Re: Topband: Inverted-L question

[Guy Olinger K2AV]

Hi Steve,

5300 pF is way large. It indicates *something *else is going on.
"Something" needs to be determined.

One thing for sure, after nearly a decade of correspondence with this as a
frequent subject, there is no one single "silver bullet" to fix this in all
cases. It is complicated and with several distinctly different causes, each
one by itself capable of causing the symptoms you report. Only *one *of the
several causes is* not* also causing significant RF loss that minimizes
your radiated TX power.

Worse, quite often two or three of them are in effect at the same time. And
excellent reports and suggestions by those trying to help out seem like an
argument about which solution is "the one". In fact, all of the respondents
may be making an excellent suggestion about *one *of the* several ways* the
problem reported above can be caused.

Very unfortunately, one may have to fix all two or three or four to get the
antenna acting with an ideal modeled result.

*So, apologies for the length*, but this one possibly takes a silver
bullet, plus a gold bullet, plus a platinum bullet, plus a depleted uranium
bullet to solve all the possibles responsible for this report. So on to the
stuff

The *large* capacitor needed means that the amount of inductive X being
tuned out *is getting small.* If what you did was lengthen the Inv L
horizontal to get 50Ω R and then use a series capacitor to tune out the
inductive X, the method has a blind spot where the* inductive reactance at
R=50Ω is so low that the cap has to be huge. *

This is usually caused with an Inv L because there is* a lot of **fixed RF
loss R somewhere* added to the L's natural 20-35Ω radiation R at X=0Ω. The
Inv L is decidedly not a natural 50Ω antenna. X=0Ω should not be close to
R=50Ω

If you take away the added loss, the now needed extra length to get R=50Ω
all from radiation resistance (lengthening the horizontal) is substantial.
The longer length has a lot larger inductive X to tune out. This *reduces *the
size of the cap needed. *Smaller *pF value caps produce the *larger
*capacitive reactance
to cancel out that larger inductive X.

And of course it could be that something in the environment is giving you
an "X push" one way or the other.

So exactly *what *is the added RF loss, or X push, and *what *is causing
it?

To start, you have an *undefined* tower involvement which is capable of
producing a very large RF loss addition to that tower-supported 1/4
wave-ish L, *and at the same time *also capable of producing a very large X
push in a capacitive *or *inductive direction.

Anything in the k2av.com "Loss List"
 could
be adding ohms to the feedpoint R.

One of the splendidly frustrating things about 160 meter antennas is,
unless we can put up a 160 dipole at 250', we probably need to go vertical
oriented.

We can't do problem-solving on vertical-antennas-for-160 accurately or
effectively without considering several overwhelming factors on 160: Loss,
ground effects, and a monstrous wavelength which multiplies miscellaneous
conductor involvement.

These can't be reliably determined or solved by tuning for SWR. You're only
trying to match* (antenna + problems)* to 50Ω.

The inverted L with the bend supported by the tower, and fed at the
radials, is really a transformer in disguise. *The L is one winding of the
"transformer". The tower and each coax shield and control conductor on the
tower are separate windings in this multi-winding ad-hoc "transformer".*

Somewhere in my stuff I have a NEC 4 model of an L supported at the bend by
a tower that has more induced current in the tower than there is in the L.
This transformer situation has an *effective *turns ratio that keeps the
tower with lower voltage and higher current. This higher current is then
driven into and dissipated in the ground.

If your tower cabling has:

All its shields and unused conductors in the cable grounded to the tower at
the base...

And all active control conductors bypassed to the tower at the base…

Then Tree's suggestion to detune the tower works to its maximum
effectiveness.

But tower detuning has to be done well. Otherwise the induction to the
tower will still drive a lot of current into the ground. The induced RF
current in ungrounded or unbypassed coax shields and control conductors
will be driven into ground via capacity effect all along their lengths
laying on or buried in the ground between the tower and the shack This loss
adds to the R of the L feed through the above transformer effect.

A second issue is whether the radial's center is solidly connected to the
tower's cable grounding point. That will substantially reduce the dirt's R
that the induction is forcing RF into.

One case I was involved in violently changed the feed Z when the tower base
was bonded to the radial feed. The performance picked up substantially and
he only needed a 5:4 turns ratio transformer to get close to 50 ohms after
pruning the L for X=0. Until 

Re: Topband: Inverted-L question

[Michael Tope]

Remember, Steve, for a given frequency more capacitance equals less 
capacitive reactance [Xc = 1/(2*pi*f*c)]. At 1825 KHz, 5300 pf is only 
16.5 ohms reactance. That means you are only offsetting a small amount 
of inductive reactance. Where you should be more concerned is when the 
series capacitance is very small. That is when capacitive reactance (Xc) 
gets large and the RF voltage across the series capacitor can get very 
high.


73, Mike W4EF..

On 12/20/2023 5:43 PM, Steve Muenich wrote:

I have an Inverted-L question that hopefully someone can answer for me.

I  installed the 160m  wire to the 80 ft level on a 100 ft Rohn 45 tower
with top mounted yagis.
The horizontal (sort of) portion is approx 45ft long.
The wire starts at 80 ft down approx 5 ft from tower and when it gets to
the match box the bottom of the wire is about 10ft away from tower.

I have about 50 or so 120 ft long radials.

I am able to get a X=0, R=52. SWR 1.19:1 tune according to my RE Zoom using
load shunt match at base of tower.

My question is why do I need so much series capacitance (5300pf) with
parallel inductance approx 8uh?

Everything is working fine, but I am wanting to understand why I am needing
so much series capacitance? Does this indicate an issue I need to resolve?

TIA,

Steve, NA5C
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Re: Topband: Inverted L Question

[Pete Smith N4ZR]

FWIW, for 160 I used my old 97-foot Rohn 25 tower, with 2 tribanders and 
a 40M 2-el on it, shunt fed at about 50 feet.  I had a pair of 300 uf 
variable caps at the bottom, one in series with the feed and the other 
in parallel.  It proved to be easy to tune to low SWR once I discovered 
that the local 500-watt radio station on 1500+ KHz went to low power at 
6 pm, so my MFJ analyzer didn't freak out from the received signal.


73, Pete N4ZR

On 12/21/2023 4:55 PM, Jim Brown wrote:

On 12/21/2023 12:54 PM, Paul Dulaff via Topband wrote:
Ran a basic EZNEC model with no tower present for your 80 ft X 45 ft 
inverted L at 1.825 Mhz. The base impedance for this is 28.5 - j 130 
ohms.  The get rid of the reactance I extended the top wire an 
additional 20 ft so 80 X 65 ft and base impedance is 37.2 + j0. The 
tower is definitely influencing the inverted L.


Neighbor K6RB described a 160 vertical running next to his tower, and 
I don't remember him do anything to detune the tower. Yes, the tower 
becomes part of the antenna, but that isn't a bad thing as long as we 
take it into account to match it to the line. AND -- unless the line 
is quite long or uses lossy coax (like RG58), excess loss on 160M is 
quite low.


I've seen (and used) a simple equation for determining the effective 
diameter of a triangular tower. An NEC model should include that, as 
well as aluminum at the top.


For my Tee, I adopted the ancient and accepted practice of making the 
horizontal element long enough that the feedpoint Z became 50 +jX at 
the desired center of operation, and added series C at the feedpoint 
to equal -jX. I can do this because my Tee is strung between tall 
redwoods.


I ended up with C in the range of 800-900 pF. What's required here is 
capacitors with very low loss, but not particularly high voltage, 
because they're at a high current point, not a high voltage point. So 
their voltage rating is tied to peak value of TX power. I had a stash 
of low loss caps in the 2-3kV range, and used those in parallel, in a 
weatherproof box.


73, Jim K9YC

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Re: Topband: Inverted L Question

[Jim Brown]

On 12/21/2023 12:54 PM, Paul Dulaff via Topband wrote:
Ran a basic EZNEC model with no tower present for your 80 ft X 45 ft 
inverted L at 1.825 Mhz. The base impedance for this is 28.5 - j 130 
ohms.  The get rid of the reactance I extended the top wire an 
additional 20 ft so 80 X 65 ft and base impedance is 37.2 + j0. The 
tower is definitely influencing the inverted L.


Neighbor K6RB described a 160 vertical running next to his tower, and I 
don't remember him do anything to detune the tower. Yes, the tower 
becomes part of the antenna, but that isn't a bad thing as long as we 
take it into account to match it to the line. AND -- unless the line is 
quite long or uses lossy coax (like RG58), excess loss on 160M is quite 
low.


I've seen (and used) a simple equation for determining the effective 
diameter of a triangular tower. An NEC model should include that, as 
well as aluminum at the top.


For my Tee, I adopted the ancient and accepted practice of making the 
horizontal element long enough that the feedpoint Z became 50 +jX at the 
desired center of operation, and added series C at the feedpoint to 
equal -jX. I can do this because my Tee is strung between tall redwoods.


I ended up with C in the range of 800-900 pF. What's required here is 
capacitors with very low loss, but not particularly high voltage, 
because they're at a high current point, not a high voltage point. So 
their voltage rating is tied to peak value of TX power. I had a stash of 
low loss caps in the 2-3kV range, and used those in parallel, in a 
weatherproof box.


73, Jim K9YC

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Topband: Inverted L Question

[Paul Dulaff via Topband]

Steve

Ran a basic EZNEC model with no tower present for your 80 ft X 45 ft 
inverted L at 1.825 Mhz. The base impedance for this is 28.5 - j 130 
ohms.  The get rid of the reactance I extended the top wire an 
additional 20 ft so 80 X 65 ft and base impedance is 37.2 + j0. The 
tower is definitely influencing the inverted L.


Best 73's

Paul - W2NMI



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Topband: Inverted-L Question

[Tom Boucher]

Steve,
For comparison my inverted-L is similar to yours with a 94 ft vertical
section and 43 ft horizontal (ish). It is on a tall tree, not a tower.

Like you, I use an L-network to match it and get a feed impedance on 1826.5
KHz of 50+j0. I have a 1600pF capacitor in parallel but no inductor as I
simply extended the antenna length to make it slightly inductive.

73,
Tom G3OLB
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Re: Topband: Inverted-L question

[Tree]

Without getting into the measurements - I think you need to detune the
tower if that is going to work at all.  Probably put a trap in the bottom
20 feet.

Tree N6TR

On Thu, Dec 21, 2023 at 6:27 AM Noel Lopez via Topband <
topband@contesting.com> wrote:

> Here is my 2 cents worth.  First of all, I am not an antenna expert nor do
> I know how to use antenna modeling software.These are my thoughts based on
> my experience and what I remember reading.  My low band system is an
> inverted L under a SteppIr yagi that can be retracted.  This avoids the
> capacitance hat effect on the inverted L.
> The capacitative top hats you have on your tower make the inverted L
> "appear" longer thus requiring morecapacitance to match the inverted L.
> If there were no yagis to create capacitance over the inverted L,
> the antenna would appear shorter and require less capacitance to match.
> Capacitative matching is less lossy and more efficient than inductive
> matching from what I remember.
> I am posting this to see if anyone can add-to or correct my comments.
> Noel Lopez NR5R
> On Wednesday, December 20, 2023 at 07:52:00 PM CST, Steve Muenich <
> srmuen...@gmail.com> wrote:
>
>  I have an Inverted-L question that hopefully someone can answer for me.
>
> I  installed the 160m  wire to the 80 ft level on a 100 ft Rohn 45 tower
> with top mounted yagis.
> The horizontal (sort of) portion is approx 45ft long.
> The wire starts at 80 ft down approx 5 ft from tower and when it gets to
> the match box the bottom of the wire is about 10ft away from tower.
>
> I have about 50 or so 120 ft long radials.
>
> I am able to get a X=0, R=52. SWR 1.19:1 tune according to my RE Zoom using
> load shunt match at base of tower.
>
> My question is why do I need so much series capacitance (5300pf) with
> parallel inductance approx 8uh?
>
> Everything is working fine, but I am wanting to understand why I am needing
> so much series capacitance? Does this indicate an issue I need to resolve?
>
> TIA,
>
> Steve, NA5C
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> Reflector
>
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>
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Re: Topband: Inverted-L question

[Noel Lopez via Topband]

Here is my 2 cents worth.  First of all, I am not an antenna expert nor do I 
know how to use antenna modeling software.These are my thoughts based on my 
experience and what I remember reading.  My low band system is an inverted L 
under a SteppIr yagi that can be retracted.  This avoids the capacitance hat 
effect on the inverted L. 
The capacitative top hats you have on your tower make the inverted L "appear" 
longer thus requiring morecapacitance to match the inverted L.    If there were 
no yagis to create capacitance over the inverted L, the antenna would appear 
shorter and require less capacitance to match.  Capacitative matching is less 
lossy and more efficient than inductive matching from what I remember.
I am posting this to see if anyone can add-to or correct my comments.
Noel Lopez NR5R
On Wednesday, December 20, 2023 at 07:52:00 PM CST, Steve Muenich 
 wrote:  
 
 I have an Inverted-L question that hopefully someone can answer for me.

I  installed the 160m  wire to the 80 ft level on a 100 ft Rohn 45 tower
with top mounted yagis.
The horizontal (sort of) portion is approx 45ft long.
The wire starts at 80 ft down approx 5 ft from tower and when it gets to
the match box the bottom of the wire is about 10ft away from tower.

I have about 50 or so 120 ft long radials.

I am able to get a X=0, R=52. SWR 1.19:1 tune according to my RE Zoom using
load shunt match at base of tower.

My question is why do I need so much series capacitance (5300pf) with
parallel inductance approx 8uh?

Everything is working fine, but I am wanting to understand why I am needing
so much series capacitance? Does this indicate an issue I need to resolve?

TIA,

Steve, NA5C
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Topband: Inverted-L question

[Steve Muenich]

I have an Inverted-L question that hopefully someone can answer for me.

I  installed the 160m  wire to the 80 ft level on a 100 ft Rohn 45 tower
with top mounted yagis.
The horizontal (sort of) portion is approx 45ft long.
The wire starts at 80 ft down approx 5 ft from tower and when it gets to
the match box the bottom of the wire is about 10ft away from tower.

I have about 50 or so 120 ft long radials.

I am able to get a X=0, R=52. SWR 1.19:1 tune according to my RE Zoom using
load shunt match at base of tower.

My question is why do I need so much series capacitance (5300pf) with
parallel inductance approx 8uh?

Everything is working fine, but I am wanting to understand why I am needing
so much series capacitance? Does this indicate an issue I need to resolve?

TIA,

Steve, NA5C
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Topband: Inverted L - I surrender

[N4ZR]

I'm going to take the antenna back down tomorrow, test to be sure that 
there's nothing freaky like a break in the wire, and then take it and my 
K9AY loop in for the season.  Mowing starts in another few weeks and I'd 
just as soon roll up my radials for another day.  In the meantime I'll 
rewind the choke on a #31 core and try again next fall.


Thanks everyone for trying - I learned some things I didn't know before, 
anyway.


--
73, Pete N4ZR
Check out the new Reverse Beacon Network
web server at .
For spots, please use your favorite
"retail" DX cluster.

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Re: Topband: Inverted L with elevated radials for topband

[Jeff Blaine]

When it comes to elevated radials, the amount of guys who have strong 
opinions on the subject are many - and unfortunately the amount of 
objective data behind those strong opinions is generally not existent.  
On the other hand, the N6LF work is one of the few well documented 
objective works available.


You won't go wrong drawing your radial design based on the N6LF graphs.  
As far as the performance and feedpoint question goes, build the best 
ground you can and then cook up the match network based on the measured 
values.


73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com


On 3/5/20 5:43 PM, Grant Saviers wrote:

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 experience.

As noted by others, N6LF has a wealth of modeled and measured data on 
elevated radials.    antennasbyn6lf.com




The antenna would be supported by a 16 m (52.5 ft) high fiberglass pole
placed on top of a 3m (10 ft) high small tower with the horizontal 
part of
the L slopping down to a 5 m (16 ft) high mast about 23 m (75 ft) 
away.  Two
to four tuned elevated radials can be placed, although they will have 
to be

bent due to space restrictions.


By "tuned" do you mean resonant 130ft +/-?  Again N6LF has data for 2 
to 16 elevated radials, and with more they can be shorter.
Also see his paper in Antenna Compendium 8 re inductively loading for 
shorter radials.  I had only 2 75ft radials on a 52' mast.


Now the doubts:


What impedance can I expect at the feed point with this configuration?

Having the radials as high as possible will minimize ground losses and 
decease Z.  With 2x at 10ft plan on 25 to 30 ohms.


How to match it in order to feed it with a 50 ohm cable?  Some pages say
that no match is required, only a choke. Other pages say a hairpin is
necessary as the impedance can be too low. So other say that a tuner 
at the

base is required?    I am confused L


SWR losses on 160 are so low that a 2:1 doesn't cost many db's. Too 
keep your amplifier happier I use a 50::25 ohm transmission line 
transformer.  make it or buy it.


A good choke is a must.  Make the K9YC 4" #31 choke.



What performance for DX can be achieved by this antenna?  Is it 
really good
or do you have some better suggestion for a really small lot where no 
ground

radials are possible?

You won't do better with anything else.  More radials will improve it 
slightly.


Would it be worth to use a higher fiberglass pole, let's say 4 m (13 ft)
higher, in order to lengthen the vertical section of the L? Would the
difference be noticeable?



The taller the better but probably less than 1 db gain.



Anyone has real experience setting up this antenna with elevated 
radials?

Most information I can find on Internet is related to ground mounted
antennas.


Read all of what Rudy N6LF says, and you will be an expert.

Grant KZ1W





Thanks in advance!


73. Gabriel - EA6VQ


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Re: Topband: Inverted L with elevated radials for topband

[sawyered]

I haven’t experimented on top band but I have tried elevated radials on 80M
¼ verticals.  I had one in Houston Texas that worked wonderfully – elevated
8 radials at about 10 ft.  Ground conductivity in Houston was about as good
as anywhere in the US.  I tried doing the same thing at 2 different QTHs in
Vermont and both were very disappointing.  I gave up on elevated radials for
80 and 160M.

 

My experience has been that ground conductivity matters for a small number
of elevated radials.

 

I have been much happier with 48 – ¼ wave ground radials.

 

Ed N1UR

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Re: Topband: Inverted L with elevated radials for topband

[Wes]

I second this.

Wes  N7WS


On 3/5/2020 4:43 PM, Grant Saviers wrote:


Read all of what Rudy N6LF says, and you will be an expert.

Grant KZ1W


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Re: Topband: Inverted L with elevated radials for topband

[donovanf]

"Sooner or later everything old is new again" (Stephen King) 


February 1922 QST page 30 



The 1BCG antenna used for the transatlantic tests was a T cage 
over a radial counterpoise. The antenna is hung between two pipe 
masts 230 feet apart, and 108 and 75 feet high, respectively. 
The two horizontal sections of the T-vertical are each 50 feet long. 
The vertical section is 70 feet over the top of the counterpoise. 
The elevated counterpoise consisted of thirty 60 foot wires 
The operating frequency was 1500 kilocycles 


http://p1k.arrl.org/pubs_archive/4361 


73 
Frank 
W3LPL 

- Original Message -

From: "Bill Stewart"  
To: "Gabriel - EA6VQ"  
Cc: "topband"  
Sent: Thursday, March 5, 2020 8:13:08 PM 
Subject: Re: Topband: Inverted L with elevated radials for topband 

Hi Gabriel, 
These comments will be of little help as far as the technical info on the 
subject antenna 
and is a far cry from an excellently constructed antenna but it is very 
practicalin my 
opinion of course. 

However, I do use an Inv. L with a four wire counterpoise...or elevated radials 
if you 
prefer. Mine is approximately 50ft vertical and rest horiztotal, a quarter 
wave. The 
horizontal part is about 50 feet high and fairly flat. The antenna is 
completely covered 
over with tall pine trees. The CP wires go off from the base/feed point 10ft 
off the ground 
and at approximately 90 degrees apart. Each CP wire is about ten feet high and 
some are 
supported on tree trunks, others have some PVC posts for support and seems the 
CP wire 
lengths are a bit shorter than a 1/4 wave lgth, but my memory may not be too 
good on this 
part. I feed it with RG8X...I only run 100 watts(CW) on 160no need for big 
coax in my 
case. I just used a door-knob cap between the vert and CP at the basecan't 
remember the 
value but think I just experimented until I got the SWR goodalso think I 
did some trimming 
on the CP wires. I have had very good success with this antenna. With 100 watts 
I have been able 
to work several DXped. stns in the Pacific, JA. This season I have worked 
nearly 80 EU, Carib 
and Pac. stations. I had a lot of fun in the recent ARRL CW test. No, I don't 
get every station 
I call, but enough to keep me happy. The purist, with all their instruments and 
computer 
programs would laugh at my version, but it seems to be an easy antenna to get 
working and, 
at least in my case, a decent antenna. (I also use it for receiving...works 
well there too). 
Try iteasy to put up and if it don't work, go on to something elsehi. 
GL & 73 de Bill K4JYS/NC 

- Original Message - 
From: "topband"  
To: "topband"  
Sent: Thursday, March 5, 2020 1:02:07 PM 
Subject: Topband: Inverted L with elevated radials for topband 

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 experience. 



The antenna would be supported by a 16 m (52.5 ft) high fiberglass pole 
placed on top of a 3m (10 ft) high small tower with the horizontal part of 
the L slopping down to a 5 m (16 ft) high mast about 23 m (75 ft) away. Two 
to four tuned elevated radials can be placed, although they will have to be 
bent due to space restrictions. 



Now the doubts: 



What impedance can I expect at the feed point with this configuration? 



How to match it in order to feed it with a 50 ohm cable? Some pages say 
that no match is required, only a choke. Other pages say a hairpin is 
necessary as the impedance can be too low. So other say that a tuner at the 
base is required? I am confused L 



What performance for DX can be achieved by this antenna? Is it really good 
or do you have some better suggestion for a really small lot where no ground 
radials are possible? 



Would it be worth to use a higher fiberglass pole, let's say 4 m (13 ft) 
higher, in order to lengthen the vertical section of the L? Would the 
difference be noticeable? 



Anyone has real experience setting up this antenna with elevated radials? 
Most information I can find on Internet is related to ground mounted 
antennas. 



Thanks in advance! 



73. Gabriel - EA6VQ 



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Re: Topband: Inverted L with elevated radials for topband

[Jim Brown]

On 3/5/2020 11:26 AM, Mike Waters wrote:

Many hams --including myself-- have had very good results using only a few
elevated radials.


Yes. One of the key factors is the height of the radials. N6BT, who has 
done a LOT of work with elevated radials on topband, told me that 18 ft 
is a minimum height. After my first tower (120 ft) was up, I had sloping 
wires rigged to points about 60 ft from the tower base, insulated from 
the tower and fed from the base against elevated radials. The tower has 
about ten on-ground radials to improves its performance as a reflector.


I had started out based on Rudy's early work with much lower elevation 
and wasn't satisfied with the result -- I had directivity, but the gain 
was poor. When I raised them to 18=20 ft (gull wing from about 3 ft at 
the feedpoint), I started seeing the few dB of gain that NEC predicted.


A few other important points. The ends of the radials are a high voltage 
point, so must be carefully insulated. Second, Rudy emphasizes that four 
elevated radials is a minimum, and twice that number is better. He also 
observes that they work better if current distribution between them is 
equal, that current distribution can be varied by variations in the soil 
underneath them, and that cutting them slightly shorter than a quarter 
wave minimizes those variations.


These are slides for a talk I've given about 160M antennas and 
counterpoise/radial systems, all based on good work by others.


http://k9yc.com/160MPacificon.pdf

73, Jim K9YC


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Re: Topband: Inverted L with elevated radials for topband

[Grant Saviers]

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 experience.

As noted by others, N6LF has a wealth of modeled and measured data on 
elevated radials.antennasbyn6lf.com




The antenna would be supported by a 16 m (52.5 ft) high fiberglass pole
placed on top of a 3m (10 ft) high small tower with the horizontal part of
the L slopping down to a 5 m (16 ft) high mast about 23 m (75 ft) away.  Two
to four tuned elevated radials can be placed, although they will have to be
bent due to space restrictions.


By "tuned" do you mean resonant 130ft +/-?  Again N6LF has data for 2 to 
16 elevated radials, and with more they can be shorter.
Also see his paper in Antenna Compendium 8 re inductively loading for 
shorter radials.  I had only 2 75ft radials on a 52' mast.


Now the doubts:

  


What impedance can I expect at the feed point with this configuration?

Having the radials as high as possible will minimize ground losses and 
decease Z.  With 2x at 10ft plan on 25 to 30 ohms.
  


How to match it in order to feed it with a 50 ohm cable?  Some pages say
that no match is required, only a choke. Other pages say a hairpin is
necessary as the impedance can be too low. So other say that a tuner at the
base is required?I am confused L


SWR losses on 160 are so low that a 2:1 doesn't cost many db's.  Too 
keep your amplifier happier I use a 50::25 ohm transmission line 
transformer.  make it or buy it.


A good choke is a must.  Make the K9YC 4" #31 choke.



What performance for DX can be achieved by this antenna?  Is it really good
or do you have some better suggestion for a really small lot where no ground
radials are possible?

You won't do better with anything else.  More radials will improve it 
slightly.
  


Would it be worth to use a higher fiberglass pole, let's say 4 m (13 ft)
higher, in order to lengthen the vertical section of the L?  Would the
difference be noticeable?



The taller the better but probably less than 1 db gain.



Anyone has real experience setting up this antenna with elevated radials?
Most information I can find on Internet is related to ground mounted
antennas.


Read all of what Rudy N6LF says, and you will be an expert.

Grant KZ1W




  


Thanks in advance!

  


73. Gabriel - EA6VQ

  


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Re: Topband: Inverted L with elevated radials for topband

[Mike Waters]

My experience too, Bill!

The very first time I tried my inverted-L with the two elevated radials
etc., I broke a  number of pile-ups in a contest with 100 watts! At that
time, I did not have an amplifier that covered 160m.

After that, for awhile I made a game out of turning down the power output
to 50 watts or less. I finally understood why some hams love QRP. :-)

73, Mike
W0BTU

On Thu, Mar 5, 2020, 2:13 PM Bill Stewart  wrote:

> ...
> These comments will be of little help as far as the technical info on the
> subject antenna and is a far cry from an excellently constructed antenna
> but it is very practicalin my opinion of course.
>
> However, I do use an Inv. L with a four wire counterpoise...or elevated
> radials if you prefer. Mine is approximately 50ft vertical and rest
> horiztotal, a quarter wave. The horizontal part is about 50 feet high
> and fairly flat. The antenna is completely covered over with tall pine
> trees. The CP wires go off from the base/feed point 10ft off the ground and
> at approximately 90 degrees apart. Each CP wire is about ten feet high and
> some are supported on tree trunks ... I only run 100 watts(CW) on 160no
> need for big coax in my case.  I have had very good success with this
> antenna. With 100 watts I have been able
> to work several DXped. stns in the Pacific, JA. This season I have worked
> nearly 80 EU, Carib and Pac. stations. I had a lot of fun in the recent
> ARRL CW test. ...
> Try iteasy to put up and if it don't work, go on to something
> elsehi.
> GL & 73 de Bill K4JYS/NC
>
>
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Re: Topband: Inverted L with elevated radials for topband

[pa5mw--- via Topband]

Hi Gabriel,

There is too many variables in your antenna setup to determine the expected 
impedance.

I have built and measured several inverted L's with/without elevated radials 
and/or sloping top wires.
So I will refrain from putting out estimations, other than guesses from what I 
learned during the last 30yrs.


What I do know:

Fact: an inverted L with 1/8 vertical and 1/8  straight  horizontal offers a 
radiation resistance  Rs=18 Ohm. No more.

Fact:  Antenna impedance (Z)= Rs+Rg.   Rground refers to energy not radiated 
but lost in the radials to ground. 

Your Antenna Analyzer/VNA will offer at resonance (find the frequency at which 
Xc=0) is Z.  You now have two unknown variables(Rs and Rg) and one measured 
value Z 

Fact: Z, SWR_usable_Bandwidth, Rground, Rs and any device to match it all to 50 
Ohm are variables which can be a challenge. But don't sweat it.

Fact: making the vertical part higher v.s. sloping wire=> get the sloping wire 
up. That is much more effective. 

My experience:

- A straight horizontal L-part is just to about impossible; at 1/8 length any 
wire will droop in the middle and lower Rs substantially. Spent two days 
measuring just that when I had two 23m HD tubular towers.
-  A sloping single top wire quickly lowers the Rs. In your setup I would 
expect it to be between 11 and 13 Ohm

- knowing that guestimated value; when your analyzer shows Z=40 Ohm SWR=great 
at resonance (Xc=0) one can calculate the ground losses Rg=40-12=28Ohm. That 
will be with 4 radials on ground probably. A nice SWR but effectivity is  
12/40= 30%  the other 28/40-70% of the power goes into ground.

- Good SWR does not mean the antenna is 'really good'. But don't seat it, 
sometimes you have limited options. And you have to start somewhere.

- Elevated radials: been there. 4 resonant elevated radials is possible, but 
difficult to measure correctly such that all four behave similar. We had  them 
at 4m height. Higher is better, more is better.

- If you lengthen the L-part so the total becomes 50 to 54m and tune out that 
extra length using a series Cap at the feedpoint, you can raise the Z. We did 
it with our 4 elevated radials and got a Z=34 Ohms which was nice to use a 
W2FMI 32:50 Ohm transformer.

- Radials; put down about 30-50pcs with 25 to max 30m length.  Want to lower 
Rground more effectively? Go to 120 radials at longer lengths, OR
-  Additionally put lengths of chicken wire directly under the vertical. Do not 
try to make length in a start config like radials; instead just closely cover 
straight lengths, make a square. It does not have to make electrical contact 
(it will help a bit but not the effort worth). Been there, measured it.

- At a good setup you probably will have a Z= 12+15=27 Ohms  (there it is I did 
make an estimation!) my point here:

- You will need a matching device / transformer (one toroid <500W, two or three 
at 1K5) to get from the guestimation value to connect it to your 50 Ohms coax 
feeder into the shack.

- There will be many other voices from other people having 
less/similar/more/different experience. 


My tips:

- Don't sweat it. At 1/8 vertical part, even with a sloping wire, one can make 
a good signal. Even at some crooked elevated radials.

- Read Low Band Dx'ing by ON4UN; it tells you how to do it, both in KISS mode 
as well as freaking nerd-mode. There will not be a great difference unless you 
have the hardware AND lots of real estate.

- Use an antenna analyzer which shows Xc, Z and SWR; the cheapest Rig Expert or 
any like is best in the field (no MFJ). I have had several different ones in 
the past 20yrs.

- Use a portable VNA if you must, but only if you have the experience how to 
use it. Or have someone come over to do that .  No Smith chart crap; that's 
for nerds and NOT effective in the field, unless you use smith charts on a 
daily basis.

- Measure at the antenna, using a pigtail coax to about 0,5 to  1m length. Yes 
one can measure it in the shack using professional network analyzers/ VNA's 
etc.  when the feedline is properly calibrated out. Been there. A friend has a 
large HP in his shack.  In the end we prefer that small but very practical Rig 
Expert.


Happy experimenting!

73
 Mark, PA5MW


-Original Message-
From: Topband  On Behalf Of 
Gabriel - EA6VQ via Topband
Sent: Thursday, March 05, 2020 19:02 PM
To: topband@contesting.com
Subject: Topband: Inverted L with elevated radials for topband

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 experience.

 

The antenna would be supported by a 16 m (52.5 ft) high fiberglass pole placed 
on top of a 3m (10 ft) high small tower with the horizontal part of the L 
slopping down to a 5 m (16 ft) high mast about 23 m (75 ft) away.  Two to four 
tuned elevated radials can be placed, al

Re: Topband: Inverted L with elevated radials for topband

[Bill Stewart]

Hi Gabriel,
These comments will be of little help as far as the technical info on the 
subject antenna
and is a far cry from an excellently constructed antenna but it is very 
practicalin my
opinion of course.

However, I do use an Inv. L with a four wire counterpoise...or elevated radials 
if you
prefer. Mine is approximately 50ft vertical and rest horiztotal, a quarter 
wave. The
horizontal part is about 50 feet high and fairly flat. The antenna is 
completely covered 
over with tall pine trees. The CP wires go off from the base/feed point 10ft 
off the ground
and at approximately 90 degrees apart. Each CP wire is about ten feet high and 
some are 
supported on tree trunks, others have some PVC posts for support and seems the 
CP wire
lengths are a bit shorter than a 1/4 wave lgth, but my memory may not be too 
good on this
part. I feed it with RG8X...I only run 100 watts(CW) on 160no need for big 
coax in my 
case. I just used a door-knob cap between the vert and CP at the basecan't 
remember the
value but think I just experimented until I got the SWR goodalso think I 
did some trimming
on the CP wires. I have had very good success with this antenna. With 100 watts 
I have been able
to work several DXped. stns in the Pacific, JA. This season I have worked 
nearly 80 EU, Carib
and Pac. stations. I had a lot of fun in the recent ARRL CW test. No, I don't 
get every station
I call, but enough to keep me happy. The purist, with all their instruments and 
computer
programs would laugh at my version, but it seems to be an easy antenna to get 
working and,
at least in my case, a decent antenna. (I also use it for receiving...works 
well there too).
Try iteasy to put up and if it don't work, go on to something elsehi.
GL & 73 de Bill K4JYS/NC

- Original Message -
From: "topband" 
To: "topband" 
Sent: Thursday, March 5, 2020 1:02:07 PM
Subject: Topband: Inverted L with elevated radials for topband

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 experience.

 

The antenna would be supported by a 16 m (52.5 ft) high fiberglass pole
placed on top of a 3m (10 ft) high small tower with the horizontal part of
the L slopping down to a 5 m (16 ft) high mast about 23 m (75 ft) away.  Two
to four tuned elevated radials can be placed, although they will have to be
bent due to space restrictions.

 

Now the doubts:

 

What impedance can I expect at the feed point with this configuration?

 

How to match it in order to feed it with a 50 ohm cable?  Some pages say
that no match is required, only a choke. Other pages say a hairpin is
necessary as the impedance can be too low. So other say that a tuner at the
base is required?I am confused L

 

What performance for DX can be achieved by this antenna?  Is it really good
or do you have some better suggestion for a really small lot where no ground
radials are possible?

 

Would it be worth to use a higher fiberglass pole, let's say 4 m (13 ft)
higher, in order to lengthen the vertical section of the L?  Would the
difference be noticeable?

 

Anyone has real experience setting up this antenna with elevated radials?
Most information I can find on Internet is related to ground mounted
antennas.

 

Thanks in advance!

 

73. Gabriel - EA6VQ

 

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Re: Topband: Inverted L with elevated radials for topband

[Mike Waters]

Many hams --including myself-- have had very good results using only a few
elevated radials.

This question contains an answer with a NEC 4.2 plot comparing the
efficiency of earth vs. elevated radials:
https://ham.stackexchange.com/questions/9823/how-does-the-performance-of-elevated-radials-differ-from-that-of-buried-radials

From the publications of N6LF (Dr. Rudy Severns) and others, they can be
almost the same. Please scroll past the table and graphs down to the
"Relevant links" section at
https://web.archive.org/web/20180815154501/http://w0btu.com/Optimum_number_of_ground_radials_vs_radial_length.html
 and you can read more proof.

However, *you cannot ground the elevated radials,* AND *you must use a
proper ferrite choke balun on the coax feedline right at the antenna
feedpoint*.
At
https://web.archive.org/web/20170703105635/http://www.w0btu.com/160_meters.html
scroll down to the section "The W0BTU 160 Meter Inverted-L Antenna" for
very important details about how to use elevated radials effectively.

One missing detail there is that these are "gull-wing" radials. That is,
they slope up at a 45° angle from the feedpoint to 10'.
Sorry there are no photos there.

73, Mike
W0BTU

On Thu, Mar 5, 2020, 12:12 PM Gabriel - EA6VQ via Topband <
topband@contesting.com> 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 experience.
>
_
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Topband: Inverted L with elevated radials for topband

[Gabriel - EA6VQ via Topband]

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 experience.

 

The antenna would be supported by a 16 m (52.5 ft) high fiberglass pole
placed on top of a 3m (10 ft) high small tower with the horizontal part of
the L slopping down to a 5 m (16 ft) high mast about 23 m (75 ft) away.  Two
to four tuned elevated radials can be placed, although they will have to be
bent due to space restrictions.

 

Now the doubts:

 

What impedance can I expect at the feed point with this configuration?

 

How to match it in order to feed it with a 50 ohm cable?  Some pages say
that no match is required, only a choke. Other pages say a hairpin is
necessary as the impedance can be too low. So other say that a tuner at the
base is required?I am confused L

 

What performance for DX can be achieved by this antenna?  Is it really good
or do you have some better suggestion for a really small lot where no ground
radials are possible?

 

Would it be worth to use a higher fiberglass pole, let's say 4 m (13 ft)
higher, in order to lengthen the vertical section of the L?  Would the
difference be noticeable?

 

Anyone has real experience setting up this antenna with elevated radials?
Most information I can find on Internet is related to ground mounted
antennas.

 

Thanks in advance!

 

73. Gabriel - EA6VQ

 

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Re: Topband: Inverted L and the High Angle Field

[Mike Waters]

Thanks for clarifying that. I didn't mention that because I thought it was
so obvious.

Also, the 5th edition of *Low Band DXing* is in favor of the T over the
inverted-L.

73, Mike
W0BTU

On Sat, Feb 29, 2020, 2:33 PM Jim Brown  wrote:

> ...  depends on the relative lengths of the horizontal and vertical
> sections. ...
>
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Topband: Inverted L and the High Angle Field

[Jim Brown]

On 2/29/2020 9:56 AM, Guy Olinger K2AV wrote:

Have to disagree on the no-use-for the horizontal leg.

It fills in the doughnut hole in the high angle radiation, which in
contests is very good for keeping others from planting on your run
frequency. Also there are high angle path opportunities that are gradually
becoming more recognized.


This effect is not nearly as great as generally believed, and depends on 
the relative lengths of the horizontal and vertical sections. For 
example, consider an L with 70 ft and 70 ft sections, as compared to 100 
ft vertical and 35 ft horizontal. the difference in field at 70 degrees 
elevation between the two antennas is 4 dB over Sandy soil, 3 dB over 
Very Good soil. For 50 ft vertical and 80 ft horizontal, the difference 
is 4 dB over very good soil as compared to 100 vertical, 35 horizontal. 
The reason for the difference, of course, is the current distribution 
between the two sections depending on their electrical length.


Comparing a T with 50 ft vertical and 55 ft horizontal to an L with 50 
ft vertical and 85 ft horizontal over Very Good soil, the difference is 
also 4 dB.


These differences are less than an S-unit, hardly enough to prevent 
someone poaching a run frequency. Propagation for shorter distances 
corresponding to a higher wave angle are covered by ground wave on 160M.


The way ARRL and NEC plot vertical patterns can be deceiving, because 
they always set the peak of the pattern to full scale. To see the 
difference, one must plot both antennas with the same scale. In NEC, 
this is accomplished by modeling each antenna, displaying the vertical 
pattern and saving the traces, then recalling the saved trace for the 
other antenna and selecting the recalled trace. The cursor can then be 
moved along the vertical axis and will display the difference in dB 
between the traces.


There are many examples of this technique in
http://k9yc.com/AntennaPlanning.pdf

A shorter vertical sections reduces the radiation resistance, which 
increases losses in the counterpoise/radial system, which in turn 
strongly depend upon soil quality.


73, Jim K9YC
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Re: Topband: inverted-L

[Clive GM3POI]

Pete the simplest method is to shorten the resonance of the antenna before 
adding the shunt to around 1.9mhz. Then use a variable L to find the correct 
value. Measure its inductance and replace it with a fixed value of the same. 
Job done. 73 Clive GM3POI

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of N4ZR
Sent: 04 September 2019 01:29
To: topband reflector
Subject: Topband: inverted-L

Thanks to everyone who responded to my message - lots of good ideas.  I 
think my favorite was the one about tapping a shunt coil from both ends, 
alternately, to bring both the radiation resistance and the resonant 
frequency in line.

-- 

73, Pete N4ZR
Check out the Reverse Beacon Network
at <http://reversebeacon.net>, now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

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Re: Topband: Inverted L redux

[donovanf]

Hi Pete, 


Unless you're planning more than 30 radials eventually, there's no reason 
to install radials longer than the 50-60 feet you're already using. 


This is one of several classic references on the topic. See 
see Figure 3 and the 160 meter column in Table X: 


https://ncjweb.com/bonus-content/k3lcmaxgainradials.pdf 


73 
Frank 
W3LPL 

- Original Message -

From: "N4ZR"  
To: "topband reflector"  
Sent: Monday, September 2, 2019 7:08:16 PM 
Subject: Topband: Inverted L redux 

More as an experiment and a thought-provoker than anything else, I've 
started adding 50-60-foot, on-the-ground radials to my 135-foot inverted 
L. In the latest incarnation I'm up to 4 radials. On my ancient 
MFJ-259B the lowest SWR is 1.3:1 at 1825 KHz, with an R of 77. X=0 (the 
259B doesn't give the sign of j) from 1808 to1894, which I assume is 
roughly centered on the actual cross-over point. 

With my rudimentary knowledge of such things, I'm guessing that there 
remains something on the order of 50 ohms of ground resistance to be 
reduced for efficiency, through addition of radials. Question is, 
would I profit most by adding another 4 50-60 foot radials, or 2 radials 
each 100-120 feet? 

Comments appreciated. 


-- 

73, Pete N4ZR 
Check out the Reverse Beacon Network 
at <http://reversebeacon.net>, now 
spotting RTTY activity worldwide. 
For spots, please use your favorite 
"retail" DX cluster. 

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Re: Topband: Inverted L redux

[S57AD]

Add more short (50 - 60 foot) radials, IMHO.  Some 45 years ago I worked as
a wireless operator in fixed service on 60m band (my call has been 4NC24L)
and we used L antennas. At my surprise, ground was just 3' of galvanized
pipe knocked into the ground. At company's electrician workshop I got heap
of scrap insulated copper wire different lengths which I used to lay down
some 40 or 50 radials different lengths, (in a half circle due to building
in which we were located). My signal improved so much net control asked me
what I was done and was asked to travel to another stations to install
radial systems there as well...

73, Mirko, S57AD

V V pon., 2. sep. 2019 ob 21:08 je oseba N4ZR  napisala:

> More as an experiment and a thought-provoker than anything else, I've
> started adding 50-60-foot, on-the-ground radials to my 135-foot inverted
> L.  In the latest incarnation I'm up to 4 radials.  On my ancient
> MFJ-259B the lowest SWR is 1.3:1 at 1825 KHz, with an R of 77. X=0 (the
> 259B doesn't give the sign of j) from 1808 to1894, which I assume is
> roughly centered on the actual cross-over point.
>
> With my rudimentary knowledge of such things, I'm guessing that there
> remains something on the order of 50 ohms of ground resistance to be
> reduced for efficiency,  through addition of radials.  Question is,
> would I profit most by adding another 4 50-60 foot radials, or 2 radials
> each 100-120 feet?
>
> Comments appreciated.
>
>
> --
>
> 73, Pete N4ZR
> Check out the Reverse Beacon Network
> at , now
> spotting RTTY activity worldwide.
> For spots, please use your favorite
> "retail" DX cluster.
>
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
>


-- 
Mirko S57AD
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Re: Topband: Inverted L redux

[Wes]

Four 50-60 footers.

See: https://www.antennasbyn6lf.com/files/antenna_ground_system_experiment_4.pdf 
for my rational.


Wes  N7WS

On 9/2/2019 12:08 PM, N4ZR wrote:
More as an experiment and a thought-provoker than anything else, I've started 
adding 50-60-foot, on-the-ground radials to my 135-foot inverted L.  In the 
latest incarnation I'm up to 4 radials.  On my ancient MFJ-259B the lowest SWR 
is 1.3:1 at 1825 KHz, with an R of 77. X=0 (the 259B doesn't give the sign of 
j) from 1808 to1894, which I assume is roughly centered on the actual 
cross-over point.


With my rudimentary knowledge of such things, I'm guessing that there remains 
something on the order of 50 ohms of ground resistance to be reduced for 
efficiency,  through addition of radials.  Question is, would I profit most by 
adding another 4 50-60 foot radials, or 2 radials each 100-120 feet?


Comments appreciated.




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Topband: Inverted L redux

[Clive GM3POI]

The bandwidth of the SWR is a clue to how poor the ground system is. As you
add radials the bandwidth will get narrower and the SWR is likely to change.
At present it all looks like a big dummy load. When you think you have added
enough radials double it again and measure parameters again.

73 Clive GM3POI

-Original Message-

From: Topband [ <mailto:topband-boun...@contesting.com>
mailto:topband-boun...@contesting.com] On Behalf Of N4ZR

Sent: 02 September 2019 19:08

To: topband reflector

Subject: Topband: Inverted L redux

More as an experiment and a thought-provoker than anything else, I've
started adding 50-60-foot, on-the-ground radials to my 135-foot inverted L.
In the latest incarnation I'm up to 4 radials.  On my ancient MFJ-259B the
lowest SWR is 1.3:1 at 1825 KHz, with an R of 77. X=0 (the 259B doesn't give
the sign of j) from 1808 to1894, which I assume is roughly centered on the
actual cross-over point.

With my rudimentary knowledge of such things, I'm guessing that there
remains something on the order of 50 ohms of ground resistance to be reduced
for efficiency,  through addition of radials.  Question is, would I profit
most by adding another 4 50-60 foot radials, or 2 radials each 100-120 feet?

Comments appreciated.


-- 

73, Pete N4ZR

Check out the Reverse Beacon Network

at < <http://reversebeacon.net> http://reversebeacon.net>, now

spotting RTTY activity worldwide.

For spots, please use your favorite

"retail" DX cluster.

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Re: Topband: Inverted L redux

[Richard (Rick) Karlquist]

On 9/2/2019 12:08 PM, N4ZR wrote:
More as an experiment and a thought-provoker than anything else, I've 
started adding 50-60-foot, on-the-ground radials to my 135-foot inverted 
L.  In the latest incarnation I'm up to 4 radials.  On my ancient 
MFJ-259B the lowest SWR is 1.3:1 at 1825 KHz, with an R of 77. X=0 (the 


The radiation resistance depends somewhat on the vertical vs horizontal
components of the 135 feet which you didn't specify.  It is easy to
model on EZNEC what the drive impedance is over ideal ground then you
can compare that to what you are measuring to determine ground 
resistance.  I suspect most of your 77 ohms is in the antenna, not

ground.  So you probably don't need a huge radial field.

The problem with inverted L's is that a lot of the drive impedance
represents useless horizontally polarized energy.  If you want to make
it better, change to T top loading.

Rick N6RK
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Re: Topband: Inverted L redux

[rgarrett5]

Pete,

Traditional wisdom is, if you have the choice of short or long radials, more 
shorter ones are preferred over a few long ones.  However, 50 60 foot radials 
are not considered long for 160 meters.  I have found that 50 to 60 radials 
will do a great job.  At least 30 is a good starting point.  73, Bob K3UL  

-Original Message-
From: Topband  On Behalf Of N4ZR
Sent: Monday, September 2, 2019 3:08 PM
To: topband reflector 
Subject: Topband: Inverted L redux

More as an experiment and a thought-provoker than anything else, I've started 
adding 50-60-foot, on-the-ground radials to my 135-foot inverted L.  In the 
latest incarnation I'm up to 4 radials.  On my ancient MFJ-259B the lowest SWR 
is 1.3:1 at 1825 KHz, with an R of 77. X=0 (the 259B doesn't give the sign of 
j) from 1808 to1894, which I assume is roughly centered on the actual 
cross-over point.

With my rudimentary knowledge of such things, I'm guessing that there remains 
something on the order of 50 ohms of ground resistance to be reduced for 
efficiency,  through addition of radials.  Question is, would I profit most by 
adding another 4 50-60 foot radials, or 2 radials each 100-120 feet?

Comments appreciated.


-- 

73, Pete N4ZR
Check out the Reverse Beacon Network
at <http://reversebeacon.net>, now
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Re: Topband: inverted l

[Rob Atkinson]

If you have a properly constructed typical inverted L, i.e. 50 or 60
foot vertical and similar length horizontal, AND a good ground system
serving as the other half of the antenna, your feedpoint Z will be 10
to 20 ohms.  The reason you need a matching network is that most coax
(this assumes you are feeding the antenna with a coaxial transmission
line) has a characteristic impedance of 50 ohms or more.  If you found
coax with a characteristic Z of 15 ohms you probably wouldn't need a
matching network.  Let's say you don't bother with a network.  Your
line will have voltage maxima and current maxima on it and exhibit
more loss but it may be okay depending on the line used and its
length.  The other problem is whether or not your transmitter has an
output network that can handle the other than 50 ohms Z it will see at
the end of the line with this arrangement.  If all of this is a
problem for one reason or another, you need a matching network.   With
antennas that have feedpoints near the ground, you can place it at the
feedpoint which is nice.   Any inverted L with an adequate ground
system, elevated or buried, will have a pretty narrow impedance
bandwidth for matching purposes.  Anything that exhibits a fairly flat
bandwidth, say 50 or more kc, is probably not radiating efficiently.
You can improve this, but the way to do it is to widen the width of
the driven element, for example instead of using a single wire, employ
a cage.

You can raise the impedance of the L by increasing the vertical
length.  Eventually with 1/4 wave length vertical, the ideal Z will be
around 36 ohms, but then it ceases to be an inverted L.

73
Rob
K5UJ
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Re: Topband: inverted l

[Michael Walker]

Hi Doug

Ignore those splitting hairs.  :)

Yes, and inverted L will represent a load that should work for your radio
without any additional tuners (should).

I run an inverted L right up the side of an 80 ft pine tree and then I have
4 elevated radials.  2 of those radials parallel a fence that surrounds a
Tennis court.  Not much I can do about it.  The horizontal part goes over
to another tree.  Many say the fence will detune the antenna, but I don't
see it and it closely resembles the numbers when I plugged them into AO
(Antenna Optimizer).

To prevent the winds from tearing it apart, I have about 30ft of UV protect
shock cord on the rest of the horizontal part before the line heads down
the other support tree.  Since I added the 1/4" shock cord, I have not had
a fracture in the antenna.  In the past, when it did fracture, I had to
take the Quad Copter out and re-drop a new line.  :)

My antenna is NOT SWR flat across the entire band, which is good.  The
flatter the SWR you have the more ground losses and less radiated signal.
I forgot what  my 2:1 SWR bandwidth is, but it is about 1800khz to 1905 or
so.  It depends if the ground is frozen or not.

I've worked the world on this antenna.  Short story, I highly recommend you
build it and try it.  If it works, awesome.  If it doesn't try something
else.  It is just wire and you can re-use it.   If you get this shortly
after I right this, you can look at my PSK Report Link for FT8 and see what
parts of the world I was heard in tonight even with the solar storm.
https://pskreporter.info/pskmap.html?preset=va3mw=60-300=86400

I hope that helps, Mike va3mw

On Sun, Sep 1, 2019 at 9:20 PM K9FD  wrote:

> Matching network does not resonate the antenna
>
>
> > Guys
> > Will a invereted L a quarter wave length resonate at a given frequency
> without a matching network?
> > Doug wd8z
> > Sent from Mail for Windows 10
> >
> > _
> > Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
>
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Re: Topband: inverted l

[K9FD]

Matching network does not resonate the antenna



Guys
Will a invereted L a quarter wave length resonate at a given frequency without 
a matching network?
Doug wd8z
Sent from Mail for Windows 10

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Re: Topband: inverted l

[Wes]

Anything will resonate at some frequency.  The question should be will it be a 
good match at the desired frequency.


Wes  N7WS

On 9/1/2019 4:02 PM, doug dietz wrote:

Guys
Will a invereted L a quarter wave length resonate at a given frequency without 
a matching network?
Doug wd8z
Sent from Mail for Windows 10

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Topband: inverted l

[doug dietz]

Guys
Will a invereted L a quarter wave length resonate at a given frequency without 
a matching network?
Doug wd8z
Sent from Mail for Windows 10

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Re: Topband: Inverted L in contact with leaves

[Joe Galicic]

Hi Pete. My inverted L over K2AV FCP was in the trees touching limbs and 
leaves.  Although it worked OK it wasn't until I moved it into the clear that I 
realized how much signal I was loosing having it in the trees.  Nearly 3db 
increase according to RBN after the move.  RBN testing was done immediately 
before and after the move.  Of course this test is just a relative indicator 
but it did show a lot of improvement after the move.  I know Guy K2AV has done 
similar test with similar results.  -Joe N3HEE


> On August 29, 2019 at 11:23 AM N4ZR  wrote:
> 
> 
> My inverted L is taking shape - about 60 vertical, the rest horizontal.  
> For a couple of months anyway, it is touching a number of leaves in the 
> vertical section.  I assume that's not a concern, but thought I'd ask 
> before I get a lot of radials down. First short radial is down and 
> MFJ-259 results look promising.  It's just a problem of waiting for lawn 
> mowing to stop hi.
> 
> -- 
> 
> 73, Pete N4ZR
> Check out the Reverse Beacon Network
> at , now
> spotting RTTY activity worldwide.
> For spots, please use your favorite
> "retail" DX cluster.
> 
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Re: Topband: Inverted L in contact with leaves

[Mike Furrey]

 My inverted L with elevated radials has touched limbs and leaves and I have 
still gotten out well. SWR does change (but not appreciably) with the rise and 
fall of the tree sap and with rain (very wet tree). All were made of 14 gauge 
insulated wire from the big box hardware stores. The only issue (really excited 
the neighbors) occurred when a squirrel bit through the insulation at a high 
voltage point and the bare wire touched leaves. I had arcs and small flames 
occurring every time I hit the key.

73, Mike WA5POK


 On Thursday, August 29, 2019, 12:19:40 PM EDT, AB2E Darrell 
 wrote:  
 
 Hi Pete,
No effect noticed here for leaves with L wire running over tree.
I just reinstalled my 160m Inverted - L on a taller tree (fed 10ft off ground, 
80ft vertical , about 52ft horizontal). It's been up all summer with leaves, it 
goes over the top of 95ft oak. My vertical wire is #12 THHN, insulated solid 
copper. I have 5 tuned radials of the same wire, but thinner gauge is also OK. 
I feed it with a 1:1 Balun Designs balun. I trimmed it slightly but it 
resonates about 1845 and gives me all the CW band. Tested with Acom 2000A at 
1500W outseems very stable as before mounted on a  shorter tree at about 
65ft.

Pete, even 1 tuned radial for your L, you should see it working and loading up 
OK if you want to test.

I used to easily find the tech supplement online from Butternut for tuned 
radials, but it looks like it's now gone.
Check this document out 
https://rudys.typepad.com/files/elevated-ground-systems-article-final-version.pdf
 . N6LF did some modelling and looks very similar to ON4UN's conclusions in his 
lowband book that 4 tuned radials achieve 60% of the efficiency of 100+ radials 
on the ground. Some may dispute this, but I've never had enough real estate to 
put down a full ground radial field of 100+, but I do have room to put up 4 
elevated radials. They can slope, go up and down but if you can, mount them 
about 10ft above ground.
The tuned radials are about 3.5% shorter than the 1/4wave element (see the 
formula). I cut them all the same as the element, and then gradually shorten 
them to adjust for resonance, depending on how the SWR looks.

In the past, the L has worked great for me. I now have about 115 countries 
confirmed on 160, all with an L.

73 and best of luck with the project,
Darrell AB2E



From: Topband  on behalf of N4ZR 

Sent: Thursday, August 29, 2019 11:23 AM
To: topband reflector 
Subject: Topband: Inverted L in contact with leaves

My inverted L is taking shape - about 60 vertical, the rest horizontal.
For a couple of months anyway, it is touching a number of leaves in the
vertical section.  I assume that's not a concern, but thought I'd ask
before I get a lot of radials down. First short radial is down and
MFJ-259 results look promising.  It's just a problem of waiting for lawn
mowing to stop hi.

--

73, Pete N4ZR
Check out the Reverse Beacon Network
at <http://reversebeacon.net>, now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

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Re: Topband: Inverted L in contact with leaves

[Michael Walker]

Hi Pete

You won't have an issue at all.

73, Mike va3mw

On Thu, Aug 29, 2019 at 12:24 PM Gary Smith  wrote:

> I sure don't have any kind of superstation
> but I have never been lucky enough to have
> a 160 antenna in the clear. All mine have
> always not only touched leaves, but are
> always resting on branches, many branches.
> I still get out pretty well, I wouldn't
> worry about a few leaves coming in
> contact.
>
> 73,
>
> Gary
> KA1J
>
>
> > My inverted L is taking shape - about 60 vertical, the rest
> > horizontal.  For a couple of months anyway, it is touching a number
> > of leaves in the vertical section.  I assume that's not a concern,
> > but thought I'd ask before I get a lot of radials down. First short
> > radial is down and MFJ-259 results look promising.  It's just a
> > problem of waiting for lawn mowing to stop hi.
> >
> > --
> >
> > 73, Pete N4ZR
> > Check out the Reverse Beacon Network
> > at , now
> > spotting RTTY activity worldwide.
> > For spots, please use your favorite
> > "retail" DX cluster.
>
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
>
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Re: Topband: Inverted L in contact with leaves

[Gary Smith]

I sure don't have any kind of superstation 
but I have never been lucky enough to have 
a 160 antenna in the clear. All mine have 
always not only touched leaves, but are 
always resting on branches, many branches. 
I still get out pretty well, I wouldn't 
worry about a few leaves coming in 
contact.

73,

Gary
KA1J


> My inverted L is taking shape - about 60 vertical, the rest
> horizontal.  For a couple of months anyway, it is touching a number
> of leaves in the vertical section.  I assume that's not a concern,
> but thought I'd ask before I get a lot of radials down. First short
> radial is down and MFJ-259 results look promising.  It's just a
> problem of waiting for lawn mowing to stop hi.
> 
> -- 
> 
> 73, Pete N4ZR
> Check out the Reverse Beacon Network
> at , now
> spotting RTTY activity worldwide.
> For spots, please use your favorite
> "retail" DX cluster.

_
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Re: Topband: Inverted L in contact with leaves

[AB2E Darrell]

Hi Pete,
No effect noticed here for leaves with L wire running over tree.
I just reinstalled my 160m Inverted - L on a taller tree (fed 10ft off ground, 
80ft vertical , about 52ft horizontal). It's been up all summer with leaves, it 
goes over the top of 95ft oak. My vertical wire is #12 THHN, insulated solid 
copper. I have 5 tuned radials of the same wire, but thinner gauge is also OK. 
I feed it with a 1:1 Balun Designs balun. I trimmed it slightly but it 
resonates about 1845 and gives me all the CW band. Tested with Acom 2000A at 
1500W outseems very stable as before mounted on a  shorter tree at about 
65ft.

Pete, even 1 tuned radial for your L, you should see it working and loading up 
OK if you want to test.

I used to easily find the tech supplement online from Butternut for tuned 
radials, but it looks like it's now gone.
Check this document out 
https://rudys.typepad.com/files/elevated-ground-systems-article-final-version.pdf
 . N6LF did some modelling and looks very similar to ON4UN's conclusions in his 
lowband book that 4 tuned radials achieve 60% of the efficiency of 100+ radials 
on the ground. Some may dispute this, but I've never had enough real estate to 
put down a full ground radial field of 100+, but I do have room to put up 4 
elevated radials. They can slope, go up and down but if you can, mount them 
about 10ft above ground.
The tuned radials are about 3.5% shorter than the 1/4wave element (see the 
formula). I cut them all the same as the element, and then gradually shorten 
them to adjust for resonance, depending on how the SWR looks.

In the past, the L has worked great for me. I now have about 115 countries 
confirmed on 160, all with an L.

73 and best of luck with the project,
Darrell AB2E



From: Topband  on behalf of N4ZR 

Sent: Thursday, August 29, 2019 11:23 AM
To: topband reflector 
Subject: Topband: Inverted L in contact with leaves

My inverted L is taking shape - about 60 vertical, the rest horizontal.
For a couple of months anyway, it is touching a number of leaves in the
vertical section.  I assume that's not a concern, but thought I'd ask
before I get a lot of radials down. First short radial is down and
MFJ-259 results look promising.  It's just a problem of waiting for lawn
mowing to stop hi.

--

73, Pete N4ZR
Check out the Reverse Beacon Network
at <http://reversebeacon.net>, now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

_
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Topband: Inverted L in contact with leaves

[N4ZR]

My inverted L is taking shape - about 60 vertical, the rest horizontal.  
For a couple of months anyway, it is touching a number of leaves in the 
vertical section.  I assume that's not a concern, but thought I'd ask 
before I get a lot of radials down. First short radial is down and 
MFJ-259 results look promising.  It's just a problem of waiting for lawn 
mowing to stop hi.


--

73, Pete N4ZR
Check out the Reverse Beacon Network
at , now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

_
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Re: Topband: Inverted L - newbie questions

[N4ZR]

Jumper was 1 foot.

73, Pete N4ZR
Check out the Reverse Beacon Network
at , now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

On 8/21/2019 12:47 PM, WW3S wrote:

Where did you connect the analyzer? You want it as close as possible to the 
feed point, with as little length of coax jumper as possible. Even a 6 ft 
jumper can skew the results, been there done that

Sent from my iPad


On Aug 21, 2019, at 12:36 PM, Jeff Blaine  wrote:

An inverted L without radials is a random length wire and the measurements are 
of no meaning until there is a ground system to make up the other half of the 
antenna.

But to Wes point, the 259 and big 160m antennas is a recipe for going nuts.  
You don't even need a high powered BC station - even a low powered station a 
pretty far distance away can cause the 259 to give results in error.  A VNA or 
something like the Rig Expert are FAR more robust in this application.

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com



On 8/21/19 12:04 AM, Wes wrote:
How many high-powered BC stations do you have around?

Wes  N7WS


On 8/21/2019 8:55 AM, N4ZR wrote:
I just put up an inverted L, with a vertical length of about 60 feet, and a 
total of 135 feet.  It is fed through 16 turns of RG-400 on a ferrite core at 
the base. There are, as yet, no radials.

Because I was impatient to see what was going on, I grounded the shield to a 
single copper-plated ground rod and connected my MFJ259B. I expected a high R 
value, and I got one - 112-122 ohms. But surprisingly (to me), lowest SWR was 
at 2.070 MHz, and X remained at zero over quite a wide range - all the way down 
to about 1.7 MHz.

Is this all to be expected?  I plan to put down at least minimum radials in the 
next few days, and would expect the R value to drop as I do so. Am I off-base?


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Re: Topband: Inverted L - newbie questions

[WW3S]

Where did you connect the analyzer? You want it as close as possible to the 
feed point, with as little length of coax jumper as possible. Even a 6 ft 
jumper can skew the results, been there done that

Sent from my iPad

> On Aug 21, 2019, at 12:36 PM, Jeff Blaine  wrote:
> 
> An inverted L without radials is a random length wire and the measurements 
> are of no meaning until there is a ground system to make up the other half of 
> the antenna.
> 
> But to Wes point, the 259 and big 160m antennas is a recipe for going nuts.  
> You don't even need a high powered BC station - even a low powered station a 
> pretty far distance away can cause the 259 to give results in error.  A VNA 
> or something like the Rig Expert are FAR more robust in this application.
> 
> 73/jeff/ac0c
> alpha-charlie-zero-charlie
> www.ac0c.com
> 
> 
>> On 8/21/19 12:04 AM, Wes wrote:
>> How many high-powered BC stations do you have around?
>> 
>> Wes  N7WS
>> 
>>> On 8/21/2019 8:55 AM, N4ZR wrote:
>>> I just put up an inverted L, with a vertical length of about 60 feet, and a 
>>> total of 135 feet.  It is fed through 16 turns of RG-400 on a ferrite core 
>>> at the base. There are, as yet, no radials.
>>> 
>>> Because I was impatient to see what was going on, I grounded the shield to 
>>> a single copper-plated ground rod and connected my MFJ259B. I expected a 
>>> high R value, and I got one - 112-122 ohms. But surprisingly (to me), 
>>> lowest SWR was at 2.070 MHz, and X remained at zero over quite a wide range 
>>> - all the way down to about 1.7 MHz.
>>> 
>>> Is this all to be expected?  I plan to put down at least minimum radials in 
>>> the next few days, and would expect the R value to drop as I do so. Am I 
>>> off-base?
>>> 
>> 
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Re: Topband: Inverted L - newbie questions

[Jeff Blaine]

An inverted L without radials is a random length wire and the 
measurements are of no meaning until there is a ground system to make up 
the other half of the antenna.


But to Wes point, the 259 and big 160m antennas is a recipe for going 
nuts.  You don't even need a high powered BC station - even a low 
powered station a pretty far distance away can cause the 259 to give 
results in error.  A VNA or something like the Rig Expert are FAR more 
robust in this application.


73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com


On 8/21/19 12:04 AM, Wes wrote:

How many high-powered BC stations do you have around?

Wes  N7WS

On 8/21/2019 8:55 AM, N4ZR wrote:
I just put up an inverted L, with a vertical length of about 60 feet, 
and a total of 135 feet.  It is fed through 16 turns of RG-400 on a 
ferrite core at the base. There are, as yet, no radials.


Because I was impatient to see what was going on, I grounded the 
shield to a single copper-plated ground rod and connected my MFJ259B. 
I expected a high R value, and I got one - 112-122 ohms. But 
surprisingly (to me), lowest SWR was at 2.070 MHz, and X remained at 
zero over quite a wide range - all the way down to about 1.7 MHz.


Is this all to be expected?  I plan to put down at least minimum 
radials in the next few days, and would expect the R value to drop as 
I do so. Am I off-base?




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Reflector

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Re: Topband: Inverted L - newbie questions

[Wes]

How many high-powered BC stations do you have around?

Wes  N7WS

On 8/21/2019 8:55 AM, N4ZR wrote:
I just put up an inverted L, with a vertical length of about 60 feet, and a 
total of 135 feet.  It is fed through 16 turns of RG-400 on a ferrite core at 
the base. There are, as yet, no radials.


Because I was impatient to see what was going on, I grounded the shield to a 
single copper-plated ground rod and connected my MFJ259B. I expected a high R 
value, and I got one - 112-122 ohms. But surprisingly (to me), lowest SWR was 
at 2.070 MHz, and X remained at zero over quite a wide range - all the way 
down to about 1.7 MHz.


Is this all to be expected?  I plan to put down at least minimum radials in 
the next few days, and would expect the R value to drop as I do so. Am I 
off-base?




_
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Topband: Inverted L - newbie questions

[N4ZR]

I just put up an inverted L, with a vertical length of about 60 feet, 
and a total of 135 feet.  It is fed through 16 turns of RG-400 on a 
ferrite core at the base. There are, as yet, no radials.


Because I was impatient to see what was going on, I grounded the shield 
to a single copper-plated ground rod and connected my MFJ259B. I 
expected a high R value, and I got one - 112-122 ohms.  But surprisingly 
(to me), lowest SWR was at 2.070 MHz, and X remained at zero over quite 
a wide range - all the way down to about 1.7 MHz.


Is this all to be expected?  I plan to put down at least minimum radials 
in the next few days, and would expect the R value to drop as I do so. 
Am I off-base?


--

73, Pete N4ZR
Check out the Reverse Beacon Network
at , now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

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Re: Topband: Inverted L loading wire dilemma

[Clive GM3POI]

Dave,
I would use a different approach, try 2 sloping wires opposite each other of
the same length. They will cancel out the horizontal component of the
loading and give you an overall better signal. For about 20 years I used a
51ft vertical with two stainless steel loading wires (just capacity to
ground). Which netted 298 current DXCC.
I later changed it to a 60ft vertical with shorter loading wires. Both
systems used a Hairpin match. I must say I don't see much difference between
the 51' and 60' vertical, although my ground system is extremely good, so
would not expect too.  Both vertical heights here had the loading wire tips
at a height of about 35-45ft  
Dependent on version. All resonated at about 1.9mhz before the adding of the
hairpin coil.   DXCC current only confirmed is 308.
73 Clive GM3POI

-Original Message-
From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Dave
G4GED via Topband
Sent: 14 March 2019 20:06
To: topband@contesting.com
Subject: Topband: Inverted L loading wire dialmma

For many years my 160m antenna has been a very successful classic 21m 
tall Inv L mast with a horizontal loading wire.
The only problem, a big one, has been the loading wire getting tangled 
up in the surrounding trees in very windy weather.
Chopping the trees down is not an option and I've had enough of the agro 
of untangling, to be honest.
I know I could provide loading at the feed point but it's not as efficient.
So, I wondered if anyone have had success with providing the loading 
wire(s) at say 45deg from the mast top down to ground level? (Witches 
Hat style).
Thanks in advance for any advice.
Dave G4GED




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Re: Topband: Inverted L loading wire dialmma

[Herbert Schoenbohm]

The "witches hat" as you call it makes an excellent top loading medium for
Marconi antennas.  I use them here on an AM tower with great success in
improving the base impedance of a less than 1/4 tower. Care must be taken
that these angled down wires are not to long. (I think 30% of the antena
height is about maximum.  Use 4 or more wires if possible. Addionally good
insulators able to handle the very high RF voltage should be used.  Never
use rope or any medium that can accumulate moisture. In the DX Engineering
catalog is a version of the witches hat antenna for 160 using sloping guys
for the top hat. The price is USD$1000 but this model has been used on TB
for  several DX- peditions.  There are several other add ons you can try as
you may require.  Rather th.  Accrodingly, if you connect the top slop down
wires an using a single vertical drop wire or insulated pole, I would use a
4 wire cage made from 4-6 inchsquare sheets of plastic. Additinally, if you
connect all the slope down wires together from one to the other you will
make even a better capacity hat and improlve things.  If you measure your
base impedence against ground as you make these improvements, you should
see how things are progressing. But take care and make sure your ground
system is adequate or else you readings may be confusing.  For example you
might see 50 ohms and not realize that this value is the result of a poor
ground and a good po9rtion of your RF is thus dissapated rather than being
radiated.

Good luck,
Herb, KV4FZ

On Thu, Mar 14, 2019 at 5:11 PM Dave G4GED via Topband <
topband@contesting.com> wrote:

> For many years my 160m antenna has been a very successful classic 21m
> tall Inv L mast with a horizontal loading wire.
> The only problem, a big one, has been the loading wire getting tangled
> up in the surrounding trees in very windy weather.
> Chopping the trees down is not an option and I've had enough of the agro
> of untangling, to be honest.
> I know I could provide loading at the feed point but it's not as efficient.
> So, I wondered if anyone have had success with providing the loading
> wire(s) at say 45deg from the mast top down to ground level? (Witches
> Hat style).
> Thanks in advance for any advice.
> Dave G4GED
>
>
>
>
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Topband: Inverted L loading wire dialmma

[Dave G4GED via Topband]

For many years my 160m antenna has been a very successful classic 21m 
tall Inv L mast with a horizontal loading wire.
The only problem, a big one, has been the loading wire getting tangled 
up in the surrounding trees in very windy weather.
Chopping the trees down is not an option and I've had enough of the agro 
of untangling, to be honest.

I know I could provide loading at the feed point but it's not as efficient.
So, I wondered if anyone have had success with providing the loading 
wire(s) at say 45deg from the mast top down to ground level? (Witches 
Hat style).

Thanks in advance for any advice.
Dave G4GED




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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Tim Shoppa]

Todd, have you been tracking your antenna system's performance using
reversebeacon after your sunset?

I'm guessing that your sunset is circa 0300Z.

Last night (Jan 24) you were picked up at 9 western skimmers, perhaps the
furthest ones from you being WB6BEE and the VE6's.

Based on my experience, that this would be expected performance for a good
160M transmit antenna at 5W level on a quiet night. (I certainly don't have
a TX 4-square but I've been in top 10 of several 160M contests). As a
cross-comparison on Tuesday night I was CQ'ing at 5W in the NAQCC 160M
Sprint from my W3 location, and I was picked up by skimmers all over the
east coast and by a few in 9-land and 0-land.

Now a small skimmer data set is not the best way in the world to get
absolute antenna performance results. But with some caveats, A/B
comparisons (using same receiver site at nearby times and frequencies) are
possible between two of your own antennas, or between your station and a
nearby station.

http://reversebeacon.net/dxsd1/dxsd1.php?f=0=nr7rr=dx

N7TUG NR7RR 1826.0 CW CQ [LoTW] 12 dB 20 wpm 0859z 24 Jan
VE6WZ NR7RR 1826.0 CW CQ [LoTW] 24 dB 20 wpm 0859z 24 Jan
VE6JY NR7RR 1826.0 CW CQ [LoTW] 31 dB 20 wpm 0859z 24 Jan
K2PO-7 NR7RR 1826.0 CW CQ [LoTW] 18 dB 20 wpm 0859z 24 Jan
WA7LNW NR7RR 1826.0 CW CQ [LoTW] 19 dB 20 wpm 0859z 24 Jan
WB6BEE NR7RR 1826.0 CW CQ [LoTW] 13 dB 20 wpm 0859z 24 Jan
N7TR NR7RR 1826.0 CW CQ [LoTW] 25 dB 20 wpm 0859z 24 Jan
N6TV NR7RR 1817.0 CW CQ [LoTW] 6 dB 20 wpm 0856z 24 Jan
N7TUG NR7RR 1816.0 CW CQ [LoTW] 11 dB 20 wpm 0706z 24 Jan
N6TV NR7RR 1816.0 CW CQ [LoTW] 8 dB 20 wpm 0705z 24 Jan
NC7J NR7RR 1824.0 CW CQ [LoTW] 5 dB 20 wpm 0328z 24 Jan

Tim N3QE

>
>
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Joe]

How about even lay it down?

Joe WB9SBD
Sig
The Original Rolling Ball Clock
Idle Tyme
Idle-Tyme.com
http://www.idle-tyme.com
On 1/23/2019 7:14 PM, Jeff Blaine wrote:

Disconnect the other antenna.  Let it float.

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com

On 23-Jan-19 6:02 PM, Todd Goins wrote:
Okay, after many requests, on and off list, I disconnected the 43' T 
160m

antenna at its feed point and for good measure I disconnected the coax
feedline from the system too.

It made a pretty substantial difference in the measurements. The 1.5 SWR
range is now only about 35 kHz wide but the 2.0 SWR range is still 
100 kHz

which is probably still too wide.

Freq  SWR  R    X Z
1800 1.9 31.8  -18.6 36.8
1810 1.7 32.5  -14.1 35.4
1820 1.6 33.3  -9.6  34.7
1830 1.5 33.9  -5.3  34.3
1840 1.45 34.6  -0.7  34.6
1850 1.43 35.5  3.9  35.7
1860 1.47 36.1  9.0  37.2
1870 1.6 37.0  13.9  39.5
1880 1.7 37.8  18.9  42.3
1890 1.8 38.8  24.0  45.6
1900 2 39.9  29.5  49.6
1910 2.2 41.1  34.5  53.7
1920 2.4 42.6  40.5  58.8
1940 2.8 44.7  51.4  68.1
1960 3.4 47.6  63.0  78.9

I'll test it on the air tonight (using FT-8 and the RBN) with the 43'
antenna disconnected. Perhaps it will be better? The numbers look 
better,

right?

Should I ground the 43' antenna instead of leaving it floating?

Thanks guys.
73,
Todd - NR7RR
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Jeff Blaine]

Disconnect the other antenna.  Let it float.

73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com

On 23-Jan-19 6:02 PM, Todd Goins wrote:

Okay, after many requests, on and off list, I disconnected the 43' T 160m
antenna at its feed point and for good measure I disconnected the coax
feedline from the system too.

It made a pretty substantial difference in the measurements. The 1.5 SWR
range is now only about 35 kHz wide but the 2.0 SWR range is still 100 kHz
which is probably still too wide.

Freq  SWR  RX Z
1800 1.9 31.8  -18.6 36.8
1810 1.7 32.5  -14.1 35.4
1820 1.6 33.3  -9.6  34.7
1830 1.5 33.9  -5.3  34.3
1840 1.45 34.6  -0.7  34.6
1850 1.43 35.5  3.9  35.7
1860 1.47 36.1  9.0  37.2
1870 1.6 37.0  13.9  39.5
1880 1.7 37.8  18.9  42.3
1890 1.8 38.8  24.0  45.6
1900 2 39.9  29.5  49.6
1910 2.2 41.1  34.5  53.7
1920 2.4 42.6  40.5  58.8
1940 2.8 44.7  51.4  68.1
1960 3.4 47.6  63.0  78.9

I'll test it on the air tonight (using FT-8 and the RBN) with the 43'
antenna disconnected. Perhaps it will be better? The numbers look better,
right?

Should I ground the 43' antenna instead of leaving it floating?

Thanks guys.
73,
Todd - NR7RR
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Todd Goins]

Okay, after many requests, on and off list, I disconnected the 43' T 160m
antenna at its feed point and for good measure I disconnected the coax
feedline from the system too.

It made a pretty substantial difference in the measurements. The 1.5 SWR
range is now only about 35 kHz wide but the 2.0 SWR range is still 100 kHz
which is probably still too wide.

Freq  SWR  RX Z
1800 1.9 31.8  -18.6 36.8
1810 1.7 32.5  -14.1 35.4
1820 1.6 33.3  -9.6  34.7
1830 1.5 33.9  -5.3  34.3
1840 1.45 34.6  -0.7  34.6
1850 1.43 35.5  3.9  35.7
1860 1.47 36.1  9.0  37.2
1870 1.6 37.0  13.9  39.5
1880 1.7 37.8  18.9  42.3
1890 1.8 38.8  24.0  45.6
1900 2 39.9  29.5  49.6
1910 2.2 41.1  34.5  53.7
1920 2.4 42.6  40.5  58.8
1940 2.8 44.7  51.4  68.1
1960 3.4 47.6  63.0  78.9

I'll test it on the air tonight (using FT-8 and the RBN) with the 43'
antenna disconnected. Perhaps it will be better? The numbers look better,
right?

Should I ground the 43' antenna instead of leaving it floating?

Thanks guys.
73,
Todd - NR7RR
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[K9FD]

Dont get discouraged by all this for sure

What I see as fly in the ointment is another 160 antenna close by with 
another

radial system,
Anyone of you gurus ever figure what putting power into a 160 antenna does
with another one within feet of it?   Imagine power going out, and right 
back

into the other one,  being burned up in loss..
Its like having a parasitic element sitting there and screwing up your 
entire

attempts.
Wonder why the SWR is broad,  your tuning two antennas,  any one who has
ever tried to tune a 4 square with all elements up knows it cannot be done
actually.

Take down the short 160 antenna or find a way to detune it far far from 
160,

and then take some measurements.

Come on expurts look at the whole picture not be tunnel visioned,

73 Merv K9FD

Both Merv and Guy are correct here. Perhaps this antenna doesn't ever
have a chance at being any good due to the suburban area and lot size
that I'm constrained by.

Within a 250ft radius (huge!) there is as follows: 80m dipole, 40m
dipole, 30m dipole, 20m dipole, 15m dipole, 20m yagi, and the original
43' tall T antenna for 160m and its radial system. Also, the house is
easily within 250ft.  Most certainly the radial systems, although not
physically connected to each other, are let's say "mingling".

So perhaps this tall wire was doomed from the outset? I was so
encouraged that the 43' T worked so well for what it was and the small
amount of effort it took to get converted to 160m that maybe a taller
version would be substantially better. That's how this saga started.
Maybe the real answer after time/effort/money expended and all of your
advise is that it isn't going to get any better in my environment?

At this point the best path forward may be to just remove the tall
wire and reroute all of the new radials (over 2000ft) to the original
43' T's radial plate and with any luck make it play better as a
result?

Todd - NR7RR



Way back some where around the original posting did he not say he had
2 160 antennas up and they are close to each other?  a short vertical and
this antenna?   If so what is the short vertical doing,  is it floating or
grounded or hooked to the ground system yet,  what is its status?
Would make all the difference in the world if the short 160 vertical is
any where around yet.

73 Merv K9FD
* Have to pay attention to everything he is reporting. He added a feedpoint

*>* choke per K9YC at the same time. Which may, depending on the physical
*>* connections at his feedpoint, have removed the feedline shield as an
*>* alternate “radial” in parallel with the increasing but still not full size
*>* radial system.
*>>* That indicates that his ground characteristics could be well into the
*>* “poor” end of the range where ground radial deficiencies are multiplied and
*>* emphasized.
*>>* His SWR bandwidth narrowed slightly. Leaving a strong possibility that
*>* there was an improvement in desired radiated pattern.
*>>* There remains the question of every conductor in a 250 foot radius,
*>* including a tower? There remains the question of large dielectric masses
*>* close by.
*>>* 73, Guy K2AV
*

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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Wes]

As always Frank makes good points.  In my case my one lowly tower is 90 feet 
from the inverted-L and in fact supports the horizontal wire.  It's much too 
short to exhibit any resonance near topband, but I have observed an interesting 
effect.


The tower also supports a pair of inverted-vee dipoles, fed in parallel, one for 
40 the other for 80.  With a vector analyzer I can sweep the inverted-L and 
looking at the trace on a Smith chart and see a little discontinuity around 1.8 
MHz that goes away if I lower the vee to the ground or terminate the shack end 
of the coax.  It's a really minor effect and apparent;y not even an intellectual 
curiosity as I've not bothered to investigate it further.  It does point out 
however, that "detuning" by leaving things open circuit isn't necessarily the 
way to go.


Wes  N7WS

On 1/23/2019 3:45 PM, donov...@starpower.net wrote:

Hi Todd,


In my opinion you're giving up too easily on your tall antenna.
I suggest that you focus more on evaluating its on-the-air performance ,
and not focus as intently its feed point impedance and VSWR bandwidth.


I hope you've been measuring the impedance and bandwidth
of your tall antenna with your 43 foot vertical disconnecte d from
its both its 160 meter matching components and its feed line,
otherwise it will interact very strongly with your tall antenna.


Very few of us have the opportunity to install our 160 meter
antennas a thousand feet or more from other antennas and tall
towers. As a result, the feed point impedance and other characteristics
of our antennas can't possibly match theoretical values. Nonetheless,
we enjoy our imperfect antennas with their imperfect soil conditions.


I hope you'll enjoy yours too.


73
Frank
W3LPL



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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Mike Smith VE9AA]

Hey Todd, 

 

What happens to your Inverted L's SWR curve if you short your other 160m
antenna (the 43'-T) to ground, or otherwise detune it somehow?..could be
you're onto something..not sure. Wide SWR's like that generally point to
huge ground losses.

 

I just can't get over how freeging wide your SWR curve *(and frankly I am a
little surprised more folks haven't weighed in on this thread)

 

Mike VE9AA

 

 

NR7RR:



So perhaps this tall wire was doomed from the outset? I was so

encouraged that the 43' T worked so well for what it was and the small

amount of effort it took to get converted to 160m that maybe a taller

version would be substantially better

 

At this point the best path forward may be to just remove the tall

wire and reroute all of the new radials (over 2000ft) to the original

43' T's radial plate and with any luck make it play better as a

result?

 

Todd - NR7RR

 

 

Mike, Coreen & Corey

Keswick Ridge, NB

 

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Re: Topband: Inverted L improvements - Part 3 (now with data)

[donovanf]

Hi Todd, 


In my opinion you're giving up too easily on your tall antenna. 
I suggest that you focus more on evaluating its on-the-air performance , 
and not focus as intently its feed point impedance and VSWR bandwidth. 


I hope you've been measuring the impedance and bandwidth 
of your tall antenna with your 43 foot vertical disconnecte d from 
its both its 160 meter matching components and its feed line, 
otherwise it will interact very strongly with your tall antenna. 


Very few of us have the opportunity to install our 160 meter 
antennas a thousand feet or more from other antennas and tall 
towers. As a result, the feed point impedance and other characteristics 
of our antennas can't possibly match theoretical values. Nonetheless, 
we enjoy our imperfect antennas with their imperfect soil conditions. 


I hope you'll enjoy yours too. 


73 
Frank 
W3LPL 

- Original Message -

From: "Todd Goins"  
To: topband@contesting.com, 676a8e87-aec6-9ead-1297-0bdb1f0a7...@gmail.com 
Sent: Wednesday, January 23, 2019 9:09:19 PM 
Subject: Re: Topband: Inverted L improvements - Part 3 (now with data) 

Both Merv and Guy are correct here. Perhaps this antenna doesn't ever 
have a chance at being any good due to the suburban area and lot size 
that I'm constrained by. 

Within a 250ft radius (huge!) there is as follows: 80m dipole, 40m 
dipole, 30m dipole, 20m dipole, 15m dipole, 20m yagi, and the original 
43' tall T antenna for 160m and its radial system. Also, the house is 
easily within 250ft. Most certainly the radial systems, although not 
physically connected to each other, are let's say "mingling". 

So perhaps this tall wire was doomed from the outset? I was so 
encouraged that the 43' T worked so well for what it was and the small 
amount of effort it took to get converted to 160m that maybe a taller 
version would be substantially better. That's how this saga started. 
Maybe the real answer after time/effort/money expended and all of your 
advise is that it isn't going to get any better in my environment? 

At this point the best path forward may be to just remove the tall 
wire and reroute all of the new radials (over 2000ft) to the original 
43' T's radial plate and with any luck make it play better as a 
result? 

Todd - NR7RR 


>Way back some where around the original posting did he not say he had 
>2 160 antennas up and they are close to each other? a short vertical and 
>this antenna? If so what is the short vertical doing, is it floating or 
>grounded or hooked to the ground system yet, what is its status? 
>Would make all the difference in the world if the short 160 vertical is 
>any where around yet. 
> 
>73 Merv K9FD 

>* Have to pay attention to everything he is reporting. He added a feedpoint 
*>* choke per K9YC at the same time. Which may, depending on the physical 
*>* connections at his feedpoint, have removed the feedline shield as an 
*>* alternate “radial” in parallel with the increasing but still not full size 
*>* radial system. 
*>>* That indicates that his ground characteristics could be well into the 
*>* “poor” end of the range where ground radial deficiencies are multiplied and 
*>* emphasized. 
*>>* His SWR bandwidth narrowed slightly. Leaving a strong possibility that 
*>* there was an improvement in desired radiated pattern. 
*>>* There remains the question of every conductor in a 250 foot radius, 
*>* including a tower? There remains the question of large dielectric masses 
*>* close by. 
*>>* 73, Guy K2AV 
* 

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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Jeff Blaine]

I worked 160m for a few years when living in a townhome.  The antenna 
was a trap loaded attic mounted dipole that ran through holes in the 
ceiling and down the walls to the ground.  Had a lot of 160m contest fun 
with that.  Worked all the devices in the house as well until I was able 
to get enough pounds of ferrite on everything electronic.


So having some kind of outdoor antenna with some kind of ground by 
comparison, you will do just fine.  Don't worry about how you rack up to 
the ideal.  Just do the best you can and get on the air!


73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com

On 23-Jan-19 3:21 PM, Jamie WW3S wrote:
Todd, don’t get discouraged and don’t let lot size fool youI'm in 
a subdivision, 80x180 ft lot, with a 50ft tower, hygain hytower for 
75/80m (also works as a second radio antenna), and 2L 40m phased 
array...my inv l is suspended off the top of the towerI never 
modeled it, I just know it works.DXCC on 160 with low 
power.now that I added an amp, I'm up to 140+ worked.the 
secret on 160 is receiving, which really hampers me.forgot the 
modeling for a minute, did you try the reverse beacon thing I 
mentioned a few days ago.that will tell you if you are getting out 
or not.btw, my L is 135 ft (at least it was when it started, I 
lost a few feet due to some weather related issues)..about 50 ft 
vertical, then the rest  mostly horizontal to a tall tree in the 
woods


-Original Message- From: Todd Goins
Sent: Wednesday, January 23, 2019 4:09 PM
To: topband@contesting.com ; 
676a8e87-aec6-9ead-1297-0bdb1f0a7...@gmail.com

Subject: Re: Topband: Inverted L improvements - Part 3 (now with data)

Both Merv and Guy are correct here. Perhaps this antenna doesn't ever
have a chance at being any good due to the suburban area and lot size
that I'm constrained by.

Within a 250ft radius (huge!) there is as follows: 80m dipole, 40m
dipole, 30m dipole, 20m dipole, 15m dipole, 20m yagi, and the original
43' tall T antenna for 160m and its radial system. Also, the house is
easily within 250ft.  Most certainly the radial systems, although not
physically connected to each other, are let's say "mingling".

So perhaps this tall wire was doomed from the outset? I was so
encouraged that the 43' T worked so well for what it was and the small
amount of effort it took to get converted to 160m that maybe a taller
version would be substantially better. That's how this saga started.
Maybe the real answer after time/effort/money expended and all of your
advise is that it isn't going to get any better in my environment?

At this point the best path forward may be to just remove the tall
wire and reroute all of the new radials (over 2000ft) to the original
43' T's radial plate and with any luck make it play better as a
result?

Todd - NR7RR



Way back some where around the original posting did he not say he had
2 160 antennas up and they are close to each other?  a short vertical 
and
this antenna?   If so what is the short vertical doing,  is it 
floating or

grounded or hooked to the ground system yet,  what is its status?
Would make all the difference in the world if the short 160 vertical is
any where around yet.

73 Merv K9FD


* Have to pay attention to everything he is reporting. He added a 
feedpoint

*>* choke per K9YC at the same time. Which may, depending on the physical
*>* connections at his feedpoint, have removed the feedline shield as an
*>* alternate “radial” in parallel with the increasing but still not 
full size

*>* radial system.
*>>* That indicates that his ground characteristics could be well into 
the
*>* “poor” end of the range where ground radial deficiencies are 
multiplied and

*>* emphasized.
*>>* His SWR bandwidth narrowed slightly. Leaving a strong possibility 
that

*>* there was an improvement in desired radiated pattern.
*>>* There remains the question of every conductor in a 250 foot radius,
*>* including a tower? There remains the question of large dielectric 
masses

*>* close by.
*>>* 73, Guy K2AV
*

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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Mike Waters]

Spooks! Haunted soil! ;-)
That's probably not the problem.

As I mentioned privately, I think uploading some more photos to a free
file-sharing service website *and sharing those links here* would help us
all to help you solve this.

Since photo attachments to the Topband Reflector are not possible, can
anyone recommend a good file sharing website that Todd (and others) could
use?

73, Mike
www.w0btu.com

On Wed, Jan 23, 2019, 2:48 PM Todd Goins  wrote:

> Regarding the choke construction and implementation. Mike and I have had an
> offline exchange, with pictures, and I think we have agreed that the choke
> has been constructed properly per the newest K9YC specifications using a
> 2.4" Type 31 Fair-Rite toroid and 18 turns of RG400.
>
> Also, the 150' long coax feedline has never been attached while taking any
> measurements. At least not any reported here. All of the recent data (taken
> with the RigExpert analyzer) I've put in tables in postings has been while
> being connected to the output of a choke. The feedline was not part of the
> equation.  The coax stubs coming off of the choke are only a couple of
> inches long on each end. The body of the RigExpert is plastic and it
> doesn't seem to matter whether or not I'm holding it but I do take the
> "official" measurements with it sitting on a towel on the ground. I did
> also take measurements with a 4' coax jumper between the choke output and
> the analyzer just to get the analyzer clear of the radial attachment area.
> This made no appreciable difference in the measured values.
>
> At this point the "antenna erected over haunted burial ground" theory is
> sounding more and more plausible.
>
> Hope to catch lots of you guys, hey and maybe some DX too, on the 160
> contest this weekend.
>
> 73,
> Todd - NR7RR
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Jamie WW3S]

Todd, don’t get discouraged and don’t let lot size fool youI'm in a 
subdivision, 80x180 ft lot, with a 50ft tower, hygain hytower for 75/80m 
(also works as a second radio antenna), and 2L 40m phased array...my inv l 
is suspended off the top of the towerI never modeled it, I just know it 
works.DXCC on 160 with low power.now that I added an amp, I'm up to 
140+ worked.the secret on 160 is receiving, which really hampers 
me.forgot the modeling for a minute, did you try the reverse beacon 
thing I mentioned a few days ago.that will tell you if you are getting 
out or not.btw, my L is 135 ft (at least it was when it started, I lost 
a few feet due to some weather related issues)..about 50 ft vertical, 
then the rest  mostly horizontal to a tall tree in the woods


-Original Message- 
From: Todd Goins

Sent: Wednesday, January 23, 2019 4:09 PM
To: topband@contesting.com ; 676a8e87-aec6-9ead-1297-0bdb1f0a7...@gmail.com
Subject: Re: Topband: Inverted L improvements - Part 3 (now with data)

Both Merv and Guy are correct here. Perhaps this antenna doesn't ever
have a chance at being any good due to the suburban area and lot size
that I'm constrained by.

Within a 250ft radius (huge!) there is as follows: 80m dipole, 40m
dipole, 30m dipole, 20m dipole, 15m dipole, 20m yagi, and the original
43' tall T antenna for 160m and its radial system. Also, the house is
easily within 250ft.  Most certainly the radial systems, although not
physically connected to each other, are let's say "mingling".

So perhaps this tall wire was doomed from the outset? I was so
encouraged that the 43' T worked so well for what it was and the small
amount of effort it took to get converted to 160m that maybe a taller
version would be substantially better. That's how this saga started.
Maybe the real answer after time/effort/money expended and all of your
advise is that it isn't going to get any better in my environment?

At this point the best path forward may be to just remove the tall
wire and reroute all of the new radials (over 2000ft) to the original
43' T's radial plate and with any luck make it play better as a
result?

Todd - NR7RR



Way back some where around the original posting did he not say he had
2 160 antennas up and they are close to each other?  a short vertical and
this antenna?   If so what is the short vertical doing,  is it floating or
grounded or hooked to the ground system yet,  what is its status?
Would make all the difference in the world if the short 160 vertical is
any where around yet.

73 Merv K9FD



* Have to pay attention to everything he is reporting. He added a feedpoint

*>* choke per K9YC at the same time. Which may, depending on the physical
*>* connections at his feedpoint, have removed the feedline shield as an
*>* alternate “radial” in parallel with the increasing but still not full 
size

*>* radial system.
*>>* That indicates that his ground characteristics could be well into the
*>* “poor” end of the range where ground radial deficiencies are multiplied 
and

*>* emphasized.
*>>* His SWR bandwidth narrowed slightly. Leaving a strong possibility that
*>* there was an improvement in desired radiated pattern.
*>>* There remains the question of every conductor in a 250 foot radius,
*>* including a tower? There remains the question of large dielectric masses
*>* close by.
*>>* 73, Guy K2AV
*

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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Todd Goins]

Both Merv and Guy are correct here. Perhaps this antenna doesn't ever
have a chance at being any good due to the suburban area and lot size
that I'm constrained by.

Within a 250ft radius (huge!) there is as follows: 80m dipole, 40m
dipole, 30m dipole, 20m dipole, 15m dipole, 20m yagi, and the original
43' tall T antenna for 160m and its radial system. Also, the house is
easily within 250ft.  Most certainly the radial systems, although not
physically connected to each other, are let's say "mingling".

So perhaps this tall wire was doomed from the outset? I was so
encouraged that the 43' T worked so well for what it was and the small
amount of effort it took to get converted to 160m that maybe a taller
version would be substantially better. That's how this saga started.
Maybe the real answer after time/effort/money expended and all of your
advise is that it isn't going to get any better in my environment?

At this point the best path forward may be to just remove the tall
wire and reroute all of the new radials (over 2000ft) to the original
43' T's radial plate and with any luck make it play better as a
result?

Todd - NR7RR


>Way back some where around the original posting did he not say he had
>2 160 antennas up and they are close to each other?  a short vertical and
>this antenna?   If so what is the short vertical doing,  is it floating or
>grounded or hooked to the ground system yet,  what is its status?
>Would make all the difference in the world if the short 160 vertical is
>any where around yet.
>
>73 Merv K9FD

>* Have to pay attention to everything he is reporting. He added a feedpoint
*>* choke per K9YC at the same time. Which may, depending on the physical
*>* connections at his feedpoint, have removed the feedline shield as an
*>* alternate “radial” in parallel with the increasing but still not full size
*>* radial system.
*>>* That indicates that his ground characteristics could be well into the
*>* “poor” end of the range where ground radial deficiencies are multiplied and
*>* emphasized.
*>>* His SWR bandwidth narrowed slightly. Leaving a strong possibility that
*>* there was an improvement in desired radiated pattern.
*>>* There remains the question of every conductor in a 250 foot radius,
*>* including a tower? There remains the question of large dielectric masses
*>* close by.
*>>* 73, Guy K2AV
*

--
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Todd Goins]

Regarding the choke construction and implementation. Mike and I have had an
offline exchange, with pictures, and I think we have agreed that the choke
has been constructed properly per the newest K9YC specifications using a
2.4" Type 31 Fair-Rite toroid and 18 turns of RG400.

Also, the 150' long coax feedline has never been attached while taking any
measurements. At least not any reported here. All of the recent data (taken
with the RigExpert analyzer) I've put in tables in postings has been while
being connected to the output of a choke. The feedline was not part of the
equation.  The coax stubs coming off of the choke are only a couple of
inches long on each end. The body of the RigExpert is plastic and it
doesn't seem to matter whether or not I'm holding it but I do take the
"official" measurements with it sitting on a towel on the ground. I did
also take measurements with a 4' coax jumper between the choke output and
the analyzer just to get the analyzer clear of the radial attachment area.
This made no appreciable difference in the measured values.

At this point the "antenna erected over haunted burial ground" theory is
sounding more and more plausible.

Hope to catch lots of you guys, hey and maybe some DX too, on the 160
contest this weekend.

73,
Todd - NR7RR
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Wes]

Your "apparent" and mine are different because it isn't apparent to me that I 
advocated that.  I offered a possible explanation to what Todd is observing and 
provided the title of a reference source where he could explore it more fully. I 
mentioned what I am using and my rational for doing so.


Wes  N7WS

On 1/22/2019 3:12 PM, Mike Smith VE9AA wrote:

So, now we're (apparently) recommending he cut back his already minimal
radial field..uhhh, really Wes?

  



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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Mike Waters]

It's possible that the K9YC choke was improperly wound, per my forwarded
message from Jim here yesterday. Here is K9YC's updated info on choke
baluns.
http://k9yc.com/2018Cookbook.pdf

73, Mike
www.w0btu.com

On Wed, Jan 23, 2019, 1:05 AM Guy Olinger K2AV  wrote:

> ...
> He inserted a K9YC design choke at feedpoint and his R went up, indicating
> that the earlier measurement was lowered by something shunting down the
> true R of the radials.
> ...
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Guy Olinger K2AV]

What is missing from that discussion about a maximized use of a given
investment, is whether that investment however well maximized, is in fact
adequate for the particular ground characteristics and circumstances.

Four rotten eggs will deliver a rotten omelette no matter what you mix in
or how neatly it’s served up.

In seriously poor ground, the total copper in the radials needs to be
enough for full size, dense and uniform all around. A maximized inadequate
is still inadequate.

Sparse, undersized, or irregular ground radials do not do it for poor
ground.

His results with shorter radials suspiciously point to poor ground or
perhaps a local loss issue not yet identified.

He inserted a K9YC design choke at feedpoint and his R went up, indicating
that the earlier measurement was lowered by something shunting down the
true R of the radials.

73, Guy K2AV

On Tue, Jan 22, 2019 at 10:31 PM Chortek, Robert L. <
robert.chor...@berliner.com> wrote:

> Exactly!
>
> Sent from my iPhone
>
> > On Jan 22, 2019, at 7:25 PM, Grant Saviers  wrote:
> >
> > 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 height (see
> N6LF
> >>> reference).  He didn't reduce the number of radials.”
> >> I didn’t think it was the “shortening” OF the length of the radials
> that would improve performance e.g. going from 10 125’ radials to 10 55’
> radials (in the case of a 55’ vertical); rather, it was the fact that 10x
> 125’ of wire could be better employed to increase the number of radials,
> albeit resulting in shorter radials, that decreases the ground loss (since
> most is nearer the base of the vertical).  If I’m correct, then shortening
> a given number of radials should decrease loss or improve performance
> >> 73,
> >> Bob AA6VB
> >> _
> >> Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
>
-- 
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Chortek, Robert L.]

Exactly!

Sent from my iPhone

> On Jan 22, 2019, at 7:25 PM, Grant Saviers  wrote:
> 
> 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 height (see N6LF
>>> reference).  He didn't reduce the number of radials.”
>> I didn’t think it was the “shortening” OF the length of the radials that 
>> would improve performance e.g. going from 10 125’ radials to 10 55’ radials 
>> (in the case of a 55’ vertical); rather, it was the fact that 10x 125’ of 
>> wire could be better employed to increase the number of radials, albeit 
>> resulting in shorter radials, that decreases the ground loss (since most is 
>> nearer the base of the vertical).  If I’m correct, then shortening a given 
>> number of radials should decrease loss or improve performance
>> 73,
>> Bob AA6VB
>> _
>> Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Grant Saviers]

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 height (see N6LF

reference).  He didn't reduce the number of radials.”


I didn’t think it was the “shortening” OF the length of the radials that would 
improve performance e.g. going from 10 125’ radials to 10 55’ radials (in the 
case of a 55’ vertical); rather, it was the fact that 10x 125’ of wire could be 
better employed to increase the number of radials, albeit resulting in shorter 
radials, that decreases the ground loss (since most is nearer the base of the 
vertical).  If I’m correct, then shortening a given number of radials should 
decrease loss or improve performance

73,

Bob AA6VB
_
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Chortek, Robert L.]

Meant to say “should not decrease loss ...”

Sorry!

Bob AA6VB 

Sent from my iPhone

> On Jan 22, 2019, at 4:11 PM, Chortek, Robert L.  
> wrote:
> 
> “Wes cut his radial length to match the vertical L section height (see N6LF
>> reference).  He didn't reduce the number of radials.”
> 
> I didn’t think it was the “shortening” OF the length of the radials that 
> would improve performance e.g. going from 10 125’ radials to 10 55’ radials 
> (in the case of a 55’ vertical); rather, it was the fact that 10x 125’ of 
> wire could be better employed to increase the number of radials, albeit 
> resulting in shorter radials, that decreases the ground loss (since most is 
> nearer the base of the vertical).  If I’m correct, then shortening a given 
> number of radials should decrease loss or improve performance
> 
> 73,
> 
> Bob AA6VB
_
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[K9FD]

Way back some where around the original posting did he not say he had
2 160 antennas up and they are close to each other?  a short vertical and
this antenna?   If so what is the short vertical doing,  is it floating or
grounded or hooked to the ground system yet,  what is its status?
Would make all the difference in the world if the short 160 vertical is
any where around yet.

73 Merv K9FD

Have to pay attention to everything he is reporting. He added a feedpoint
choke per K9YC at the same time. Which may, depending on the physical
connections at his feedpoint, have removed the feedline shield as an
alternate “radial” in parallel with the increasing but still not full size
radial system.

That indicates that his ground characteristics could be well into the
“poor” end of the range where ground radial deficiencies are multiplied and
emphasized.

His SWR bandwidth narrowed slightly. Leaving a strong possibility that
there was an improvement in desired radiated pattern.

There remains the question of every conductor in a 250 foot radius,
including a tower? There remains the question of large dielectric masses
close by.

73, Guy K2AV


_
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Chortek, Robert L.]

“Wes cut his radial length to match the vertical L section height (see N6LF
> reference).  He didn't reduce the number of radials.”

I didn’t think it was the “shortening” OF the length of the radials that would 
improve performance e.g. going from 10 125’ radials to 10 55’ radials (in the 
case of a 55’ vertical); rather, it was the fact that 10x 125’ of wire could be 
better employed to increase the number of radials, albeit resulting in shorter 
radials, that decreases the ground loss (since most is nearer the base of the 
vertical).  If I’m correct, then shortening a given number of radials should 
decrease loss or improve performance

73,

Bob AA6VB 
_
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Paul Christensen]

>So, now we're (apparently) recommending he cut back his already minimal
radial field..uhhh, really Wes?

I agree with Wes' assessment -- as well as him questioning why Rr would
increase with an increased number of radials.  If Rr is changing
significantly with the increase, then something else is perturbing the
measurement.  

Wes cut his radial length to match the vertical L section height (see N6LF
reference).  He didn't reduce the number of radials.  

Paul, W9AC 

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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Mike Smith VE9AA]

So, now we're (apparently) recommending he cut back his already minimal
radial field..uhhh, really Wes?

 

=-Mike VE9AA

 

I started this message a day or so ago.  Others have commented since with
some similar thoughts, nevertheless, here is my take. 

 

Todd you're going the wrong direction. The feed point resistance should be
going down. 

 

A 1/4 wave wire vertical should have a radiation resistance(Rr) of around 35
ohm. Ignoring conductor loss, over a perfect (zero ohm) ground, the feed
point resistance is also ~35 ohm.  The Rr of a shortened, top loaded
vertical (inverted-L) will be lower than that, the shorter, the lower.
Ground loss resistance (Rg) that appears in series with the Rr increases the
feed point resistance to Rr + Rg, assuming resonance.  Rg also lowers Q. 

 

Since your total feed point resistance is increasing, as is BW, you must
have increased Rg.  Although this seems counter-intuitive, experiments have
shown that, on or in, the ground radials can be too long.  See:  "Vertical
antenna ground system experiment No. 4" by N6LF. 

 

For my inverted L, I cut my insulated-on-the-ground radials to 55' because
1) that's the height of the vertical part of the L; 2) it gives me 9 radials
with no waste from a 500' roll of wire and 3) that's the longest length I
can use and still maintain symmetry.  I recently measured the Z of one of
these against the rest of the ground system with a network analyzer and by
serendipity found it resonant at ~1.9 MHz. 

 

At the moment I have only 12 radials, although I plan more (see my QRZ page
to see why I haven't rushed into this).  Around resonance, a Smith chart
display of a model of the antenna feed point Z overlays nearly identically
the measured Z, if I add 13 ohm simulated ground resistance to the model.
That is the apparent ground loss. 

Wes  N7WS

 

 

Mike, Coreen & Corey

Keswick Ridge, NB

 

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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Guy Olinger K2AV]

Have to pay attention to everything he is reporting. He added a feedpoint
choke per K9YC at the same time. Which may, depending on the physical
connections at his feedpoint, have removed the feedline shield as an
alternate “radial” in parallel with the increasing but still not full size
radial system.

That indicates that his ground characteristics could be well into the
“poor” end of the range where ground radial deficiencies are multiplied and
emphasized.

His SWR bandwidth narrowed slightly. Leaving a strong possibility that
there was an improvement in desired radiated pattern.

There remains the question of every conductor in a 250 foot radius,
including a tower? There remains the question of large dielectric masses
close by.

73, Guy K2AV
-- 
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Wes]

On 1/22/2019 8:03 AM, Bruce wrote:
You maybe confusing "Radiation Resistance" with "Feed point Resistance". It 
often will lower "Feed point Resistance", but raise "radiation Resistance".


Really?  Why?

Wes  N7WS

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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Wes]

I started this message a day or so ago.  Others have commented since with some 
similar thoughts, nevertheless, here is my take.


Todd you're going the wrong direction. The feed point resistance should be going 
down.


A 1/4 wave wire vertical should have a radiation resistance(Rr) of around 35 
ohm. Ignoring conductor loss, over a perfect (zero ohm) ground, the feed point 
resistance is also ~35 ohm.  The Rr of a shortened, top loaded vertical 
(inverted-L) will be lower than that, the shorter, the lower. Ground loss 
resistance (Rg) that appears in series with the Rr increases the feed point 
resistance to Rr + Rg, assuming resonance.  Rg also lowers Q.


Since your total feed point resistance is increasing, as is BW, you must have 
increased Rg.  Although this seems counter-intuitive, experiments have shown 
that, on or in, the ground radials can be too long.  See:  "Vertical antenna 
ground system experiment No. 4" by N6LF.


For my inverted L, I cut my insulated-on-the-ground radials to 55' because 1) 
that's the height of the vertical part of the L; 2) it gives me 9 radials with 
no waste from a 500' roll of wire and 3) that's the longest length I can use and 
still maintain symmetry.  I recently measured the Z of one of these against the 
rest of the ground system with a network analyzer and by serendipity found it 
resonant at ~1.9 MHz.


At the moment I have only 12 radials, although I plan more (see my QRZ page to 
see why I haven't rushed into this).  Around resonance, a Smith chart display of 
a model of the antenna feed point Z overlays nearly identically the measured Z, 
if I add 13 ohm simulated ground resistance to the model.  That is the apparent 
ground loss.


Wes  N7WS

On 1/21/2019 6:45 PM, Todd Goins wrote:

Hello,

Per many people's recommendations I added 800ft of radials today. That is 8
x 100ft each.  It made a difference on the analyzer which I'll summarize
below. It was dark when I finished but here are a few data points. I think
it is better. The wide SWR curve still bothers me but the resistance is
coming up.

This is also using the new K9YC cookbook choke with 18 turns of RG400
around a 2.4" type 31 toroid.

The values are Freq, SWR, R, X, Z

1810  1.43  42.0  -14.5  44.5
1820  1.31  43.2  -10.7  44.5
1830  1.21  44.1  -6.7   44.7
1840  1.13  45.0  -2.5   45.1
1850  1.10  45.9  1.7   45.9
1860  1.14  47.0  5.7  47.3
1870  1.23  48.0  10.1  49.1
1880  1.34  49.1  14.7  51.2

Any thoughts?  The 160 CW contest is only 4 days away, I don't have a lot
more time to make changes but I could run a "few" more radials...

73,
Todd - NR7RR
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Peter Bertini]

Indeed, that is what I meant to say.

On Tue, Jan 22, 2019 at 10:03 AM Bruce  wrote:

> You maybe confusing "Radiation Resistance" with "Feed point Resistance".
> It often will lower "Feed point Resistance", but raise "radiation
> Resistance". 73 Bruce
>
> On 1/22/2019 9:45 AM, Peter Bertini wrote:
> > I would think adding radials would lower the Radiation resistance.  Also,
> > the SWR curve should narrow as ground losses are reduced;  since the
> effect
> > of ground loss resistance swamping the results lessens.
> >
> > At some point I suggest, as others, that you get on for the contest and
> see
> > what you can do.  If you can run a bit of power, it will help.  Receiving
> > is indeed the tough nut to crack on 160 Meters.
> >
> > Elevated radials may be worth a shot. I think Mike uses two with good
> > results. I went to a K2AV FCP and it works good enough for my needs. Even
> > with a K9AY loop system receiving is still my weak point.
> >
> > Get on for the contests and have some fun.
> >
> > Pete
> > _
> > Searchable Archives: http://www.contesting.com/_topband - Topband
> Reflector
> >
>
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[GEORGE WALLNER]

Todd,
The resistive component should be going down with more radials, not up.
Maybe you are not measuring it the right way, or something in the radial 
system could be resonant (which may be a good thing).


Normally, with these antennas, lower R is better (less loss).

I have just measured a top loaded 57 foot tall vertical that stands in 
salt-water, which is an almost perfect ground. The feed point R is 8.5 Ohms. 
(Using an AIM-55 analyzer.)


Anyway, does your antenna get out? That is the ultimate test.

George,
AA7JV/C6AGU


On Mon, 21 Jan 2019 17:45:52 -0800
 Todd Goins  wrote:

Hello,

Per many people's recommendations I added 800ft of radials today. That is 8
x 100ft each.  It made a difference on the analyzer which I'll summarize
below. It was dark when I finished but here are a few data points. I think
it is better. The wide SWR curve still bothers me but the resistance is
coming up.

This is also using the new K9YC cookbook choke with 18 turns of RG400
around a 2.4" type 31 toroid.

The values are Freq, SWR, R, X, Z

1810  1.43  42.0  -14.5  44.5
1820  1.31  43.2  -10.7  44.5
1830  1.21  44.1  -6.7   44.7
1840  1.13  45.0  -2.5   45.1
1850  1.10  45.9  1.7   45.9
1860  1.14  47.0  5.7  47.3
1870  1.23  48.0  10.1  49.1
1880  1.34  49.1  14.7  51.2

Any thoughts?  The 160 CW contest is only 4 days away, I don't have a lot
more time to make changes but I could run a "few" more radials...

73,
Todd - NR7RR
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Paul Christensen]

>"I would think adding radials would lower the Radiation resistance.  Also,
the SWR curve should narrow as ground losses are reduced;  since the effect
of ground loss resistance swamping the results lessens."

The base resistance, not the radiation resistance is lowered by adding in
radials.  At resonance, the antenna's feed-point equivalent circuit is two
resistors in series:  Rr for the radiated component, and Rg for the loss
component.  By lowering Rg, efficiency increases and feed-point resistance
is reduced when additional radials are added.  

Paul, W9AC

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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Bruce]

You maybe confusing "Radiation Resistance" with "Feed point Resistance". 
It often will lower "Feed point Resistance", but raise "radiation 
Resistance". 73 Bruce


On 1/22/2019 9:45 AM, Peter Bertini wrote:

I would think adding radials would lower the Radiation resistance.  Also,
the SWR curve should narrow as ground losses are reduced;  since the effect
of ground loss resistance swamping the results lessens.

At some point I suggest, as others, that you get on for the contest and see
what you can do.  If you can run a bit of power, it will help.  Receiving
is indeed the tough nut to crack on 160 Meters.

Elevated radials may be worth a shot. I think Mike uses two with good
results. I went to a K2AV FCP and it works good enough for my needs. Even
with a K9AY loop system receiving is still my weak point.

Get on for the contests and have some fun.

Pete
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Peter Bertini]

I would think adding radials would lower the Radiation resistance.  Also,
the SWR curve should narrow as ground losses are reduced;  since the effect
of ground loss resistance swamping the results lessens.

At some point I suggest, as others, that you get on for the contest and see
what you can do.  If you can run a bit of power, it will help.  Receiving
is indeed the tough nut to crack on 160 Meters.

Elevated radials may be worth a shot. I think Mike uses two with good
results. I went to a K2AV FCP and it works good enough for my needs. Even
with a K9AY loop system receiving is still my weak point.

Get on for the contests and have some fun.

Pete
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Mike Waters]

Man, that seems awfully broad! Somewhere, you have losses, my friend.

You ARE measuring directly at the feedpoint, aren't you? And with the
antenna analyzer FLOATING (not touching you, the earth, or anything else)?

FWIW, the K9YC choke I used was about 6 turns of RG-6 wound through 4 or 5
*stacked* 2.4" Type 31 Fair-rite cores, *directly at the feedpoint*. Photos
linked to partway down the page at
http://www.w0btu.com/160_meters.html.

As you'll see, I'm an elevated radials man. Saves a lot of $ in radials
lying directly on the earth.

Also, please see
w0btu.com/Optimum_number_of_ground_radials_vs_radial_length.html

73, Mike
www.w0btu.com

On Mon, Jan 21, 2019, 7:46 PM Todd Goins  wrote:

> Hello,
>
> Per many people's recommendations I added 800ft of radials today. That is 8
> x 100ft each.  It made a difference on the analyzer which I'll summarize
> below. It was dark when I finished but here are a few data points. I think
> it is better. The wide SWR curve still bothers me but the resistance is
> coming up.
>
> This is also using the new K9YC cookbook choke with 18 turns of RG400
> around a 2.4" type 31 toroid.
>
> The values are Freq, SWR, R, X, Z
>
> 1810  1.43  42.0  -14.5  44.5
> 1820  1.31  43.2  -10.7  44.5
> 1830  1.21  44.1  -6.7   44.7
> 1840  1.13  45.0  -2.5   45.1
> 1850  1.10  45.9  1.7   45.9
> 1860  1.14  47.0  5.7  47.3
> 1870  1.23  48.0  10.1  49.1
> 1880  1.34  49.1  14.7  51.2
>
> Any thoughts?  The 160 CW contest is only 4 days away, I don't have a lot
> more time to make changes but I could run a "few" more radials...
>
> 73,
> Todd - NR7RR
>
>
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Jeff Blaine]

Todd, get on the contest and rock and roll.  I don't know of anyone on 
160m who has not given their antennas an iterative workout over time.  
Bet you will do just fine.  RX is the tougher nut anyway.  Good luck


73/jeff/ac0c
alpha-charlie-zero-charlie
www.ac0c.com

On 21-Jan-19 7:47 PM, Jamie WW3S wrote:
did you try transmitting with it, and see if any skimmers pick you up? 
just try sending test de urcall and check the RBN network, see how you 
are getting out


-Original Message- From: Todd Goins
Sent: Monday, January 21, 2019 8:45 PM
To: topband@contesting.com
Subject: Re: Topband: Inverted L improvements - Part 3 (now with data)

Hello,

Per many people's recommendations I added 800ft of radials today. That 
is 8

x 100ft each.  It made a difference on the analyzer which I'll summarize
below. It was dark when I finished but here are a few data points. I 
think

it is better. The wide SWR curve still bothers me but the resistance is
coming up.

This is also using the new K9YC cookbook choke with 18 turns of RG400
around a 2.4" type 31 toroid.

The values are Freq, SWR, R, X, Z

1810  1.43  42.0  -14.5  44.5
1820  1.31  43.2  -10.7  44.5
1830  1.21  44.1  -6.7   44.7
1840  1.13  45.0  -2.5   45.1
1850  1.10  45.9  1.7   45.9
1860  1.14  47.0  5.7  47.3
1870  1.23  48.0  10.1  49.1
1880  1.34  49.1  14.7  51.2

Any thoughts?  The 160 CW contest is only 4 days away, I don't have a lot
more time to make changes but I could run a "few" more radials...

73,
Todd - NR7RR
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Jamie WW3S]

did you try transmitting with it, and see if any skimmers pick you up? just 
try sending test de urcall and check the RBN network, see how you are 
getting out


-Original Message- 
From: Todd Goins

Sent: Monday, January 21, 2019 8:45 PM
To: topband@contesting.com
Subject: Re: Topband: Inverted L improvements - Part 3 (now with data)

Hello,

Per many people's recommendations I added 800ft of radials today. That is 8
x 100ft each.  It made a difference on the analyzer which I'll summarize
below. It was dark when I finished but here are a few data points. I think
it is better. The wide SWR curve still bothers me but the resistance is
coming up.

This is also using the new K9YC cookbook choke with 18 turns of RG400
around a 2.4" type 31 toroid.

The values are Freq, SWR, R, X, Z

1810  1.43  42.0  -14.5  44.5
1820  1.31  43.2  -10.7  44.5
1830  1.21  44.1  -6.7   44.7
1840  1.13  45.0  -2.5   45.1
1850  1.10  45.9  1.7   45.9
1860  1.14  47.0  5.7  47.3
1870  1.23  48.0  10.1  49.1
1880  1.34  49.1  14.7  51.2

Any thoughts?  The 160 CW contest is only 4 days away, I don't have a lot
more time to make changes but I could run a "few" more radials...

73,
Todd - NR7RR
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Todd Goins]

Hello,

Per many people's recommendations I added 800ft of radials today. That is 8
x 100ft each.  It made a difference on the analyzer which I'll summarize
below. It was dark when I finished but here are a few data points. I think
it is better. The wide SWR curve still bothers me but the resistance is
coming up.

This is also using the new K9YC cookbook choke with 18 turns of RG400
around a 2.4" type 31 toroid.

The values are Freq, SWR, R, X, Z

1810  1.43  42.0  -14.5  44.5
1820  1.31  43.2  -10.7  44.5
1830  1.21  44.1  -6.7   44.7
1840  1.13  45.0  -2.5   45.1
1850  1.10  45.9  1.7   45.9
1860  1.14  47.0  5.7  47.3
1870  1.23  48.0  10.1  49.1
1880  1.34  49.1  14.7  51.2

Any thoughts?  The 160 CW contest is only 4 days away, I don't have a lot
more time to make changes but I could run a "few" more radials...

73,
Todd - NR7RR
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Frank Krozel]

Fred had to laugh.
I fear my son (yeah a ham) will put all my stuff on the lawn with a small 
bucket for any money they feel it is worth.
Use iT!
de KG9H


> On Jan 21, 2019, at 8:44 AM,   wrote:
> 
> Thank You Guy for taking the time for all great the info.
> 
> I have several pieces of RG400 none are long enough.
> I was an airfield electrician for CVG airport.
> Got some out of planes and some from the FAA I would demo stuff for them.
> 
> I will be looking for some RG400 on the web to make a few proper chokes
> 
> I guess I don't know as much abt chokes as I thought.
> I figured any old wire would do.
> I will reread K9YC papers on the subject.
> 
> ''You can put your lifetime stash of RG400 in your will, and leave it to a 
> younger local ham, who will appreciate it.  :>)) 
> 
> That made me chuckle..when I die my kids will throw all my stuff in the 
> trash...  ;0 :)
> 
> Love this reflector always learning here.
> 
> Thanks
> Fred KB4QZH
> 
> 
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Topband: Inverted L improvements - Part 3 (now with data)

[fmoeves]

Thank You Guy for taking the time for all great the info.

I have several pieces of RG400 none are long enough.
I was an airfield electrician for CVG airport.
Got some out of planes and some from the FAA I would demo stuff for them.

I will be looking for some RG400 on the web to make a few proper chokes

I guess I don't know as much abt chokes as I thought.
I figured any old wire would do.
I will reread K9YC papers on the subject.

''You can put your lifetime stash of RG400 in your will, and leave it to a 
younger local ham, who will appreciate it.  :>)) 

That made me chuckle..when I die my kids will throw all my stuff in the 
trash...  ;0 :)

Love this reflector always learning here.

Thanks
Fred KB4QZH


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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Guy Olinger K2AV]

Hi, Fred. You said:

"Guy K2AV I'm guessing you don't like rg58 because of the center conductor
moving outwards??"

Nope.  :>))   RG58 is not RG400. That's why I don't like RG58.

RG400 is what should be used for winding coax on toroids. RG400 is a
currently manufactured item. It is INTENDED to handle sharp bends as found
in aircraft wiring harnesses (and therefore also handle being wound on
toroids). The center conductor is silvered stranded copper, the dielectric
is PTFE (Teflon), the shield is TWO dense woven layers of silvered copper
braid, and the jacket is PTFE.

RG400 is rated to 7 kW.

RG400 is Mil Spec. MIL-C-17 27478. Which means that if your house blows up
from a gas explosion, the RG400 will still be there working when the fire
is put out.

Essentially it never ever goes bad or weird unless catastrophically
treated, like crushed with a hammer, nailed through, ends submerged in
battery acid, or used as a tow rope for something heavy. I have one piece
of RG400 that was inappropriately used to arrest the fall of and suspend a
linear amp in mid-air. The coax still works, but it looks funny, and it
wasn't 50 ohms any more. A Chinese finger trap on the dielectric.

The silvered copper conductors in the double shields and stranded copper
center conductor will not deteriorate from occasional moist air in the coax
and convert it to many small conductors with performance changes, because
silver oxide is conductive.

The dense silvered copper shield weave, with two layers of shield weave in
RG400, makes for extremely good shielding. A lot of RG58 is cr*p shielding,
sparse enough to see through, sparse to maximize profit.

The PTFE in the jacket and dielectric is a low loss material, will not
deteriorate from ultraviolet. PTFE will not gradually shrink or crack by
leaching its chemical components.

The jacket and dielectric will not melt and ruin a connector when you
solder it, or when you forget it's there and put 1500 watts on it.

PTFE is a highly robust and predictable material. The PVC jacket
formulation on RG58 could be just about anything.

People have discovered that jumpers and leftover pieces of RG400 can be
sold on eBay. So you can pick up a ten foot piece of RG400 for less than
retail. I like the pieces with a male BNC on one end. I hate doing BNC
connectors. Brand-new coils of 100' plus can occasionally be had for as
little as 1.80 USD per foot, and regularly for 2.30 USD per foot, on eBay.

For all intents and purposes, a toroid wound with RG400 is a permanent
device, lifetime depending on the toroid instead of the coax.

You should buy enough RG400 so RG400 is the small coax that's "laying
around" and still good as new to do a project with, even if you bought it
20 years ago.

You can put your lifetime stash of RG400 in your will, and leave it to a
younger local ham, who will appreciate it.  :>))

RG400 is also K9YC's choice in his new
http://audiosystemsgroup.com/2018Cookbook.pdf. Check out the monster common
mode blocking choke wound with 23 turns of RG400 over a 4" OD, 3" ID, inch
thick #31 ferrite toroid. THAT'S a choke. 17K ohms resistive on 160.

73, Guy K2AV

On Sun, Jan 20, 2019 at 12:36 PM  wrote:

> Hello everyone.
>
> I also trying to improve things here on 160 and other bands.
> Going to make a few chokes.
> I have wound 8 turns thru 2.4 x2 31 mix but haven't seen any real
> improvement.
> Trying to get rid of some birdies.
>
> Guy K2AV I'm guessing you don't like rg58 because of the center conductor
> moving outwards??
>
> 73 Fred KB4QZH
>
>
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Topband: Inverted L improvements - Part 3 (now with data)

[fmoeves]

Hello everyone.

I also trying to improve things here on 160 and other bands.
Going to make a few chokes.
I have wound 8 turns thru 2.4 x2 31 mix but haven't seen any real improvement.
Trying to get rid of some birdies.

Guy K2AV I'm guessing you don't like rg58 because of the center conductor 
moving outwards??

73 Fred KB4QZH


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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Guy Olinger K2AV]

Hi Todd,

Have a look at the calculator at
https://chemandy.com/calculators/return-loss-and-mismatch-calculator.htm

This calculator allows me to compute the SWR for your data points, as if
the Z zero of the meter was 32 ohms. This is important because so many
excellent antennas exhibit raw feed R between 15 and 35 ohms. This exercise
will give me SWR numbers the same as if I had put a 32 ohm to 50 ohm unun
in front of your 50 ohm SWR meter. Using the calculator gives a revised and
normalized table:

1820  1.61  29.1  -14.3
1840  1.20  31.0  -5.7
1850  1.04  32.0  -1.3
1860  1.12  33.0   3.6
1880  1.49  35.3   13.0
1900  1.95  38  22.9

This allows me to determine matched to 50 ohm line 1.5:1 SWR points at 1825
and 1880 or a 1.5:1 bandwidth of 55 kHz. A good guess would be that the 2:1
bandwidth is nearly all of 1.8 to 1.9  Both are far too broad, indicating
considerable RF loss yet to be pin-pointed and remedied.

I have a full size inverted L over an FCP, whose feed R at the shack side
of the isolation transformer is 30 to 32 ohms. This conveniently allows me
to use a Balun Designs 16132 Unun (32 ohms in, 50 ohms out) to match the
natural R of the antenna to the 50 ohm feedline to the shack.

At the Unun output, my 1.5:1 points are 1807 and 1832 for a 1.5:1 SWR
bandwidth of 25 kHz.

On the shack side of 82 feet of LDF4-50A 1/2 inch hardline, the 1.5:1
points are 1804 and 1832 for a 1.5:1 SWR bandwidth of 28 kHz at the
operating position.

Over the last two years, this antenna has been carefully designed/worked
over to eliminate loss. Removing the loss will narrow SWR bandwidth.  My
shack SWR at 1880  is 4.8:1.  Switching in secondary matching (ATR30) is
necessary to work in the high 1.8's and above 1.9.

I would be interested in the RigExpert raw feed numbers without the choke
(I have a hard-to-shake dim view of RG58, especially old RG58). It would
also be helpful to have the RigExpert model number, and measurements taken
at 10 kHz points.

Good luck on the project. You have to keep working the problem.

73, Guy K2AV


On Fri, Jan 18, 2019 at 8:23 PM Todd Goins  wrote:

> Hello,
>
> I borrowed a RigExpert analyzer and was able to take measurements that
> folks were asking for without AM station overload. I also built the K9YC
> 160m choke (18 turns of RG58 on a type 31 2.4" toroid). That choke is at
> the feed point of the vertical. The analyzer was connected directly after
> the choke.
>
> I have a collection of data and typed it into Excel but I can summarize
> here.
>
> The values are Freq, SWR, R, X, Z
>
> 1810  2.1
> 1820  1.9  29.1  -14.3  32.4
> 1840  1.8  31.0  -5.7   31.5
> 1850  1.7  32.0  -1.3   32.1
> 1860  1.5  33.0  3.6   33.2
> 1880  1.6  35.3  13.0  37.6
> 1900  1.8  38.0  22.9  44.4
> 1920  2.1
> 1940  2.5
> 1960  3.0
> 1990  3.9
>
>  I still only have the 30 x 42' radials attached but can add about 5 x 100'
> more radials (in a non uniform layout) if that might help.
>
> Fair, bad, really bad, horrible, hopeless?  Any advice is appreciated.
>
> 73,
> Todd - NR7RR
> _
> Searchable Archives: http://www.contesting.com/_topband - Topband
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>
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Re: Topband: Inverted L improvements - Part 3 (now with data)

[Todd Goins]

Hello,

I borrowed a RigExpert analyzer and was able to take measurements that
folks were asking for without AM station overload. I also built the K9YC
160m choke (18 turns of RG58 on a type 31 2.4" toroid). That choke is at
the feed point of the vertical. The analyzer was connected directly after
the choke.

I have a collection of data and typed it into Excel but I can summarize
here.

The values are Freq, SWR, R, X, Z

1810  2.1
1820  1.9  29.1  -14.3  32.4
1840  1.8  31.0  -5.7   31.5
1850  1.7  32.0  -1.3   32.1
1860  1.5  33.0  3.6   33.2
1880  1.6  35.3  13.0  37.6
1900  1.8  38.0  22.9  44.4
1920  2.1
1940  2.5
1960  3.0
1990  3.9

 I still only have the 30 x 42' radials attached but can add about 5 x 100'
more radials (in a non uniform layout) if that might help.

Fair, bad, really bad, horrible, hopeless?  Any advice is appreciated.

73,
Todd - NR7RR
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Re: Topband: Inverted L improvements - Part 3

[Joe Subich, W4TV]

> I think theoretical is 32 ohms or so,

Theoretical impedance for a full height 1/4 wave vertical is 32 Ohms.
An inverted L (also "T" or other top loaded antenna) will be less
depending on the height of the vertical section and how much the
horizontal section slopes downward.


73,

   ... Joe, W4TV


On 2019-01-16 8:00 PM, Jamie WW3S wrote:


I read recently, maybe on this forum, that 32 ft radials were "long enough" if thats all 
you could get.I thought they needed to be longer as well, mine for my inv L are 132 ft long, 
but "bent" to keep them in my lot size.when we were talking about the feedpoint 
impedance of my L, thats when someone suggested that more radials 32 ft long, would be better than 
fewer radials that were longer

Mike, get rid of the 15' cable, try to measure the impedance with as short a 
piece of coax as possible, as close to the feedpoint as possible.thats what 
got me recently...ideal impedance will be mid to upper 30 ohmsI think 
theoretical is 32 ohms or so, add a few ohms for the ground.the more 
radials you add, the lower it will get


- Original Message -
From: "Mike Smith VE9AA" 
To: topband@contesting.com
Sent: Wednesday, January 16, 2019 7:32:09 PM
Subject: Re: Topband: Inverted L improvements - Part 3

Hi Todd and thanks for answering so quickly.

  


I am no expert. (I'm an Electronics Engineering Technologist and a ham for
40+ yrs,fwiw)

I won't debate the exact numbers on that table by K3LC referenced by K9YC,
(they are experts) but I will tell

you that it makes me go "hmmm" (as in a mild doubting tone)

  


A 42' radial on 160m is only something like 1/12th of a wavelength long.
(pretty short)

AM Broadcasters talk about the point of diminishing returns for on-ground
radials being

around 120 (or is it 240?) for full sized 1/4wl radials.  That would be the
equivalent of ~15,240feet on 160m.

You've laid out aprox 1260feet of wire (give or take).so aprox 1/12th or
.08% of optimum.

  


It's just not a lot of wire for a 160m antenna.  I have 2x 160m antennas
here.  One with about 7500' of wire on/in the ground and another with 2
raised radials (tuned, raised, 1/4wl each) and I can tell you the one with
7500' of wire under it always works better in true A/B comparisons. Not by a
lot, but it's noticeable.

  


I can't imagine you're anywhere' s near optimum.

  


I know "tone" doesn't come across in emails and postings, so I am not saying
this all in a sarcastic or snarky tone.  Just as a "matter of fact" type
tone.

  


With what you've described, it's probably as good as you'll get if you have
a typical small city lot and average soil.  You could play around with
chicken wire, tying your pool and well casing, fence, metal garden shed and
neighbours dog-run ,in to give you just as much conductive material under
the antenna as humanly possible or you can accept the limitations of a small
lot.

  


Personally, I don't give up easy..if it were me, I'd buy another couple
thousand feet of wire and put it down.

  


Something is just not right.

  


I'll let the *REAL* experts chime in, but my experience (such as it is),
tells me you're warming the ground or there's something else going on we
aren't yet aware of. (ginormous metal bldg. next door, hi).

  


GL with it Todd.  I hope there is an epiphany~!

  


truly.

  


Mike VE9AA

  


   Hi Mike,

  


Yes, it is a space issue. The presentation I was referring to is

http://audiosystemsgroup.com/160MPacificon.pdf where it has a table the

references a paper by K3LC that has "Optimum Use of Wire On/In Ground Over

Average Soil" and it lists 12 radials at 42' each to essentially use a 500'

spool of wire. I had more wire than that but not much more room. I could

run out a few wires in few directions to about 100' if that might help.  I

did use the antenna for a couple of evenings with only 12 radials and

yesterday I tacked on the additional 18.

  


That is why that decision was made.

  


I didn't think that SWR curve was good at all. But another guy just emailed

me and said that the BCB filter is probably messing up those readings and

they aren't accurate.  I can take SWR readings from my radio (in the shack)

with the filter not in line. Maybe that will show different values but it

will be attached to a 150' long piece of coax after the choke.

  


73,

Todd - NR7RR

  

  

  


Mike, Coreen & Corey

Keswick Ridge, NB

  


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Re: Topband: Inverted L improvements - Part 3

[Jamie WW3S]

I read recently, maybe on this forum, that 32 ft radials were "long enough" if 
thats all you could get.I thought they needed to be longer as well, mine 
for my inv L are 132 ft long, but "bent" to keep them in my lot size.when 
we were talking about the feedpoint impedance of my L, thats when someone 
suggested that more radials 32 ft long, would be better than fewer radials that 
were longer

Mike, get rid of the 15' cable, try to measure the impedance with as short a 
piece of coax as possible, as close to the feedpoint as possible.thats what 
got me recently...ideal impedance will be mid to upper 30 ohmsI think 
theoretical is 32 ohms or so, add a few ohms for the ground.the more 
radials you add, the lower it will get


- Original Message -
From: "Mike Smith VE9AA" 
To: topband@contesting.com
Sent: Wednesday, January 16, 2019 7:32:09 PM
Subject: Re: Topband: Inverted L improvements - Part 3

Hi Todd and thanks for answering so quickly.

 

I am no expert. (I'm an Electronics Engineering Technologist and a ham for
40+ yrs,fwiw)

I won't debate the exact numbers on that table by K3LC referenced by K9YC,
(they are experts) but I will tell

you that it makes me go "hmmm" (as in a mild doubting tone)

 

A 42' radial on 160m is only something like 1/12th of a wavelength long.
(pretty short)

AM Broadcasters talk about the point of diminishing returns for on-ground
radials being

around 120 (or is it 240?) for full sized 1/4wl radials.  That would be the
equivalent of ~15,240feet on 160m.

You've laid out aprox 1260feet of wire (give or take).so aprox 1/12th or
.08% of optimum.

 

It's just not a lot of wire for a 160m antenna.  I have 2x 160m antennas
here.  One with about 7500' of wire on/in the ground and another with 2
raised radials (tuned, raised, 1/4wl each) and I can tell you the one with
7500' of wire under it always works better in true A/B comparisons. Not by a
lot, but it's noticeable. 

 

I can't imagine you're anywhere' s near optimum.

 

I know "tone" doesn't come across in emails and postings, so I am not saying
this all in a sarcastic or snarky tone.  Just as a "matter of fact" type
tone.

 

With what you've described, it's probably as good as you'll get if you have
a typical small city lot and average soil.  You could play around with
chicken wire, tying your pool and well casing, fence, metal garden shed and
neighbours dog-run ,in to give you just as much conductive material under
the antenna as humanly possible or you can accept the limitations of a small
lot.

 

Personally, I don't give up easy..if it were me, I'd buy another couple
thousand feet of wire and put it down.

 

Something is just not right.

 

I'll let the *REAL* experts chime in, but my experience (such as it is),
tells me you're warming the ground or there's something else going on we
aren't yet aware of. (ginormous metal bldg. next door, hi).

 

GL with it Todd.  I hope there is an epiphany~!

 

truly.

 

Mike VE9AA

 

  Hi Mike,

 

Yes, it is a space issue. The presentation I was referring to is

http://audiosystemsgroup.com/160MPacificon.pdf where it has a table the

references a paper by K3LC that has "Optimum Use of Wire On/In Ground Over

Average Soil" and it lists 12 radials at 42' each to essentially use a 500'

spool of wire. I had more wire than that but not much more room. I could

run out a few wires in few directions to about 100' if that might help.  I

did use the antenna for a couple of evenings with only 12 radials and

yesterday I tacked on the additional 18.

 

That is why that decision was made.

 

I didn't think that SWR curve was good at all. But another guy just emailed

me and said that the BCB filter is probably messing up those readings and

they aren't accurate.  I can take SWR readings from my radio (in the shack)

with the filter not in line. Maybe that will show different values but it

will be attached to a 150' long piece of coax after the choke.

 

73,

Todd - NR7RR

 

 

 

Mike, Coreen & Corey

Keswick Ridge, NB

 

_
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_
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Re: Topband: Inverted L improvements - Part 3

[Mike Smith VE9AA]

Hi Todd and thanks for answering so quickly.

 

I am no expert. (I'm an Electronics Engineering Technologist and a ham for
40+ yrs,fwiw)

I won't debate the exact numbers on that table by K3LC referenced by K9YC,
(they are experts) but I will tell

you that it makes me go "hmmm" (as in a mild doubting tone)

 

A 42' radial on 160m is only something like 1/12th of a wavelength long.
(pretty short)

AM Broadcasters talk about the point of diminishing returns for on-ground
radials being

around 120 (or is it 240?) for full sized 1/4wl radials.  That would be the
equivalent of ~15,240feet on 160m.

You've laid out aprox 1260feet of wire (give or take).so aprox 1/12th or
.08% of optimum.

 

It's just not a lot of wire for a 160m antenna.  I have 2x 160m antennas
here.  One with about 7500' of wire on/in the ground and another with 2
raised radials (tuned, raised, 1/4wl each) and I can tell you the one with
7500' of wire under it always works better in true A/B comparisons. Not by a
lot, but it's noticeable. 

 

I can't imagine you're anywhere' s near optimum.

 

I know "tone" doesn't come across in emails and postings, so I am not saying
this all in a sarcastic or snarky tone.  Just as a "matter of fact" type
tone.

 

With what you've described, it's probably as good as you'll get if you have
a typical small city lot and average soil.  You could play around with
chicken wire, tying your pool and well casing, fence, metal garden shed and
neighbours dog-run ,in to give you just as much conductive material under
the antenna as humanly possible or you can accept the limitations of a small
lot.

 

Personally, I don't give up easy..if it were me, I'd buy another couple
thousand feet of wire and put it down.

 

Something is just not right.

 

I'll let the *REAL* experts chime in, but my experience (such as it is),
tells me you're warming the ground or there's something else going on we
aren't yet aware of. (ginormous metal bldg. next door, hi).

 

GL with it Todd.  I hope there is an epiphany~!

 

truly.

 

Mike VE9AA

 

  Hi Mike,

 

Yes, it is a space issue. The presentation I was referring to is

http://audiosystemsgroup.com/160MPacificon.pdf where it has a table the

references a paper by K3LC that has "Optimum Use of Wire On/In Ground Over

Average Soil" and it lists 12 radials at 42' each to essentially use a 500'

spool of wire. I had more wire than that but not much more room. I could

run out a few wires in few directions to about 100' if that might help.  I

did use the antenna for a couple of evenings with only 12 radials and

yesterday I tacked on the additional 18.

 

That is why that decision was made.

 

I didn't think that SWR curve was good at all. But another guy just emailed

me and said that the BCB filter is probably messing up those readings and

they aren't accurate.  I can take SWR readings from my radio (in the shack)

with the filter not in line. Maybe that will show different values but it

will be attached to a 150' long piece of coax after the choke.

 

73,

Todd - NR7RR

 

 

 

Mike, Coreen & Corey

Keswick Ridge, NB

 

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Inverted L improvements - Part 3

[Todd Goins]

Hi Mike,

Yes, it is a space issue. The presentation I was referring to is
http://audiosystemsgroup.com/160MPacificon.pdf where it has a table the
references a paper by K3LC that has "Optimum Use of Wire On/In Ground Over
Average Soil" and it lists 12 radials at 42' each to essentially use a 500'
spool of wire. I had more wire than that but not much more room. I could
run out a few wires in few directions to about 100' if that might help.  I
did use the antenna for a couple of evenings with only 12 radials and
yesterday I tacked on the additional 18.

That is why that decision was made.

I didn't think that SWR curve was good at all. But another guy just emailed
me and said that the BCB filter is probably messing up those readings and
they aren't accurate.  I can take SWR readings from my radio (in the shack)
with the filter not in line. Maybe that will show different values but it
will be attached to a 150' long piece of coax after the choke.

73,
Todd - NR7RR
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Inverted L improvements - Part 3

[Mike Smith VE9AA]

".have attached 30 insulated wire radials each 42' in length (as suggested

in a K9YC presentation referencing a K3LC study in the NCJ) laying on the

ground roughly evenly distributed. The paper said that 12 radials would be

"adequate" but I had room and materials for 30 so that's what I laid out.."

 

".I measured the SWR curve and it starts at 2.0 @ 1800 and bottoms around

1.4 @ 1840 but it doesn't rise above 2.0 again until 1940.  That is far too

broad, right?  Lots of loss somewhere still?..."

 

 

I believe it's way, wy too broad of an SWR Todd.  I think all your
power is going to warm worms (or whatever lives in the ground where you are
this time of year).

 

I'm curious.  Why did you use only 42' long radials?  If it's space
limitations, I understand.  Not all of us live in the country.  My $$ is on
a poor ground system. The "vertical" part sounds good.

 

GL with this.I've been following along.

 

Mike VE9AA

 

 

Mike, Coreen & Corey

Keswick Ridge, NB

 

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: Inverted L improvements - Part 3

[Todd Goins]

Thanks to everyone that has written to me on the reflector and via email.
I've read everything you've written and hopefully your efforts have helped
me or guided me towards getting this antenna working better.

I've made some changes, bought some equipment/parts and built some stuff
per all of your advise. So I have some new observations and data and a few
more questions.  I'd really just like to get this playing better for the
160m CW contest in a couple of weeks.

First, so I could use my antenna analyzer (by knocking down the 27.5KW AM
station just down the road) I bought a DLW Associates BCB brickwall filter
customized to have a strong dip at 1210kHz. It works great all across the
BC band and my transciever is happier and I can use it out at the antenna
to help the Comet CAA-500 analyzer actually make measurements.

I also ordered the 2.4" #31 toroids and some RG400 as suggested at the
often referenced K9YC website. I will build the choke as directed but for
now I am using a DX Engineering Maxi-Core feedline choke that is supposedy
effective to 160m but they provide no data sheet. I'll get the parts for
the K9YC designed choke this week and will substitute that right away.

The antenna (freshly measured and rehung) has a near-ground mounted feed
point. The insulated 14g THHN wire is a total of 135' in length. It goes
straight vertical for 90', makes a 90 degree bend and runs horizontally for
45'. It is well insulated at the end and it does not touch any trees at any
point.

I have attached 30 insulated wire radials each 42' in length (as suggested
in a K9YC presentation referencing a K3LC study in the NCJ) laying on the
ground roughly evenly distributed. The paper said that 12 radials would be
"adequate" but I had room and materials for 30 so that's what I laid out.

Here are some measurements I made and I can take others you may wish to
see. My analyzer does not sign the reactance value.

R=50 X=27 SWR=1.7 @ 1813 MHz
then also
R=50 and X=21 SWR=1.5 @ 1890 MHz

The lowest X value I could obtain is X=5 with R=35 SWR=1.4 @ 1845 MHz

This is with a 15' piece of coax from the feedpoint to the choke then a
very short jumper to the BCB filter then a short jumper to the analyzer.
I'll be able to put the choke right at the feedpoint (if that will make a
difference) when the toroid/RG400 arrives.

I measured the SWR curve and it starts at 2.0 @ 1800 and bottoms around
1.4 @ 1840 but it doesn't rise above 2.0 again until 1940.  That is far too
broad, right?  Lots of loss somewhere still?

So, that's where I am. It has worked US coast to coast, easily to Alaska
and Hawaii and to N. Cook. It is being heard in VK and I worked half a
dozen JAs all with 100 watts but I still think it has many problems. This
is definitely an improvement thanks to all of your tips and advise but what
can I reasonably do to make it better or am I at diminishing returns?

I'm willing to put some more time and energy into it and also take more
measurements if that would help. Any ideas?

73,
Todd - NR7RR
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Inverted L improvement question

[Guy Olinger K2AV]

Given caveats stated below, the short answer is I'd bet with odds it
wouldn't make much difference.

Long answer:

One of the benefits of an end-fed half-wave L on 80 meters is the hi Z
feed, tolerating ghastly ground systems, and having all the current up high
at the bend. Arguably, this makes the 80EFHWL the best single wire 80m
antenna for a mix of DX and local (therefore also contesting) operation.
The huge drawback for most is the need for an out-in-in-the-weather tuning
device as you cannot feed it directly with a run of coax. It also is fairly
narrow band, except for CW only operators. Those who need the entire band
need to so something not-simple at the ground feed to cover a significant
range of the 75-80m band.

The half square is two of those end to end, coming together in the middle
of the 1/2 wave horizontal. On 160 that's 539 feet of wire up in the air.
If you got the space and support for that and you want that broadside
direction, that's going to be a killer antenna.

Many of the half-square illustrations show a low Z feed at one of the upper
corners. That would avoid some of the issues at ground with high Z feed.
BUT the feedline would need to be broken up at the feed and halfway going
down, and at the bottom with VERY robust common mode current blocks. See
some of K9YC's new RG400 on #31 ferrite choke designs with 15K+ ohms of
blocking for something that would actually do the job with very minimal
power loss.

The other answer, as you have implemented to to deal with the high
impedance feed at one of the ends. This requires that at the end the
antenna looks like an electrical full wave wire.

Equal coils at the corners have sometimes allowed smaller physical
dimensions. But as soon as you start modifying the antenna, then questions
emerge which need modeling to answer. So there is no certain
one-size-fits-all answer to your question without model analysis of the
not-quite-half-square you have in the air. Versions with modified
dimensions have to be carefully designed to avoid dropping back into ground
involvement and possible related losses.

Given your 2000 ohm end to ground feed Z of the "modified" version you have
up, you have PROBABLY managed to avoid issues that would kill its ground
independence.

To answer the question far more completely, model it along with any
antennas and conductors within a 500 foot radius, INCLUDING TOWERS AND
FEEDLINES.

The half square is a great idea that can be screwed up with less than full
implementation, or like many other excellent designs, can be totally
screwed to the wall by unconsidered nearby conductors.

73, Guy K2AV.

On Tue, Jan 8, 2019 at 3:45 PM Dick Bingham  wrote:

> Hello Guy (and the group)
>
> I just finished reading your reply/observations on 160-Meter verticals -
> L's, etc - and wonder what your thoughts may be for the so-called
> "Half-Square" antenna (H-S) where the high current point is at the top of
> the array and the antenna is high-voltage-fed at the bottom.
>
> I have a terrible QTH situation where ground conditions are very poor -
> basically river deposited gravel
> and sand sub-soaked by glacier and snow-melt water covered by several feet
> of organic matter. It is an electrically quiet area - S-0 or so - with
> noise basically all propagated non-man made noise.
>
> The H-S antenna I use (actually a sloping H-S with top phasing wire at
> ~90-feet) has 5ea 136-foot radials and performs very well in contests using
> 100-watts or less.
>
> My question is, given the low current at-ground feed point with Zo ~
> 2000-ohms or so, what sort of improvement might one expect if the radial
> field was significantly improved?
>
> 73 to all -  Dick/w7wkr at CN98pi
> =
> Message: 1
> Date: Mon, 7 Jan 2019 12:07:16 -0500
> From: Guy Olinger K2AV 
> To: Todd Goins 
> Cc: TopBand List 
> Subject: Re: Topband: Inverted L improvement question
> Message-ID:
>
> Content-Type: text/plain; charset="UTF-8"
>
> Apologies to all for delay in response.
>
> Losses related to ground and close dielectric materials remain the
> single monster gorilla in the room for improving TX performance of
> vertical antennas
> BIG SNIP
>
>
_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Topband: Inverted L improvement question

[Dick Bingham]

Hello Guy (and the group)

I just finished reading your reply/observations on 160-Meter verticals - L's, 
etc - and wonder what your thoughts may be for the so-called "Half-Square" 
antenna (H-S) where the high current point is at the top of the array and the 
antenna is high-voltage-fed at the bottom.

I have a terrible QTH situation where ground conditions are very poor - 
basically river deposited gravel 
and sand sub-soaked by glacier and snow-melt water covered by several feet of 
organic matter. It is an electrically quiet area - S-0 or so - with noise 
basically all propagated non-man made noise.

The H-S antenna I use (actually a sloping H-S with top phasing wire at 
~90-feet) has 5ea 136-foot radials and performs very well in contests using 
100-watts or less. 

My question is, given the low current at-ground feed point with Zo ~ 2000-ohms 
or so, what sort of improvement might one expect if the radial field was 
significantly improved?

73 to all -  Dick/w7wkr at CN98pi
=
Message: 1
Date: Mon, 7 Jan 2019 12:07:16 -0500
From: Guy Olinger K2AV 
To: Todd Goins 
Cc: TopBand List 
Subject: Re: Topband: Inverted L improvement question
Message-ID:
   
Content-Type: text/plain; charset="UTF-8"

Apologies to all for delay in response.

Losses related to ground and close dielectric materials remain the
single monster gorilla in the room for improving TX performance of
vertical antennas
BIG SNIP

_
Searchable Archives: http://www.contesting.com/_topband - Topband Reflector

Re: Topband: Inverted L improvement question - Part 2

[Wes Stewart]

I could give other advice but the best that I could offer is to check out 
Rudy's, N6LF, site: https://www.antennasbyn6lf.com/  Regrettably, this isn't all 
that he's published so further searching might be in order.  QEX published a 
series in 2009-2010 of his stuff.


In my "Antennas" document folder on my hard drive I have a "Severns" subfolder 
with practically everything he's written saved.  This is a gold mine, only the 
gold is free.


In particular for your needs see LF-MF antenna notes.

Wes  N7WS

On 12/28/2018 4:35 PM, Todd Goins wrote:

Thanks for reading and any advise you can give.
73,
Todd - NR7RR


_
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Re: Topband: Inverted L improvement question

[Guy Olinger K2AV]

Hi, Grant.

Your original was posted to the reflector as well, and I'll let this
go there as well.

3:1 current imbalance, whether scalar or not, is grotesquely large
with 8 evenly spaced elevated equal length radials. I presume you have
already looked for connection issues at the center of the radials and
insulator issues out at the ends of the radials, and have walked the
radials looking for vegetation hanging on the radials. You would have
fixed that and moved on.

I think Kirchoff is overkill for the problem. I'm not sure he applies
at all with radials coupled inductively and capacitively to "infinite"
planetary size current sinks like ground viewed as a geographical
conductor. I think a lot of RF earth current (hence also radial
behavior) is better understood by the way charge moves around in a
lightning strike than by a circular radio circuit. The math is
dreadful for a radial analyzed as a single ended circuit, but that's
our problem, not nature's. We have a history of wanting to promote our
modeling programs to "natural" law, and somewhere in our unconscious
resist any addition of other factors to our calculations which can
create square law increases in problem and solution complexity.

Some practical things: Radial field screw-ups generally have almost no
effect on pattern at all. I modeled your antenna finally increasing to
200 ohm (!!!) loads inserted almost at the center into all the radials
on one side. This is a very large distortion of radial function, the
degree of unbalance required to produce three times the current in the
unloaded radials as loaded. This whale-sized distortion only makes the
azimuth pattern favor the unloaded side by about a dB. A counterpoise
hopefully will return 99% of the current forced into it, with minimal
energy sent to the far fields to distort the pattern of the aerial
wires. RF gone to counterpoise losses will not largely change pattern
any more than a parallel feed of antenna and dummy load will change
the antenna pattern.

So while the discovery of current imbalance in the radials may be
unnerving, it could be a result instead of a cause. And it does not
seem to reach the level of why you're getting thrashed in the
pile-ups.

What's more likely going on is akin to work done at N1LN where THREE
towers needed to be detuned to get clean pattern all around from his
two phased verticals. At the time only one vacuum variable was
available for the detuning. The closest tower was detuned with that.
The next closest tower was adjusted with that variable cap, measured
for value, and then returned to the first tower and reset. Using caps
rated for 100 watt transmitters, if that, the measured value was
constructed with a combination of fixed caps and put in place.

Detuning the towers made massive changes in the verticals' tuning.

A 160 contest was coming up in a few days and no chance to get a
variable in place. (Isn't it always? Do any of us ever do anything
sufficiently in advance?) As the story goes, a multi-op effort,
sometime 10 or 11 pm Friday night, one of the operators stepped out
the back door to smoke a cigarette, and noticed a strong acrid burning
smell. Not seeing a fire he ran in to get Bruce to find out what was
burning. Long story to short, the 1500 watts on the phased verticals
put enough current on the tower detuning to totally
smoke/roast/charcoal the detuning cap made up from fixed caps and
stink up the entire back acreage with the smoke therefrom.

The Acom 2000A had auto-tuned around the changing Z to the verticals
as the caps burned up, leaving the smokey back acreage as the only
tangible evidence of what was going on.

Without specific work to prevent it, RF current induced in a tower
will be driven into the dirt at the tower base, via the tower members
themselves, and via capacitive/inductive coupling of dirt from control
cables and coax shields. The circuit equivalent is a parallel feedline
to a big transformer (verticals inducing the tower) connected to a
huge big resistor made of dirt.

Since you have NEC 4.2, no excuse for not doing a whole property model
of all conductive materials and seeing where the current is flowing.
You can validate this by doing current measurements on every conductor
you can reach.

I did a whole property model for Bruce and it clearly showed a
completely unexpected high current on all the towers and conductors at
the base. It immediately pin-pointed the need for multiple detunings.
It also predicted severe far field pattern distortion that was
verified by measurements on a Potomac Instruments FIM-41 commercial
field strength meter at distances 2-5 miles in various directions.

A tower only 250 feet from a 160 vertical should be considered a
close-coupled transformer "winding".

Getting back to where you are

Can you supply the current reading and compass orientation of each of
the radials? There may be something suggested by that data. Also can
you run the following and report those results. (I'm including