 1 wavelength of the sea have greatly enhanced gain
at low elevation angles in the seaward direction. There is no need for
the antenna to be over water for that benefit. In the opposite
direction the
For simulating a solid conducting plate in NEC with wires, Roy Lewallen
(EZNEC author) advises 0.1 wavelength on a side squares of wires. That
would be 16m for topband. Since adding the mesh is a search for tenths
more db's, be conservative and use half his recommendation, 8m or 25'.
If a
Dave,
Remember that the reported S/N is relative to the receive station noise
+ QRM level. Since many TB stations don't have your antennas and have
high noise, they can't decode you or report a poor S/N. I get +9 and
-18 reports from YB stations a hundred KM apart. It's not spotlight
Yep, automatic TTY networks go back a lot more than 50 years. Certainly
with the Model 19 in the 1940s and probably before that.
The ASR-33 and its "stunt box" are a true marvel of low cost mechanical
engineering. Send WRU, asking "who are you?" And the automatic answer
back - "HERE IS" a
I measured the Comtek bead balun on 160m and found there is low choking
resistance.
I use the K9YC design with good results, whether it will make any
difference in your antenna system is something you will need to try.
With more than 5x the choking resistance with the K9YC 7T on 5 #31core
One issue is probably the orientation of the Belize beach vs path to
VK/ZL. A vertical on the beach within .7 wavelengths of the tide line
has pronounced gain seaward. That gain is at the expense of the land
side pattern. For an antenna on a pier the pattern doesn't get
symmetrical until a
I also use wire wrap wire. The Kynar insulation is designed to not cut
thru against a sharp corner wire wrap post, no need to insulate
ferrite. I use 26 or 30 gauge. Multi colors are fun and available in
small spools on ebay in both gauges. No messing with Xacto scraping off
the polyimide
What I used for data transmission line Z finding was a pulse gen, scope
and variable resistor (non inductive). A fast risetime pulse reflects
very clearly on the scope at the source. When the terminating resistor
equals line Z the reflection disappears, usually a shelf up or down on
the
Radials need to be elevated and insulated from ground/earth or on the
ground and grounded. I tried a modeling exercise to see if a ground
screen under elevated radials would improve efficiency but it wasn't
very helpful. Even over salt water, it is better to insulate elevated
radials or
1 - 100 of 201 matches
Mail list logo
