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On 1/27/21 4:58 PM, n2msqrp wrote:

Because of the temperatures involved in the fabrication process solder

would melt on plated stranded wire so teflon wire is either available
silver plated or bare copper wire.

It used to be available for a decent price at ham fests years ago. I

don't knoe know since the proce of all surplus wire has risen.

Mike N2MS

$650/for 100ft from Digikey - Alpha 5859/12 WH005 MIL-W-16878/4 Type E

$434/100ft for AT121925 WH005 (19/25 strand copper silver coated)


you could probably find a less expensive insulation that works as well,
but "dollars/ft" is what you're looking at.

I'll bet a lot of the cost is NOT the copper cost..

So running a 4 wire twist (2 in parallel) might actually be cheaper.
That would be AWG 15

AWG16 is about 129/100ft and TFE (not PTFE) insulation, still 600V,
still good to 200C.


and you can buy these things by the foot (even from Digikey).

On 01/27/2021 4:09 PM David Eckhardt <davearea51a@...> wrote:


I was also surprised it broke down, but every CMC I wound with solid #12
enameled wire broke down between 400 and 700 watts. I believe it has a

lot

I have not tried or thought of using teflon coated silvered conductor.

I

need to find it and, if not too expensive, give it a try.

I have found that using regular magnet wire with teflon tubing slid over
the wire will easily handle 2KW. I have wound a number of 4:1 transformers
as well as 49:1 transformers for EFHW using this method. All the balun
designs use a similar scheme; most likely due to the cost and difficulty in
obtaining silvered wire.

Ken WB6MMV

On Wed, Jan 27, 2021 at 2:10 PM David Eckhardt <davearea51a@...>
wrote:

I was also surprised it broke down, but every CMC I wound with solid #12
enameled wire broke down between 400 and 700 watts. I believe it has a

lot

to do with the impedances in which the CMCs are installed. My W/C is on
40-meters where I measure 1161 - j1110 at 7.0 MHz. My lowest impedance

is

at 2.0 MHz and measures 19 - j288.

I have not tried or thought of using teflon coated silvered conductor. I
need to find it and, if not too expensive, give it a try.

I rewound the 400-31 single core with the DavisRF 'antenna' wire with no
problems to at least 1.2 kW. It is certainly better at CM impedance than
the 43 material especially on 160 and 75 meters but 43 is a bit better on
the higher bands - as expected.

Out of all the CMCs I've wound and tested, I have three that I can use,

all

wound with the DavisRF #14 stranded and insulated antenna wire: 1)
240-31, 15 turns, 2) 300-43, 16 turns, and 3) 400-31, 21 turns.

Those

remaining do not perform well under DM loss (rejection) or phase balance
(π-radians out of phase) and/or amplitude balance on the DM side. I'm
going shopping for Teflon coated silvered solid conductor.

Dave - W?LEV

On Tue, Jan 26, 2021 at 11:26 PM Jim Lux <jim@...> wrote:

On 1/26/21 3:04 PM, n2msqrp wrote:

Dave,

Have you tried teflon covered silver plated wire?

Mike N2MS

The silver doesn't help much for RF conductivity, but it is a LOT

easier

to solder to.

I'm kind of surprised that magnet wire broke down. Most magnet wire is
good for a kilovolt or so, because motors and transformers get hi-pot
tested at 2-5kV.

Decent insulated magnet wire



Catalog here:


AWG 12 copper bare is 0.0808 (nom)

single build is 0.0825 (i.e. the insulation is 8.5 mils (0.2 mm) thick

heavy build is 0.0842 is twice as thick. (0.4mm)


most plastics have breakdown strength of 20 kV/mm or more, especially
for thin layers.

PTFE (Teflon) and Polyimide (Kapton) are a lot better (100 kV/mm)

Polyester (Mylar) is in between (50kV/mm)

Note that thinner layers have a higher breakdown voltage per mm (that
is, you might find that a layer that's 0.1 mm and 1mm have almost the
same breakdown voltage)

Formvar is about 11kV as typically applied to wire.

On 01/26/2021 3:30 PM David Eckhardt <davearea51a@...> wrote:


Those wound with the #12 enameled solid conductor do not take power

with

my ant/feedline impedances resulting in discharges between bifilar

pairs

(not between individual bifilar windings). Also, the green wire of
unknown insulation does not take power. So, those CMCs wound with

solid

conductor are coming apart and being rewound in some fashion or

another

with the DavisRF "antenna" wire which seems to take power to at

least

1.2

kW. Your mileage may vary with different impedances presented to

the

chokes.

Those frequencies on which I tried the CMCs at power are:
3.8 MHz 24 - j56
7.15 MHz 493 - j740
Impedances noted are measured at the shack end of the parallel wire
feedline.

Dave

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

Got my nifty NanoVNA yesterday. The unit works but it will not charge the battery nor will it be recognized by my Win PC. I suspect the USB cable is bad, but it could be the connector on the board. Anyone else experience this or have a “fix”. I don’t recognize the type of connector on the unit.

On 01/27/2021 4:09 PM David Eckhardt <davearea51a@...> wrote:


I was also surprised it broke down, but every CMC I wound with solid #12
enameled wire broke down between 400 and 700 watts. I believe it has a lot

I have not tried or thought of using teflon coated silvered conductor. I
need to find it and, if not too expensive, give it a try.

I finally started learning about this thing and all the videos I've seen
so far show four traces. I've only got two. Do I need a firmware update,
or what?

Ik cant open the file:-(

73 Arnold pe1owg

Paul, It's a pdf file - you can print your own individual pages using
Adobe Reader

On Wednesday, January 27, 2021, 1:37:17 p.m. EST, Paul W8SBH <
proinwv@...> wrote:

I really appreciate what you are doing. I have printed v1.5 and now I
wonder if there is a possibility of just printing certain pages of v1.6 to
replace same.

At the same time I don't want to be asking an unreasonable request.

Paul W8SBH

On Tue, Jan 26, 2021, 3:10 PM [email protected] Notification <
[email protected]> wrote:

The following files have been uploaded to the Files area of the
[email protected] group.

- /Absolute Beginner Guide to The
NanoVNA/Absolute_Beginner_Guide_NanoVNA_v1_6.pdf
<

/g/nanovna-users/files/Absolute%20Beginner%20Guide%20to%20The%20NanoVNA/Absolute_Beginner_Guide_NanoVNA_v1_6.pdf

*By:* Martin J.K.

*Description:*
New in version 1.6: - expanded firmware upgrade and the driver
installation section - some typo errors corrected. Thanks to everyone who
points me to typos and email good suggestions for improvement.

On 1/26/21 3:04 PM, n2msqrp wrote:

Dave,

Have you tried teflon covered silver plated wire?

Mike N2MS

The silver doesn't help much for RF conductivity, but it is a LOT easier
to solder to.

I'm kind of surprised that magnet wire broke down. Most magnet wire is
good for a kilovolt or so, because motors and transformers get hi-pot
tested at 2-5kV.

Decent insulated magnet wire



Catalog here:


AWG 12 copper bare is 0.0808 (nom)

single build is 0.0825 (i.e. the insulation is 8.5 mils (0.2 mm) thick

heavy build is 0.0842 is twice as thick. (0.4mm)


most plastics have breakdown strength of 20 kV/mm or more, especially
for thin layers.

PTFE (Teflon) and Polyimide (Kapton) are a lot better (100 kV/mm)

Polyester (Mylar) is in between (50kV/mm)




Note that thinner layers have a higher breakdown voltage per mm (that
is, you might find that a layer that's 0.1 mm and 1mm have almost the
same breakdown voltage)

Formvar is about 11kV as typically applied to wire.

On 01/26/2021 3:30 PM David Eckhardt <davearea51a@...> wrote:


Those wound with the #12 enameled solid conductor do not take power with
my ant/feedline impedances resulting in discharges between bifilar pairs
(not between individual bifilar windings). Also, the green wire of
unknown insulation does not take power. So, those CMCs wound with solid
conductor are coming apart and being rewound in some fashion or another
with the DavisRF "antenna" wire which seems to take power to at least

1.2

kW. Your mileage may vary with different impedances presented to the
chokes.

Those frequencies on which I tried the CMCs at power are:
3.8 MHz 24 - j56
7.15 MHz 493 - j740
Impedances noted are measured at the shack end of the parallel wire
feedline.

Dave

The following files have been uploaded to the Files area of the
[email protected] group.

? ? - /Absolute Beginner Guide to The
? ? NanoVNA/Absolute_Beginner_Guide_NanoVNA_v1_6.pdf
? ? </g/nanovna-users/files/Absolute%20Beginner%20Guide%20to%20The%20NanoVNA/Absolute_Beginner_Guide_NanoVNA_v1_6.pdf>

*By:* Martin J.K.

*Description:*
New in version 1.6: - expanded firmware upgrade and the driver
installation section - some typo errors corrected. Thanks to everyone who
points me to typos and email good suggestions for improvement.