Which ferrite material for 3-30MHz balun?...

[Joerg]

Attention, this is a non-political post, for a change

Getting back into ham radio after a decades-long hiatus I need to make a
balun for 3-30MHz. Essentially just a glorified common-mode choke and
preferably without an extra 3rd magnetizing winding. Realistically I
won\'t use more than 200W but it would be nice if it can take more. There
are a bunch of new materials that showed up which I can\'t remember from
the 80\'s. From some research on the web it seems 61-material is a really
good contender when it comes to low core loss yet acceptable
permeability. So I was thinking of getting an FT240-61 core. What do
thee think?

Main reason I ask is that I remember having blown up a few baluns back
in the days and I don\'t want this thing to cause a meltdown here in
bone-dry California.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Clifford Heath]

On 19/10/20 9:33 am, Joerg wrote:

Attention, this is a non-political post, for a change

Getting back into ham radio after a decades-long hiatus I need to make a
balun for 3-30MHz. Essentially just a glorified common-mode choke and
preferably without an extra 3rd magnetizing winding. Realistically I
won\'t use more than 200W but it would be nice if it can take more. There
are a bunch of new materials that showed up which I can\'t remember from
the 80\'s. From some research on the web it seems 61-material is a really
good contender when it comes to low core loss yet acceptable
permeability. So I was thinking of getting an FT240-61 core. What do
thee think?

Main reason I ask is that I remember having blown up a few baluns back
in the days and I don\'t want this thing to cause a meltdown here in
bone-dry California.

The EFHW antenna enthusiasts on the Facebook group seem to use type 43
material. Two FT240-43 toroids handle over 100W, and three, up to 1kW
(not sure about duty cycles, probably SSB ham chatter). Type 52 is
another option, lower loss but lower power handling.

You might find more in this article (which I haven\'t read in depth):
https://lookaside.fbsbx.com/file/EFHW%20German%20Article.pdf

Clifford Heath

 

[bitrex]

On 10/18/2020 6:33 PM, Joerg wrote:

Attention, this is a non-political post, for a change

Getting back into ham radio after a decades-long hiatus I need to make a
balun for 3-30MHz. Essentially just a glorified common-mode choke and
preferably without an extra 3rd magnetizing winding. Realistically I
won\'t use more than 200W but it would be nice if it can take more. There
are a bunch of new materials that showed up which I can\'t remember from
the 80\'s. From some research on the web it seems 61-material is a really
good contender when it comes to low core loss yet acceptable
permeability. So I was thinking of getting an FT240-61 core. What do
thee think?

Main reason I ask is that I remember having blown up a few baluns back
in the days and I don\'t want this thing to cause a meltdown here in
bone-dry California.

Looking at the curves for 61 material the losses don\'t dominate till
beyond 50 MHz. 43 material has higher initial permeability but craps out
much too early.

Maybe 52 material as compromise:

<https://www.fair-rite.com/52-material-data-sheet/>

 

[Gerhard Hoffmann]

Am 19.10.20 um 00:33 schrieb Joerg:

Attention, this is a non-political post, for a change

Getting back into ham radio after a decades-long hiatus I need to make a
balun for 3-30MHz. Essentially just a glorified common-mode choke and
preferably without an extra 3rd magnetizing winding. Realistically I
won\'t use more than 200W but it would be nice if it can take more. There
are a bunch of new materials that showed up which I can\'t remember from
the 80\'s. From some research on the web it seems 61-material is a really
good contender when it comes to low core loss yet acceptable
permeability. So I was thinking of getting an FT240-61 core. What do
thee think?

Main reason I ask is that I remember having blown up a few baluns back
in the days and I don\'t want this thing to cause a meltdown here in
bone-dry California.

Amidon red?
Amidon is just a box mover. IIRC its Micrometals, really.

I have one 102 mm od 57mm id 33 mm high. Probably won\'t ever use it.
It has some weight, but if you want it...

cheers, Gerhard

 

[bitrex]

On 10/18/2020 7:03 PM, Clifford Heath wrote:

On 19/10/20 9:33 am, Joerg wrote:
Attention, this is a non-political post, for a change

Getting back into ham radio after a decades-long hiatus I need to make
a balun for 3-30MHz. Essentially just a glorified common-mode choke
and preferably without an extra 3rd magnetizing winding. Realistically
I won\'t use more than 200W but it would be nice if it can take more.
There are a bunch of new materials that showed up which I can\'t
remember from the 80\'s. From some research on the web it seems
61-material is a really good contender when it comes to low core loss
yet acceptable permeability. So I was thinking of getting an FT240-61
core. What do thee think?

Main reason I ask is that I remember having blown up a few baluns back
in the days and I don\'t want this thing to cause a meltdown here in
bone-dry California.

The EFHW antenna enthusiasts on the Facebook group seem to use type 43
material. Two FT240-43 toroids handle over 100W, and three, up to 1kW
(not sure about duty cycles, probably SSB ham chatter). Type 52 is
another option, lower loss but lower power handling.

You might find more in this article (which I haven\'t read in depth):
https://lookaside.fbsbx.com/file/EFHW%20German%20Article.pdf

Clifford Heath

This author seems to prefer 31 material:

<http://audiosystemsgroup.com/CoaxChokesPPT.pdf>

 

[amdx]

On 10/18/2020 5:33 PM, Joerg wrote:

Attention, this is a non-political post, for a change

Getting back into ham radio after a decades-long hiatus I need to make
a balun for 3-30MHz. Essentially just a glorified common-mode choke
and preferably without an extra 3rd magnetizing winding. Realistically
I won\'t use more than 200W but it would be nice if it can take more.
There are a bunch of new materials that showed up which I can\'t
remember from the 80\'s. From some research on the web it seems
61-material is a really good contender when it comes to low core loss
yet acceptable permeability. So I was thinking of getting an FT240-61
core. What do thee think?

Main reason I ask is that I remember having blown up a few baluns back
in the days and I don\'t want this thing to cause a meltdown here in
bone-dry California.

  From all my reading of other peoples work, I have not seen where
anyone uses

material 61 for a multiband ham antenna.  From one of W8ji balun pages,
one criteria he uses is

curie temperature. He uses 75 for receiving antennas, but because of
it\'s lower curie temperature,

 not for power baluns. Sorry in my 10 minutes searching, I couldn\'t
find what material he does use.

Mikek



--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus

 

[legg]

On Mon, 19 Oct 2020 01:16:25 +0200, Gerhard Hoffmann <dk4xp@arcor.de>
wrote:

Am 19.10.20 um 00:33 schrieb Joerg:
Attention, this is a non-political post, for a change

Getting back into ham radio after a decades-long hiatus I need to make a
balun for 3-30MHz. Essentially just a glorified common-mode choke and
preferably without an extra 3rd magnetizing winding. Realistically I
won\'t use more than 200W but it would be nice if it can take more. There
are a bunch of new materials that showed up which I can\'t remember from
the 80\'s. From some research on the web it seems 61-material is a really
good contender when it comes to low core loss yet acceptable
permeability. So I was thinking of getting an FT240-61 core. What do
thee think?

Main reason I ask is that I remember having blown up a few baluns back
in the days and I don\'t want this thing to cause a meltdown here in
bone-dry California.

Amidon red?
Amidon is just a box mover. IIRC its Micrometals, really.

I have one 102 mm od 57mm id 33 mm high. Probably won\'t ever use it.
It has some weight, but if you want it...

cheers, Gerhard

That\'s Micrometals #2 material. Anything requiring power transfer.
There are other carbonyl mixes that are better towards 30MHz,
but they\'re special order.

RL

 

[bitrex]

On 10/18/2020 8:40 PM, legg wrote:

On Mon, 19 Oct 2020 01:16:25 +0200, Gerhard Hoffmann <dk4xp@arcor.de
wrote:

Am 19.10.20 um 00:33 schrieb Joerg:
Attention, this is a non-political post, for a change

Getting back into ham radio after a decades-long hiatus I need to make a
balun for 3-30MHz. Essentially just a glorified common-mode choke and
preferably without an extra 3rd magnetizing winding. Realistically I
won\'t use more than 200W but it would be nice if it can take more. There
are a bunch of new materials that showed up which I can\'t remember from
the 80\'s. From some research on the web it seems 61-material is a really
good contender when it comes to low core loss yet acceptable
permeability. So I was thinking of getting an FT240-61 core. What do
thee think?

Main reason I ask is that I remember having blown up a few baluns back
in the days and I don\'t want this thing to cause a meltdown here in
bone-dry California.

Amidon red?
Amidon is just a box mover. IIRC its Micrometals, really.

I have one 102 mm od 57mm id 33 mm high. Probably won\'t ever use it.
It has some weight, but if you want it...

cheers, Gerhard


That\'s Micrometals #2 material. Anything requiring power transfer.
There are other carbonyl mixes that are better towards 30MHz,
but they\'re special order.

RL

#2 material has worked well for me for _differential_ mode chokes at a
couple of MHz, in a differential pi filter, say, the distributed air gap
makes it more appropriate than a hard ferrite.

 

[Joerg]

On 10/18/20 4:03 PM, Clifford Heath wrote:

On 19/10/20 9:33 am, Joerg wrote:
Attention, this is a non-political post, for a change

Getting back into ham radio after a decades-long hiatus I need to make
a balun for 3-30MHz. Essentially just a glorified common-mode choke
and preferably without an extra 3rd magnetizing winding. Realistically
I won\'t use more than 200W but it would be nice if it can take more.
There are a bunch of new materials that showed up which I can\'t
remember from the 80\'s. From some research on the web it seems
61-material is a really good contender when it comes to low core loss
yet acceptable permeability. So I was thinking of getting an FT240-61
core. What do thee think?

Main reason I ask is that I remember having blown up a few baluns back
in the days and I don\'t want this thing to cause a meltdown here in
bone-dry California.

The EFHW antenna enthusiasts on the Facebook group seem to use type 43
material. Two FT240-43 toroids handle over 100W, and three, up to 1kW
(not sure about duty cycles, probably SSB ham chatter). Type 52 is
another option, lower loss but lower power handling.

43 is also my goto material but for EMI cases. For this application it
has too much resistive losses.

You might find more in this article (which I haven\'t read in depth):
https://lookaside.fbsbx.com/file/EFHW%20German%20Article.pdf

\"Arcticle isn\'t available\". I guess only for Facebook members. Only over
my dead body

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joerg]

On 10/18/20 4:28 PM, bitrex wrote:

On 10/18/2020 7:03 PM, Clifford Heath wrote:
On 19/10/20 9:33 am, Joerg wrote:
Attention, this is a non-political post, for a change

Getting back into ham radio after a decades-long hiatus I need to
make a balun for 3-30MHz. Essentially just a glorified common-mode
choke and preferably without an extra 3rd magnetizing winding.
Realistically I won\'t use more than 200W but it would be nice if it
can take more. There are a bunch of new materials that showed up
which I can\'t remember from the 80\'s. From some research on the web
it seems 61-material is a really good contender when it comes to low
core loss yet acceptable permeability. So I was thinking of getting
an FT240-61 core. What do thee think?

Main reason I ask is that I remember having blown up a few baluns
back in the days and I don\'t want this thing to cause a meltdown here
in bone-dry California.

The EFHW antenna enthusiasts on the Facebook group seem to use type 43
material. Two FT240-43 toroids handle over 100W, and three, up to 1kW
(not sure about duty cycles, probably SSB ham chatter). Type 52 is
another option, lower loss but lower power handling.

You might find more in this article (which I haven\'t read in depth):
https://lookaside.fbsbx.com/file/EFHW%20German%20Article.pdf

Clifford Heath

This author seems to prefer 31 material:

http://audiosystemsgroup.com/CoaxChokesPPT.pdf

Yes, 31 is often mentioned as close to 61 for balun performance. He does
mention 61 as well on sheet 42.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joerg]

On 10/18/20 4:09 PM, bitrex wrote:

On 10/18/2020 6:33 PM, Joerg wrote:
Attention, this is a non-political post, for a change

Getting back into ham radio after a decades-long hiatus I need to make
a balun for 3-30MHz. Essentially just a glorified common-mode choke
and preferably without an extra 3rd magnetizing winding. Realistically
I won\'t use more than 200W but it would be nice if it can take more.
There are a bunch of new materials that showed up which I can\'t
remember from the 80\'s. From some research on the web it seems
61-material is a really good contender when it comes to low core loss
yet acceptable permeability. So I was thinking of getting an FT240-61
core. What do thee think?

Main reason I ask is that I remember having blown up a few baluns back
in the days and I don\'t want this thing to cause a meltdown here in
bone-dry California.


Looking at the curves for 61 material the losses don\'t dominate till
beyond 50 MHz. 43 material has higher initial permeability but craps out
much too early.

Maybe 52 material as compromise:

https://www.fair-rite.com/52-material-data-sheet/

It really starts to drop off above 10MHz though. But could be ok as well.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joerg]

On 10/18/20 6:46 PM, bitrex wrote:

On 10/18/2020 8:40 PM, legg wrote:
On Mon, 19 Oct 2020 01:16:25 +0200, Gerhard Hoffmann <dk4xp@arcor.de
wrote:

Am 19.10.20 um 00:33 schrieb Joerg:
Attention, this is a non-political post, for a change

Getting back into ham radio after a decades-long hiatus I need to
make a
balun for 3-30MHz. Essentially just a glorified common-mode choke and
preferably without an extra 3rd magnetizing winding. Realistically I
won\'t use more than 200W but it would be nice if it can take more.
There
are a bunch of new materials that showed up which I can\'t remember from
the 80\'s. From some research on the web it seems 61-material is a
really
good contender when it comes to low core loss yet acceptable
permeability. So I was thinking of getting an FT240-61 core. What do
thee think?

Main reason I ask is that I remember having blown up a few baluns back
in the days and I don\'t want this thing to cause a meltdown here in
bone-dry California.

Amidon red?
Amidon is just a box mover. IIRC its Micrometals, really.

I have one 102 mm od  57mm id  33 mm high. Probably won\'t ever use it.
It has some weight, but if you want it...

Amidon red is my go-to material for resonant stuff at the lower end of
HF and also for voltage-mode baluns. However, it\'s not very suitable for
current-mode.

cheers, Gerhard


That\'s Micrometals #2 material. Anything requiring power transfer.
There are other carbonyl mixes that are better towards 30MHz,
but they\'re special order.

RL


#2 material has worked well for me for _differential_ mode chokes at a
couple of MHz, in a differential pi filter, say, the distributed air gap
makes it more appropriate than a hard ferrite.

Yup. But not for a glorified CM choke.

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Joerg]

On 10/18/20 5:22 PM, amdx wrote:

On 10/18/2020 5:33 PM, Joerg wrote:
Attention, this is a non-political post, for a change

Getting back into ham radio after a decades-long hiatus I need to make
a balun for 3-30MHz. Essentially just a glorified common-mode choke
and preferably without an extra 3rd magnetizing winding. Realistically
I won\'t use more than 200W but it would be nice if it can take more.
There are a bunch of new materials that showed up which I can\'t
remember from the 80\'s. From some research on the web it seems
61-material is a really good contender when it comes to low core loss
yet acceptable permeability. So I was thinking of getting an FT240-61
core. What do thee think?

Main reason I ask is that I remember having blown up a few baluns back
in the days and I don\'t want this thing to cause a meltdown here in
bone-dry California.

  From all my reading of other peoples work, I have not seen where
anyone uses

material 61 for a multiband ham antenna.  From one of W8ji balun pages,
one criteria he uses is

curie temperature. He uses 75 for receiving antennas, but because of
it\'s lower curie temperature,

He actually recommends, among other things, 61:

http://www.w8ji.com/core_selection.htm

Quote \"At higher power levels, it is necessary to move to lower loss
tangent and higher curie temperature materials like 65, 61, or (in
extreme cases) 43 materials.”

Not sure why he recommend 43 though because that\'s lossy. Gets hot.

 not for power baluns. Sorry in my 10 minutes searching, I couldn\'t
find what material he does use.

Mikek

--
Regards, Joerg

http://www.analogconsultants.com/

 

[Clifford Heath]

On 19/10/20 2:43 pm, Joerg wrote:

On 10/18/20 4:03 PM, Clifford Heath wrote:
On 19/10/20 9:33 am, Joerg wrote:
Attention, this is a non-political post, for a change

Getting back into ham radio after a decades-long hiatus I need to
make a balun for 3-30MHz. Essentially just a glorified common-mode
choke and preferably without an extra 3rd magnetizing winding.
Realistically I won\'t use more than 200W but it would be nice if it
can take more. There are a bunch of new materials that showed up
which I can\'t remember from the 80\'s. From some research on the web
it seems 61-material is a really good contender when it comes to low
core loss yet acceptable permeability. So I was thinking of getting
an FT240-61 core. What do thee think?

Main reason I ask is that I remember having blown up a few baluns
back in the days and I don\'t want this thing to cause a meltdown here
in bone-dry California.

The EFHW antenna enthusiasts on the Facebook group seem to use type 43
material. Two FT240-43 toroids handle over 100W, and three, up to 1kW
(not sure about duty cycles, probably SSB ham chatter). Type 52 is
another option, lower loss but lower power handling.


43 is also my goto material but for EMI cases. For this application it
has too much resistive losses.


You might find more in this article (which I haven\'t read in depth):
https://lookaside.fbsbx.com/file/EFHW%20German%20Article.pdf


\"Arcticle isn\'t available\". I guess only for Facebook members. Only over
my dead body

Ahh, sorry I don\'t know about that. The article seems to have been
removed since I posted it. My downloaded copy is now here:
<https://www.dropbox.com/s/lze82hwbbhhxcen/EFHW%20German%20Article.pdf?dl=0>

CH

 

[Michael Terrell]

On Sunday, October 18, 2020 at 6:33:23 PM UTC-4, Joerg wrote:

Attention, this is a non-political post, for a change

Getting back into ham radio after a decades-long hiatus I need to make a
balun for 3-30MHz. Essentially just a glorified common-mode choke and
preferably without an extra 3rd magnetizing winding. Realistically I
won\'t use more than 200W but it would be nice if it can take more. There
are a bunch of new materials that showed up which I can\'t remember from
the 80\'s. From some research on the web it seems 61-material is a really
good contender when it comes to low core loss yet acceptable
permeability. So I was thinking of getting an FT240-61 core. What do
thee think?

Main reason I ask is that I remember having blown up a few baluns back
in the days and I don\'t want this thing to cause a meltdown here in
bone-dry California.

Fair-Rite made Amidon toroids.
Amidon used to print a nice databook that sold for about $15. All I find now is the datasheet that the always sent with an order. <http://www.amidoncorp.com/product_images/Amidon-Tech-Data-Flyer-v19.pdf> This indicates that #2 is the only material covering the desired range, but it was created in 2001. The Amidon cores are available up to 5.2\" OD and a 3.08\" ID. <http://www.amidoncorp.com/2-material-iron-powder-toroids/>

<https://people.zeelandnet.nl/wgeeraert/ferrietUK.htm> has a lot of materials that might help.

 

[Jeff Liebermann]

On Sun, 18 Oct 2020 15:33:15 -0700, Joerg <news@analogconsultants.com>
wrote:

>Attention, this is a non-political post, for a change

I take it that you and your house survived the fires. Congrats. Same
here except the fire came within 1400 feet of my back door.

Getting back into ham radio after a decades-long hiatus I need to make a
balun for 3-30MHz.

1:1 Balun or something else like a 4:1 ??

Essentially just a glorified common-mode choke and
preferably without an extra 3rd magnetizing winding. Realistically I
won\'t use more than 200W

200W CW or PEP? The average power is different.
Duty cycle?

>but it would be nice if it can take more.

How much more power? For how long? Duty cycle?

There
are a bunch of new materials that showed up which I can\'t remember from
the 80\'s.
From some research on the web it seems 61-material is a really
good contender when it comes to low core loss yet acceptable
permeability. So I was thinking of getting an FT240-61 core. What do
thee think?

These might help:
<http://k9yc.com/FerriteDataHF.pdf>
<http://k9yc.com/Toroid61Data-2.pdf>
<http://k9yc.com/RFI-Ham.pdf>
<http://k9yc.com/2018Cookbook.pdf> (He uses #31 here).
Might be more buried on his web pile:
<http://k9yc.com/publish.htm>

I have four FT240-31 toroids that I was going to use in an HF antenna
project which was interrupted by ummm... everything.
<https://www.fair-rite.com/31-material-data-sheet/>
<https://www.fair-rite.com/61-material-data-sheet/>
<http://www.amidoncorp.com/ft-240-31/>
No, you can\'t have them. I\'m not sure what to recommend for your
antenna project.

Looking at the Far-Right data sheets,
<https://www.fair-rite.com/materials/>
I would guess(tm) that #31 is better than #61 because of the much
higher initial permeability. That translates into needing few turns
of wire for the same inductance. Getting a sufficiently large number
of wire turns, or more likely coax cable turns, through the toroid
hole might be a problem.

It doesn\'t help that the loss tangent is specified at 100 KHz for #31
and at 10 MHz for #61. Just to make things weird, #31 includes this
cryptic statement:
This material does not have the dimensional resonance
limitations associated with conventional MZn ferrite
materials.
What\'s a \"dimensional resonance limitation\"?

Since power dissipation might be a problem, #61 Curie Temp is >300C,
while #31 is >150C. If you\'re planning on running the balun hot, this
might be a consideration making #61 the better material.

Send Jim (K9YC) an email and maybe he can help. Note that he just
recently returned from a rather protracted fire evacuation and might
be rather busy.

Full disclosure: I bought the four T240-31 toroids from Jim at a
discounted price in a group buy through the local radio club.

Main reason I ask is that I remember having blown up a few baluns back
in the days and I don\'t want this thing to cause a meltdown here in
bone-dry California.

Hang a galvanized steel bucket under the balun to catch any flaming
material selection errors. Or, perhaps consider the possibilities of
QRP.



--
Jeff Liebermann jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

 

[Piglet]

On 19/10/2020 07:58, Jeff Liebermann wrote:

It doesn\'t help that the loss tangent is specified at 100 KHz for #31
and at 10 MHz for #61. Just to make things weird, #31 includes this
cryptic statement:
This material does not have the dimensional resonance
limitations associated with conventional MZn ferrite
materials.
What\'s a \"dimensional resonance limitation\"?

I guess they mean magneto-striction induced mechanical resonance causing
cracking? I once used some small square-loop material toroids where the
datasheet said to avoid some frequencies to avoid cracking - these were
small cores and the frequencies to avoid were in the low hundreds kHz.
Shouldn\'t be a problem at OPs 3-30MHz.

piglet

 

[Jan Panteltje]

On a sunny day (Sun, 18 Oct 2020 15:33:15 -0700) it happened Joerg
<news@analogconsultants.com> wrote in <hv3u5cF49h2U1@mid.individual.net>:

>Attention, this is a non-political post, for a change

I recently found
uk.radio.amateur.moderated
may be worth asking there.
Still active and no noise!


As to antenna matching, antenna tuners can match any piece of wire...
I have a small QRP one... kit from ebay...
http://panteltje.com/pub/ebay_QRP_antenna_tuner_IXIMG_0552.JPG
search ebay for \"QRP MANUAL DAYS ANTENNA TUNER TUNE DIY KIT 1 - 30 MHZ\"
100W would set it on fire.
But think if you look for higher power they will have it, else alieexpress:
https://www.aliexpress.com/w/wholesale-automatic-antenna-tuner.html

why bother with single cores...


Bought some
Micrometals Amidon T80-2 Iron Powder Toroidal
for experiments long time ago:
https://toroids.info/T80-2.php

There are a lot of Usenet amateur radio groups:
http://www.panteltje.com/pub/usenet_amateur_radio_groups_IXIMG_0550.JPG
the green ones are dead (no longer in active list on nntp.aioe.org),
the red one is new,
and the blue one is the one I am subscribed to ATM,
have not checked the other ones for activity.


For the 10m band I have a GPA, no balun needed, 150 W PEP, Ranger RCI2970DX.
Not much used these days.
Nothing for lower frequencies than that.

 

[Bill Sloman]

On Monday, October 19, 2020 at 9:33:23 AM UTC+11, Joerg wrote:

Attention, this is a non-political post, for a change

Getting back into ham radio after a decades-long hiatus I need to make a
balun for 3-30MHz. Essentially just a glorified common-mode choke and
preferably without an extra 3rd magnetizing winding. Realistically I
won\'t use more than 200W but it would be nice if it can take more. There
are a bunch of new materials that showed up which I can\'t remember from
the 80\'s. From some research on the web it seems 61-material is a really
good contender when it comes to low core loss yet acceptable
permeability. So I was thinking of getting an FT240-61 core. What do
thee think?

Main reason I ask is that I remember having blown up a few baluns back
in the days and I don\'t want this thing to cause a meltdown here in
bone-dry California.

Nickel-Zinc ferrites are a lot more resistive than MnZn ferrites and correspondingly less likely to get hot.

A balun is essentially a transmission line transformer, and the higher frequencies don\'t get that far into the core material.

--
Bill Sloman, Sydney

 

[bitrex]

On 10/19/2020 5:34 AM, Jan Panteltje wrote:

On a sunny day (Sun, 18 Oct 2020 15:33:15 -0700) it happened Joerg
news@analogconsultants.com> wrote in <hv3u5cF49h2U1@mid.individual.net>:

Attention, this is a non-political post, for a change

I recently found
uk.radio.amateur.moderated
may be worth asking there.
Still active and no noise!


As to antenna matching, antenna tuners can match any piece of wire...
I have a small QRP one... kit from ebay...
http://panteltje.com/pub/ebay_QRP_antenna_tuner_IXIMG_0552.JPG
search ebay for \"QRP MANUAL DAYS ANTENNA TUNER TUNE DIY KIT 1 - 30 MHZ\"
100W would set it on fire.
But think if you look for higher power they will have it, else alieexpress:
https://www.aliexpress.com/w/wholesale-automatic-antenna-tuner.html

why bother with single cores...


Bought some
Micrometals Amidon T80-2 Iron Powder Toroidal
for experiments long time ago:
https://toroids.info/T80-2.php

There are a lot of Usenet amateur radio groups:
http://www.panteltje.com/pub/usenet_amateur_radio_groups_IXIMG_0550.JPG
the green ones are dead (no longer in active list on nntp.aioe.org),
the red one is new,
and the blue one is the one I am subscribed to ATM,
have not checked the other ones for activity.


For the 10m band I have a GPA, no balun needed, 150 W PEP, Ranger RCI2970DX.
Not much used these days.
Nothing for lower frequencies than that.

The #2 carbonyl iron material is a nice all-rounder material for just
regular inductors in the low MHz range, for inductors that need to store
energy. The only bummer is its pretty low Al value.

The #8 material is similar but with a nice boost to the Al value and a
little lower transition frequency, it\'s about 4 times the price though.

Commmon mode chokes don\'t need to store energy so a hard ferrite is more
appropriate, you can have Al values of like a thousand rather than say, 25.