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In the write-up, the last 'subject' was professionally done. Notice it
consists of 16 turns of AWG #14 solid copper wire wound in a bifilar
manner. This one measured the best and is the size of the cores you have.
So,........ try to duplicate that choke. Again, the last one shown in the
write-up attached to the last 'reply'.

Dave - W?LEV

On Thu, Nov 5, 2020 at 11:51 PM David Eckhardt via groups.io <davearea51a=
[email protected]> wrote:

Attached are the measured data sets for the CM chokes I illustrated in the
previous email plus a couple of others

Dave - W?LEV

On Thu, Nov 5, 2020 at 11:40 PM David Eckhardt <davearea51a@...>
wrote:

For the doublet which consists of two roughly equal lengths of wire each
side of the center insulator, just wind yourself a common mode choke. It
will serve very well as a balun as it will discourage common mode

currents,

and, therefore, current on the outside of the coaxial feedline (the
function of a balun). I use AWG #14 Davis RF superflex wire (finely
stranded and coated) , but I have 3" OD cores. With your smaller core,
smaller wire would be advised. You'd do far better to use #18 or #20
stranded (it forms easier) and coated wire for your size cores. Wind in

a

bifilar manner, two parallel conductors through the red core. Do not

twist

the wires. Without overlapping bifilar windings, try to get 12 to 15

turns

of wire on your core. It choke is bipolar, so one side of the pair
connects to the coax while the other side of the pair connects at the
center insulator to your two wires. That will work well to isolate

current

on the outside of the coaxial cable from becoming part of the antenna and
is good for 100 to 150-watts. It will not function much as an impedance
transformer, which you do not want using an antenna matching network,
a.k.a., an antenna 'tuner'. I'll attach a picture of two of my common
mode chokes wound on two stacked 3" cores (to assure adequate magnetic
current capability within the magnetics at legal limit). I have
measurements of these chokes made with the HP 8753C VNA somewhere on the
hard drive.

[image: image.png]

The SO-239 connects to the coaxial cable. The banana plugs connect to my
open wire feeders. Left choke is wound with #12 insulated stranded house
wire (PVC coating) while the right-hand choke is wound with the DavisRF
superflex stranded insulated #14 wire.

Dave - W?LEV


On Thu, Nov 5, 2020 at 11:06 PM <deadman1966@...> wrote:

Thanks for the detailed explanation of the graphs I could certainly
follow it on the graphs.

I have 2 of the T130-2 cores but the only mag wire i have measures
1.90mm across
which is way too heavy to get 18 turns of 3 wires.

I do have a ton of coated 14awg gauge stranded wire or 14/2 electrical
wire as well.

Can either of those be used in a balun at 100-150 watts?

Since the gypsy balun is trash and its sealed in a way the is not open
able i would
like to get a balun wired on the core and perhaps at least use the
connectors from
the trashed one, lol after likely having to saw it in half in the

middle.

I got two cores i also want to make a 9:1 for playing with end feed

wires

as well.

--
*Dave - W?LEV*
*Just Let Darwin Work*

--
*Dave - W?LEV*
*Just Let Darwin Work*

--
*Dave - W?LEV*
*Just Let Darwin Work*

Attached are the measured data sets for the CM chokes I illustrated in the
previous email plus a couple of others

Dave - W?LEV

On Thu, Nov 5, 2020 at 11:40 PM David Eckhardt <davearea51a@...>
wrote:

For the doublet which consists of two roughly equal lengths of wire each
side of the center insulator, just wind yourself a common mode choke. It
will serve very well as a balun as it will discourage common mode currents,
and, therefore, current on the outside of the coaxial feedline (the
function of a balun). I use AWG #14 Davis RF superflex wire (finely
stranded and coated) , but I have 3" OD cores. With your smaller core,
smaller wire would be advised. You'd do far better to use #18 or #20
stranded (it forms easier) and coated wire for your size cores. Wind in a
bifilar manner, two parallel conductors through the red core. Do not twist
the wires. Without overlapping bifilar windings, try to get 12 to 15 turns
of wire on your core. It choke is bipolar, so one side of the pair
connects to the coax while the other side of the pair connects at the
center insulator to your two wires. That will work well to isolate current
on the outside of the coaxial cable from becoming part of the antenna and
is good for 100 to 150-watts. It will not function much as an impedance
transformer, which you do not want using an antenna matching network,
a.k.a., an antenna 'tuner'. I'll attach a picture of two of my common
mode chokes wound on two stacked 3" cores (to assure adequate magnetic
current capability within the magnetics at legal limit). I have
measurements of these chokes made with the HP 8753C VNA somewhere on the
hard drive.

[image: image.png]

The SO-239 connects to the coaxial cable. The banana plugs connect to my
open wire feeders. Left choke is wound with #12 insulated stranded house
wire (PVC coating) while the right-hand choke is wound with the DavisRF
superflex stranded insulated #14 wire.

Dave - W?LEV


On Thu, Nov 5, 2020 at 11:06 PM <deadman1966@...> wrote:

Thanks for the detailed explanation of the graphs I could certainly
follow it on the graphs.

I have 2 of the T130-2 cores but the only mag wire i have measures
1.90mm across
which is way too heavy to get 18 turns of 3 wires.

I do have a ton of coated 14awg gauge stranded wire or 14/2 electrical
wire as well.

Can either of those be used in a balun at 100-150 watts?

Since the gypsy balun is trash and its sealed in a way the is not open
able i would
like to get a balun wired on the core and perhaps at least use the
connectors from
the trashed one, lol after likely having to saw it in half in the middle.

I got two cores i also want to make a 9:1 for playing with end feed wires
as well.

--
*Dave - W?LEV*
*Just Let Darwin Work*

--
*Dave - W?LEV*
*Just Let Darwin Work*

For the doublet which consists of two roughly equal lengths of wire each
side of the center insulator, just wind yourself a common mode choke. It
will serve very well as a balun as it will discourage common mode currents,
and, therefore, current on the outside of the coaxial feedline (the
function of a balun). I use AWG #14 Davis RF superflex wire (finely
stranded and coated) , but I have 3" OD cores. With your smaller core,
smaller wire would be advised. You'd do far better to use #18 or #20
stranded (it forms easier) and coated wire for your size cores. Wind in a
bifilar manner, two parallel conductors through the red core. Do not twist
the wires. Without overlapping bifilar windings, try to get 12 to 15 turns
of wire on your core. It choke is bipolar, so one side of the pair
connects to the coax while the other side of the pair connects at the
center insulator to your two wires. That will work well to isolate current
on the outside of the coaxial cable from becoming part of the antenna and
is good for 100 to 150-watts. It will not function much as an impedance
transformer, which you do not want using an antenna matching network,
a.k.a., an antenna 'tuner'. I'll attach a picture of two of my common
mode chokes wound on two stacked 3" cores (to assure adequate magnetic
current capability within the magnetics at legal limit). I have
measurements of these chokes made with the HP 8753C VNA somewhere on the
hard drive.

[image: image.png]

The SO-239 connects to the coaxial cable. The banana plugs connect to my
open wire feeders. Left choke is wound with #12 insulated stranded house
wire (PVC coating) while the right-hand choke is wound with the DavisRF
superflex stranded insulated #14 wire.

Dave - W?LEV

--
*Dave - W?LEV*
*Just Let Darwin Work*

Thanks for the detailed explanation of the graphs I could certainly follow it on the graphs.

I have 2 of the T130-2 cores but the only mag wire i have measures 1.90mm across
which is way too heavy to get 18 turns of 3 wires.

I do have a ton of coated 14awg gauge stranded wire or 14/2 electrical wire as well.

Can either of those be used in a balun at 100-150 watts?

Since the gypsy balun is trash and its sealed in a way the is not open able i would
like to get a balun wired on the core and perhaps at least use the connectors from
the trashed one, lol after likely having to saw it in half in the middle.

I got two cores i also want to make a 9:1 for playing with end feed wires as well.

No.....NO.....N O.....!! Something is wrong, here. Look at just the
Smith Chart! Open shows lots of loss. Short shows very high Z. 50-ohm
termination shows high Z and totally inductive. All show extremely bad
return loss. Read from the Smith Chart markers (values given in the
numerical data to the left of the chart):
SWR Open: 30 MHz: 109:1 1.5 MHz: 1.9:1
SWR Short: 30 MHz: 196:1 1.5 MHz: 3.9:1
SWR Terminated: 30 MHz: 94:1 1.5 MHz: 62:1
I would conclude this balun is trash!!!!!! The previous commenter is not
familiar with what the return loss plot represents. Low numbers, which are
shown in these plots for all three configurations of the balun (open,
shourt, and properly terminated) are small which indicate much of the
source energy is reflected back to the input port. Large numbers of return
loss indicate low SWR while small numbers of return loss indicate high
SWR.

Again, based on the well executed measurements, that balun is trash.

Dave - W?LEV

--
*Dave - W?LEV*
*Just Let Darwin Work*

so if the balun is good how can the wires themselves be bad?

I would have expected this ant to be usable across the band windcamp advertised it to work at 5-50Mhz but it seems in most cases my Kenwood would likely not even auto tune it so i can transmit.

Can anyone suggest another ant that is worth buying I am tried of wasting money on this.

From the plot with 50 Ohm resistor you can see, that the balun is good (VSWR < 1.5) from 3 MHz to 30 MHz. The other plots are unimportant.

But remember that an antenna with bad VSWR will also give that bad VSWR through your balun to the transceiver.

73, Günter, DK5DN

Am 05.11.2020 um 21:10 schrieb deadman1966@...:

Thanks Larry, yes I thought to remember that and searched the forum using "H4 LCD screen" etc. but no luck. Will try again using his name for the search.

Best regards,

Jos

Op 5-11-2020 om 18:35 schreef Larry Rothman:

I decided to test the Balun itself maybe someone can help me read these plots.

I have one plot with the ant lead of balun open, shorted and with 2 100ohm resistors in parallel that read 49.9 ohms on my digital meter.

Hi Ernest,

No problem abt the name and thanks for the info.

Regards,

Jos

Op 5-11-2020 om 17:40 schreef ERNEST AEC-RADIO:

I sill have the copy of MININEC that I had to sign for from the Naval OceansResearch Lab 33 years ago.?? Don't do a lot of simulation.? I have an antenna rangethat goes up to 30 GHz.?? Currently have 6 antennas in orbit, and working on3 more at the moment.
The Nano's are very handy tools. ? I own three.? 250 lbs lighter than my 8510!
Have used NEC for 33 years but it cannot simulate the antennas I specialize in.
Printed Circuit Board Antennas| Commercial and Hobby Antennas

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Printed Circuit Board Antennas| Commercial and Hobby Antennas


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Kent

PS ELNEC and EZNEC?? Brings back memories.? Many years ago????? Roy and I both worked at Tek.

Yes, quite a number of antennas modeled and built using 4NEC2 by myself!!
And,..... I have the professional equipment to do proper testing including
an HP 8753C VNA with associated S-Parameter test set and the full line of
HP cal standards and several spectrum analyzers. You are quite mistaken in
your statements about 4NEC2. Dipoles, J-poles, Yagis, Helices,....... All
designed with 4NEC2, built, and properly tested using the above
equipment. Possibly you believe that 4NEC2 falls in what you state:

" Oh, you get nice fancy diagrams and plots, but no where near the
test results. There are holes in those programs!!! Kent
WA5VJB"

Possibly you have not spent the time learnimg how to properly utilize the
application?

I'll agree, 4NEC2 is not the easiest application to initially use. I
usually recommend potential users first 'cut their teeth' on EZNEC which
has far fewer hooks, nooks, and crannies, but it teaches the basics of
finally stepping up to 4NEC2. It is a highly capable application for
modeling and analyzing various antenna designs.

Dave - W?LEV

--
*Dave - W?LEV*
*Just Let Darwin Work*

Pretty models, but have any been tested?
So far we have two families of antennas that HFSS cannot model.
Oh, you get nice fancy diagrams and plots, but no where near thetest results.???? There are holes in those programs!!!?? Kent WA5VJB

4NEC2 can model a helix quite well. I've designed and constructed several
using that modeling application:



Dave - W?LEV

On Thu, Nov 5, 2020 at 4:51 PM Martin via groups.io <martin_ehrenfried=
[email protected]> wrote:

On Thu, Nov 5, 2020 at 12:35 PM, Dr. David Kirkby, Kirkby Microwave Ltd
wrote:

In short, it looks quite a poor design to me.

That could well be the case, when Sandpiper were manufacturing those
antennas back in the day, their test equipment was fairly limited.

I believe they are better equipped now.

--
Regards,

Martin - G8JNJ

--
*Dave - W?LEV*
*Just Let Darwin Work*

Thank you Dave,
Got Your point.
I removed the antenna from the roof and brought to the shack and measurements withouth the cable were really close to the real SWR as seen from TX.

Next step would be VNA calibration at the end of the coaxial cable - antenna site.
Not an easy task!

73 de I0MOM Marco

Inviato da iPad

Hugen had previously posted the part number in the forum. I think if you search his posts and "LCD" from Nov 2019 through to around Feb 2020, you'll find the post.

On Thu, Nov 5, 2020 at 12:35 PM, Dr. David Kirkby, Kirkby Microwave Ltd wrote:

In short, it looks quite a poor design to me.

That could well be the case, when Sandpiper were manufacturing those antennas back in the day, their test equipment was fairly limited.

I believe they are better equipped now.

--
Regards,

Martin - G8JNJ

Jos:
I apologize for not looking at your name...
I fat fingered my keyboard....again!

On Thu, Nov 5, 2020 at 9:25 AM ERNEST AEC-RADIO via groups.io <aecradio1=
[email protected]> wrote:

Joe:
Because the LCD is adhered to the board, you will need to pry it loose from
its adhesive bond. There is normally a numbering system imprinted on the
display, which denotes manufacturer name, model and possibly more data to
decode display type as well.
Sorry I can not be of more help.
Ernest
KA9UCE

On Thu, Nov 5, 2020 at 9:18 AM Jos Stevens <jrs@...> wrote:

Hi all,
I have to replace the LCD screen of my NanoVNA-H4, please what is the

type

number and/or where to buy ?
Thanks in advance,
Jos

Joe:
Because the LCD is adhered to the board, you will need to pry it loose from
its adhesive bond. There is normally a numbering system imprinted on the
display, which denotes manufacturer name, model and possibly more data to
decode display type as well.
Sorry I can not be of more help.
Ernest
KA9UCE

Hi all,
I have to replace the LCD screen of my NanoVNA-H4, please what is the type number and/or where to buy ?
Thanks in advance,
Jos