Author Topic: Winding an Un-Un  (Read 9522 times)

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Offline A.Z.

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Re: Winding an Un-Un
« Reply #75 on: May 21, 2022, 07:53:31 am »
 

Offline joeqsmith

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Re: Winding an Un-Un
« Reply #76 on: May 21, 2022, 02:09:30 pm »
With no goals and constraints, here is a coaxial wound 9:1 UnUn.    Performance is very poor.

I'll refrain

https://cromwell-intl.com/radio/9-1-unun/

and also

http://www.warc.asn.au/wp-content/uploads/2018/09/tube-baluns.pdf

The first link shows the typical 9:1 UnUn while your second link is about BalUns.   I assumed from the title, the goal was to make an UnUn.  Specifically a 9:1.  The OP was only testing from 3-30MHz,  with a worse case VSWR of 1.4:1.   

Again, I want to be clear that I have no use for such a device and am only playing around.  Electronics is one of my hobbies and I enjoy experimenting.  That does not mean that I like to copy and paste.   Do a search on youtube for 1:9 unun.   Outside of different colors of wire and a few different material selections, they all are similar to the one shown in your first link.  Once in a while, someone may even show a little data from theirs.   That's nothing I have any interest in.  I would rather spend my time experiment with other ideas and fail.  That last coaxial core would work well below 1MHz but the high end suffered.   Time for some new material. 

Let's see what you have put together. 

****
I have accumulated a box of materials over the years.  Some I kept marked, others are unknown.   Sorting through them to see what else I have that could work, that 45mm core looks very interesting.   I have another that is roughly 37mm that appears to be the same material but not a matched set.   Easy enough to try it with the OPs construction but going with the twin core would certainly help with the higher end.    The core to the far right is another that would be very interesting to try.   
« Last Edit: May 21, 2022, 04:28:26 pm by joeqsmith »
 

Offline A.Z.

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Re: Winding an Un-Un
« Reply #77 on: May 21, 2022, 04:49:46 pm »
Joe, probably I was unclear; the first link in the message you quoted, shows how to properly calculate the windings and also shows that it's important to know the characteristics of the core material one is using, trial and error isn't exactly the best line of action, in my humble opinion; then, as for the second link, I posted it mainly to show the "flattening" effect (on the SWR curve) which can be obtained by placing a capacitor across the winding, no miracles by the way, but if one starts knowing the core material and calculating the windings, the resulting transformer will be in the ballpark and may just need some tiny adjustment, at that point, willing to flatten the response curve (given it will be needed) would just mean adding a capacitor and adjusting its value

hope to have made my point more clear now
« Last Edit: May 21, 2022, 04:55:56 pm by A.Z. »
 

Offline joeqsmith

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Re: Winding an Un-Un
« Reply #78 on: May 21, 2022, 04:51:26 pm »
Notice how the OPs purchased unit is starting to peak back up below 3MHz.   These other parts I have should be good below a MHz. 
https://www.eevblog.com/forum/rf-microwave/winding-an-un-un/msg4174312/#msg4174312

Starting with the smaller 36mm core (larger than what I have shown so far),  using the resistor substitution box set to 225, 450 & 900 ohms.   I swept from 400Khz to 4MHz.   Again, I'm just using that box of resistors to get some idea how the transformer behaves.   At 4MHz the LiteVNA is showing a VSWR of 1.32:1 which I expect if due to the load.

Offline A.Z.

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Re: Winding an Un-Un
« Reply #79 on: May 21, 2022, 04:59:01 pm »
Either a #43 or a #61 core will get at least down to around 1MHz, although the #61 will require more turns, but if one doesn't know the core material, then it will just become a wild guess game :P
 

Offline joeqsmith

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Re: Winding an Un-Un
« Reply #80 on: May 21, 2022, 05:02:54 pm »
Why would you think I had not made any calculations?  Note he just provides the same basics that everyone else shows.  It's nothing new.   Same for measuring the cores I have.  Do you really think I am just randomly grabbing parts and winding them up?   :palm:   

Again, looking forward to seeing what YOU have done?  Google foo counts for nothing...

Swapping out the load for the 1/4W axial,  the low end VSWR now looks like I would expect.  Good for the radio guys playing in the 160 meter band. 

Offline joeqsmith

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Re: Winding an Un-Un
« Reply #81 on: May 21, 2022, 05:14:25 pm »
Sweeping the core from 1.8MHz to 29.7MHz.   I doubt the radio hobbyist do much with UnUns outside of that range.  Not bad for guessing... :-DD 

Offline A.Z.

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Re: Winding an Un-Un
« Reply #82 on: May 21, 2022, 05:18:06 pm »
Oh, so your point is "show me yours"; sorry but I stopped building stuff quite some years ago, and... yes, reading what you wrote, my impression was that you were picking "random" cores from your "junk box", winding some turns and then playing with VNA, then maybe I was under the wrong impression
 

Offline joeqsmith

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Re: Winding an Un-Un
« Reply #83 on: May 21, 2022, 05:37:40 pm »
Oh, so your point is "show me yours"; sorry but I stopped building stuff quite some years ago, and... yes, reading what you wrote, my impression was that you were picking "random" cores from your "junk box", winding some turns and then playing with VNA, then maybe I was under the wrong impression

It wasn't a point but a request to see what you personally had done.  I was under the impression you were an armchair engineer and was wondering if I had the wrong impression.

Even if I am just a pretty good guesser in your eyes and I can live with that.

Offline A.Z.

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Re: Winding an Un-Un
« Reply #84 on: May 21, 2022, 06:51:08 pm »
Oh, so your point is "show me yours"; sorry but I stopped building stuff quite some years ago, and... yes, reading what you wrote, my impression was that you were picking "random" cores from your "junk box", winding some turns and then playing with VNA, then maybe I was under the wrong impression

It wasn't a point but a request to see what you personally had done.  I was under the impression you were an armchair engineer and was wondering if I had the wrong impression.

Even if I am just a pretty good guesser in your eyes and I can live with that.

well, all in all your impression was correct, due to personal issues, as of today I AM an "armchair" engineer ... and almost a "wheelchair" one, but I was lucky

Just to be clear, I'm not asking for anything at all, I'm able to stand to my ideas, not asking for whatever, so feel free to criticize, I was not "begging"; hope it's clear now


« Last Edit: May 21, 2022, 08:57:03 pm by A.Z. »
 

Offline joeqsmith

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Re: Winding an Un-Un
« Reply #85 on: May 21, 2022, 09:56:25 pm »
Electronics is the least physically demanding hobby I have.  Most of the time I spend sitting in a chair at the bench or my desk. 

My cheap resistor substitution box.  And now you see where a lot of the error comes from.   :-DD   All part of the fun.

Rebuilt the coaxial transformer using 18AWG silver coated Teflon wire.  Good for a KV.   Time for a much larger load....

****
Used a combination of wire wound resistors along with the LiteVNA to pick a few sweet spots in the ham bands with decent VSWR.   
« Last Edit: May 22, 2022, 12:17:50 am by joeqsmith »
 

Offline joeqsmith

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Re: Winding an Un-Un
« Reply #86 on: May 22, 2022, 01:53:18 am »
I'll replace the little VSWR meter and smaller coax with a section of larger coax before turning  it up further. 

Offline joeqsmith

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Re: Winding an Un-Un
« Reply #87 on: May 22, 2022, 03:41:11 pm »
I had tried the larger coax and let it run at higher power levels for about an hour.  Once again the  Brymen meter, even with the one bead is showing about 10C of error.  Once I turned the amplifier off to see the actual core temperatures, they were around 28C.   
« Last Edit: May 22, 2022, 03:49:12 pm by joeqsmith »
 

Offline joeqsmith

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Re: Winding an Un-Un
« Reply #88 on: May 22, 2022, 03:56:32 pm »
Last attempt was to test that last larger 44mm core.  After making a few measurements, I believe this part is made from HF90.  I believe that last smaller core was the same material.   This is also 5 turns with 18AWG silver coated Teflon insulated wire.   

Showing VSWR using the axial resistor from 400kHz to 4MHz and again from 1.8MHz to 29.7MMHz.   

Offline joeqsmith

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Re: Winding an Un-Un
« Reply #89 on: May 22, 2022, 04:02:49 pm »
The load is a problem so I ran the last two transformers back-to-back.  I rebuilt an old 100W JWF attenuator a while back and will use this as the load.   With forced air cooling, I have ran it over 200 Watts.

Showing VSWR from 1.8-29.7MHz with the terminated attenuator and two transformers.   Much better than the WW resistors....

Offline joeqsmith

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Re: Winding an Un-Un
« Reply #90 on: May 22, 2022, 04:27:13 pm »
The Fluke 189s were used to measure the temperature of the two transformers (without additional ferrite).  At 30MHz the VSWR is roughly 1.5.  Even at 100 Watts the HF90 core is already starting to heat up.   It's warm to the touch.   

That second picture was taken after about an hour.  Obviously the radio hobbyist is not running at 100% duty cycle.   Or are they??!! :-DD   

The other transformer is 8 pcs of 31mm HF70 material.    Guessing that TDK HF90 would be a good choice but I think they have been obsoleting some of this material.

Offline joeqsmith

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Re: Winding an Un-Un
« Reply #91 on: May 22, 2022, 05:06:09 pm »
Removing the old SWR meter and running at about 300Watts.  The amplifier isn't going to bat an eye at these levels.   The Kapton tape has started to smell and delaminate.   Touching the core, yeah, it's that hot!  I cut the power and measured the core temps after about a minute and it's still well over 100C.   The 8-core unit stayed nice and cool.

Well, not sure if any of that was helpful or not.  Entertaining for me anyway. 

Offline T3sl4co1l

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Re: Winding an Un-Un
« Reply #92 on: May 22, 2022, 06:04:41 pm »
Time to invest in some silicone adhesive polyimide tape!

That it's available with rubber adhesive surely must be some kind of joke... :P

Tim
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Electronic design, from concept to prototype.
Bringing a project to life?  Send me a message!
 

Offline joeqsmith

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Re: Winding an Un-Un
« Reply #93 on: May 22, 2022, 07:08:24 pm »
I've use Kapton tape for all sorts of projects.  Some can be used above 300C.  I will use it as an insulator when modifying boards as I can solder components laying on the tape.   
We had a PCB made from polyimide for a high temp application.   Good stuff.   Check 3Ms catalog:

https://multimedia.3m.com/mws/media/1705914O/3m-high-temperature-tapes-product-selection-guide.pdf

Before cleaning up the mess, I did flip the two transformers so I was driving the T90 core with the load on the T70.  I placed the VSWR meter back in-line.  I also flipped the meters at TCs.    Ran it at about 100W for a while and the single T90 core started to heat up right away.  VSWR was a wash.  So nothing funny going on there. 

Offline joeqsmith

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Re: Winding an Un-Un
« Reply #94 on: May 25, 2022, 12:54:38 pm »
Thinking to purchase a commercial UnUn to see how it performs.   Looking around many are receive only or kits.   I would rather stay away from a kit.  Not that I'm concerned about assembling one, but it would raise questions if there was a problem. 

Any advice on such a product? 

Offline virtualparticles

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Re: Winding an Un-Un
« Reply #95 on: June 01, 2022, 12:05:51 pm »
The resistors are fine.  Carbon or metal film type axial resistors have a spiral stripe that becomes inductive up in the GHz (and even then, for fairly low R values, up to say 200-300 ohms; above which, lead capacitance dominates instead).

The stray wiring is not however!  Trim that tight and short between core and connector(s).

Tim

ok for the resistors, but the wiring is screwed, it is like having a bunch of random inductors connected to the unun :(

Just so! Here's a nice rule of thumb. a straight wire hanging in space has an inductance of about 20 nH/inch. The actual curve goes from about 12 nH/inch for 1/4" diameter wire to about 25 nH/inch for bond wires on a chip so 20 isn't a bad rule of thumb for most wire. When the inductance of the input wires become equal to 50 ohms reactance then things will start to fall apart rather quickly.
 

Offline joeqsmith

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Re: Winding an Un-Un
« Reply #96 on: June 05, 2022, 02:27:38 pm »
I bought a transformer kit and used it to make a 9:1 unun following these instructions:
http://vk6ysf.com/unun_9-1.htm

The 1.5kW Kit I used:
https://www.amazon.com/AEcreative-Amateur-Antenna-ferrite-Enameled/dp/B07LC1YTDM/ref=sr_1_15?crid=31JGB7BYSSFEW&keywords=9+1+unun&qid=1654438593&sprefix=9%3A1+%2Caps%2C92&sr=8-15

Video shows the buildup and testing.  I had started out with 12 turns and had I known, I would have tried the entire amount of wire they provided.  10 turns was a poor choice.   I doubt the whole 1.5kW.

Online bingo600

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Re: Winding an Un-Un
« Reply #97 on: June 09, 2022, 06:05:59 pm »
Since i just received my first HF station today (FT-991A) , this thread is "pure gold".
The layout of my Summerhouse & lot , will probably force me to use an EndFeed for the HF part.
I expect a EHFW at around 23m long ... I'd love to run 80/40/20/10 , i don't have room (space) for 160m.

If i'm luky i can get it 15..20 feet up in the feed end , and maybe 12..15 feet in the other.

I was expecting go get a "done" (Hyendfeed) to begin with , as i'd like to get going.
And maybe experiment later with some Horizontal L , as i have 3 trees up there.

I'm a little sad about the Hyendfeed only taking around 35W CW/Data (200W PEP) , but think it must be the 80m coil at the end that's the limiting factor.
I asked them if they'd make a 500W PEP , but they said they had no plans  :-\

Hyendfeed  Great rewiews
https://hyendcompany.nl/antenna/multiband_8040201510m/product/detail/3/HyEndFed_5_Band_Black_Clamp_MK3#prod

DIY
https://www.hfkits.com/product/10-15-20-40-80-endfed-antenna-kit/

Others
https://www.wireantennas.co.uk/hf/Half%20Wave%20End%20Fed%20Antenna?product_id=117

https://www.wireantennas.co.uk/hf/Half%20Wave%20End%20Fed%20Antenna?product_id=120

Ps: I have a GP for VHF/UHF

/Bingo
 

Offline Hamelec

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Re: Winding an Un-Un
« Reply #98 on: June 09, 2022, 08:30:34 pm »
@Bingo
..and don't forget it is also working on 15m.
I do not think that the 80m coil is the limiting factor - maybe they used a small toroid only.
Or is it out of band / bad SWR?
A FT240-43 should work..
73, Manfred
 

Offline A.Z.

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Re: Winding an Un-Un
« Reply #99 on: June 10, 2022, 08:06:56 am »
Since i just received my first HF station today (FT-991A) , this thread is "pure gold".
The layout of my Summerhouse & lot , will probably force me to use an EndFeed for the HF part.
I expect a EHFW at around 23m long ... I'd love to run 80/40/20/10 , i don't have room (space) for 160m.

If i'm luky i can get it 15..20 feet up in the feed end , and maybe 12..15 feet in the other.

Well, an EFHW, as the name says, needs to be 1/2 wave on the lowest frequency, so for the 40m band you'll need 20m of wire; now, you wrote you don't have enough room, in such a case, and also since the 991 has an internal ATU, did you consider a so-called "random wire" antenna instead of an EFHW ? Let me try an example; let's start from the wire lengths shown here (the green numbers down the page) and let's say we pick the 84' length (while a straight line is preferred, the wire could also be laid out with some [wide] angles both vertical and horizontal), such a size will allow to cover all bands from 80 to 10 meters, and while the antenna won't be so efficient on 80m being around 1/4 wave on that band, it will still work; such an antenna will require a counterpoise system, in this case a 17' (at least) run of insulated wire dropping down from the feedpoint will suffice (a section of wire may also lay down on ground if needed); add a 9:1 UnUn (you may use an FT240-43 in place of the FT140-43 if you want) followed by a choke, connect your coax and you'll have your multiband antenna; sure it won't be a "beam" but for a starter it will serve you honestly, then, as for all things, there's always room for improvements

my 2 cents

[edit]

For further informations and additional possible lengths for the "random" antenna, see here too

https://udel.edu/~mm/ham/randomWire/

HTH


« Last Edit: June 10, 2022, 09:39:03 am by A.Z. »
 


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