About Radio 55 Why we use Litz wire and silver plating
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- Опубликовано: 15 окт 2024
- In this video I talk about why Litz wire and silver plating is used at high frequency. Because of the property of 'self inductance' the current flowing in an AC circuit doesn't flow evenly throughout the area of a conductor. At higher frequencies the current flows predominantly just under the surface of the conductor and when we get into the megahertz range this 'skin depth' where the current flows is so shallow that the current can flow in the silver plating that's on the surface of the conductor.
I'm following this video with one on a similar vein were I talk about inductance but this is such a useful thing to understand I think it's worth driving home.
I hope you found this either helpful or entertaining.
Don't for get to leave your comments
Thanks for watching
Kind Regards ... Andy
gw0jxm
Very interesting. I am a full tech radio and electronics 63 yrs old and have learned something today. Thank-you!
Hey thanks for the comment, what do they say? 'You're never to old to learn.' Man I've got 69 turns on the coil and I'm still learning because I'm interested in everything. All the very best to you. . . Andy
Thanks for making that video. Filled in a few blanks for me. Wish i had known in greater depth these things years ago. Better now than never. Appreciated.
Your continuing efforts to relieve my ignorance are very much appreciated.
Even after 8 years it's still interessting 🙏.
Thanks
This is one very interesting subject Sir. The part that gets me is that the LITZ wire can perform some amazing things. The super special part is the wire can be braided and or weaved or a combination. This wire can really carry a lot of current and smile at the load. JUST CRAYZIE PHYSICS !!!!!
Andy, Thanks for sharing your vast experience with everyone. Your videos are so educational.
You are a great teacher with a wonderful technique in conveying information. Well done Andy
This video should be given in all arguments about audio cables, too. Actual science! (yay!). I thank You immeasurably, Sir.
Andy, you are the greatest teacher in the world, I wish there was a tech meet up, so we could learn so much more from you, I did not know you were a design engineer, you should do a youtube video, on your personal history with electronics, from your school days to now, it would be interesting, and give us your thoughts on where consumer electronics will be in the future, the BBC if that's what you call it, should do a documentary on you. Keep up the good work for years to come.
As always watch you videos and learn ,you do a great job
thankyou
Dennis from wis
Hi Andy, Thankyou for all the greatly informational and easy to follow ( I'm a newby to FM TX and radio) tutorials about radio electronics. I enjoy all of your videos, of any length. I like the technical info you impart, the HOW & WHY it is the way it is. Please keep the videos coming. Someone in Willamina, Oregon is watching. Thankyou, Cass.
thank -you for the excellent explanation of the effect this has been rolling around in me head for some time and your explanation on skin effect has been extremely helpful
Hi there... well you’re too kind. I know that there are some really knowledgeable folk out there that would make me look like a beginner but thanks for the complement, now if I could just get my head through the door I’d be OK. I have had an interesting time and I’d love to share some of my experiences but I'm just an ordinary guy and again I know that there are many much worthy guys than I but again thanks for the interest. And thanks to RUclips for making this all possible.
Regards...Andy
Hi Andy, your explcacion, is clear and simple, explain the effect of radio frequency currents on the surface of conductors, your explanation, shows the difference in cost between a connector and a brand cheap, tpo , Andrew, gold plated, Thank you for your teaching, Hug LU9EWO Jorge 73
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Page 520 Radio Armatures Hand book (by the A.R.R.L. staff) 1978. The original circuit used a MPF102 transistor but the 2N3819’s fine. I wound my coils (5 or six of them) on the plastic bodies of ¼” stereo jack plugs and I’ve been very happy with it. Fun to build and fun to use. The mini VNA dose a lot more but the transistor dip meter has been worth it’s weight in gold to me.
Good luck let me know how you get on. All the best ... Andy
Thank you for an awesome video!
Excellent! Thank you! I’m currently designing an HF dipole and have been stumped on what type of wire to use (copper V stainless). The skin-effect of stranded copper is far more favourable for a 75Ω feedline. Plus I can now work out the desired thickness...
Hi there, it’s due to self inductance, essentially an AC (or RF) current develops an opposing magnetic field within the conductor itself and that field has the effect of driving the current in the conductor away from the centre of the conductor and out towards the periphery of the conductor. The higher the frequency the more profound this effect becomes. I'm just making another video to go into it just a little bit more as it’s such an important topic.
Kind Regards ... Andy
Fascinating explanation of skin effect. All your videos are very informative.
Very informative and interesting. I really enjoy your videos. Thank you for sharing your experience and taking the time to make these videos.
Hi there, thanks for the feedback I appreciate it. It can take up almost a day to make a video depending on what graphics go into it but I really enjoy the process but it would be a waste of time if nobody wanted to watch them, so again thanks for the feedback.
Kind Regards ... Andy
Hi, it’s my pleasure. Glad you enjoyed it and thanks for the feedback.
Kind Regards ... Andy
Very interesting. Wondering if tarnish on the silver makes a difference.
Thanks Andy. Actually thinking about it that sounds spot on considering the 24SWG (0.56mm) I am using now gets a bit warm so I think using something like 22SWG (0.71) will take care of any skin effect related heating. (although I accept there will be other causes of losses).
By the way, do you know of any decent places online in the UK that sell magnet wire? as we all know maplin are daylight robbery with some of their prices!
Hey Andy,,, well once again some really great stuff. It's little details like this that help draw the bigger picture of understanding how all this works. Just a great job.
73
Carl
HELLO Andy
did you do a video on dip meter other than cleaning control
If you have time to do a demo on one I like your videos
I am in the process to purchase one
Thankyou
Dennis from Wis.
Great video - thanks. There is a high pitch noise in the audio - 6.63kHz and 7.17kHz. Goes away at 8:59, reappears 9:04.
Thanks Dennis, this is an important one and I'll be following it up soon with some more of the same. All the very best ... Andy
Hi Fred, couple of good questions there, neither of which I can give a satisfactory answer to. First I don’t know that Litz wire isn’t used much in the MHz region. It could be that a simple silver plated conductor can adequacy coupe with the currents involved. Regarding insulation I can only think that the dielectric would increase to inter-turn capacity but it’s not a problem I’ve come across. Let me know if you get a better answer.
Kind Regards ... Andy
Somebody in the old US Bureau of Standards (now NIST) did experiments and calcs that said that the cost/ loss/effectiveness point of Litz wire was about 2.8 Mhz. I have not seen his original research. But some modern experimenters have suggested that using Litz wire at higher freq will provide higher Q coils, well above the 2.8 Mhz region.
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Hi Dennis, I’ve made so many videos now I had to check to see if I did or not. I did a video on the ‘mini VNA’ antenna analyzer, I did two on that but that’s quite expensive given that I only use it once in a blue moon. 10 years ago I built a very successful single transistor dip meter that I’d recommend still works well, it uses a 2N3819 and a 50 micro amp meter and a two gang variable capacitor out of a radio. You can find the circuit on....
Hello Andy - Another excellent video - two questions for you, if you have the time
1) How come Litz wire is primarily used in the KHZ region (If coils and BCB loopsticks) but not found much in the MHZ region?
2) I have hearsd that a non-conductive coating can also affect the "Q" or the quality of a coil - is this also because of the "skin effect" ?
Another great video mate. Very informative. Thank you.
Hi Cass, thanks for the kind words. I'm glad the videos help you, but man its hours in the day that I need. But stay tuned as I hope to get some more videos out before too long.
All the very best ... Andy
At 50kHz the skin depth in copper at room temp is around 0.01118” (11.18 thuo) or 0.284mm so you could use a wire of twice that diameter (half the skin depth on one side and half on the other side) and you’d be getting good utilization out of the wire, you need to work out how many wires to carry the current. If it’s going to get hotter then the figure changes with the change in resistivity. I'm making another video on this and I'll put the formula at the end of it.
Kind Regards ... Andy
Hi Carl, this is an important issue, so much so I'm following it up with a similar video. If you can get to grips in understanding the mechanism of why inductance changes it helps it ‘demystify’ the notion of inductance changing with frequency.
Thanks for the feedback.
Kind Regards ... Andy
Great video Andy, I have been wondering about this sort of thing for a while now when designing a SMPS (only 50khz). How do you go about choosing a gauge of Litz wire for lower voltage high current switching circuits?
I enjoyed your video, I'll be watching more.
I would like to point out that it is not surface area that matters,
it is how much area the current flows in. Thinking about this,
caused me to do some calculations. Below I'll calculate
the current flow area for your Litz vs. solid.
If as you say the the skin depth at 100 MHz is .0008”
and the Litz wire is 0.00157” then current will flow through
the all of the area of the 0.00157” wire. The formula for area
is (3.14/4) D^2
So, area = 0.785 x (0.00157 x 0.00157) = 0.0000019349465sqin.
Multiply times 7 for each wire and we get 0.0000135446255sqin
Total area rounded is 0.0000135
In the solid 0.01” wire, current will only flow in 0.0008”
of the skin. I'll solve for that by subtracting the inner
(non current flow) area from the outer total area.
Outer diameter = 0.01”
Inner diameter = 0.01-0.0008 = 0.0092”
Total Outer Area= 0.785 x (0.01 x 0.01) = 0.0000785
Total Inner Area = 0.785 x (0.0092 x 0.0092) =0.0000664424
Subtract, 0.0000785 - 0.0000664424 = 0.0000120576
Skin Area = 0.0000120576
Total area rounded is 0.0000121sqin
Litz Area = 0.0000135 sq inches
Solid Area = 0.0000121 sq inches
So the math shows they are very close in there AC resistance at 100Mhz.
As you pointed out, the Litz is much smaller than the solid, and if you
found some Litz of equal diameter to the solid it would have more wires,
and it would also have lower AC resistance then the solid. Thus the usefulness
of Litz Wire.
I will add, everything I have read says Litz does help much past 3 MHz.
Thanks for the feedback, don’t worry about the possibility of confusion, I'm the better looking one.
All the best ... Andy
Man I'm sorry about that, I simply can’t hear it at all. Is it very bad? Funny that it comes and goes because the video was taken in a single take, all I did do was overdub one bit where I added an extra ‘Zero’ to one of the dimensions but I just voiced the four or five numbers.
Kind Regards... Andy.
Hi, let’s put it like this... it’s not on the top of my list of problems to resolve.
Thanks for the feedback on the video.
Kind Regards ... Andy
Hi there, sorry I thought I’d responded to you before now. See the next video (About Radio 56) and hopefully it’ll be made clear there, but essentially the alternating current in a conductor produces a magnetic effect that opposes the current flow (it gets in its own way) and that effect is strongest in the centre of the conductor.
Kind Regards ... Andy
Hi there, there real benefit of Litz wire comes at radio frequencies i.e. where the shallowness of the current is significant. I’ve never seen a radio frequency rotary generator but I guess you couldn’t make one; centrifugal force might be an issue. Let me know if you build one. Not sure what you mean by ‘power generators', because of the high I² R losses in the windings mains frequency ‘high power’ (power station) generators use liquid or gas cooled copper tubes for the windings.
Kind Regards
Andy, old (1918) transmission was by rotary generators (AC) at frequencies of 22khz or so. Limit was the centripetal force on the armature. Larger generators tended to explode when the G force became too much.
Does silver plating help a vertical antenna receive better or improve it at all ? For HF or 10 meter use.
Because skin effect is directly related to frequency, as freq. goes up skin depth gets smaller. but this relates to dc resistance vs the dc resistance (pure resistance) component of ac resistance. R + Z. The thing you want to increase in an antenna is Radiation resistance/ R (DC) ratio. RFradiation resistance is the energy lost in radiation, vs the energy lost in heating the wire.
Hi there, sorry I can’t help with suppliers if you don’t need too much maybe you can twist up your own if you’ve got any thinner wire?
Regards ... Andy.
Hi thanks for the feedback, I hope to bring you something interesting but it’s good to know it’s appreciated.
All the best ... Andy
gwojxm
awesome, well said.
I'm building a magloop antenna constructed from 4" wide copper ribbon so as to maximize surface effect. The ribbon arrived smooth and polished appearing from Georgia Copper but I anticipate that it would oxidize over time and develop the usual blue/ green oxidized somewhat rough feeling surface. Would you recommend that I apply lacquer or some other surface coating to prevent that ?
Hi John sorry for the late response but I get to reply to many comments. I can only guess that a poor surface will degrade the performance. Theory tells us this is true. I once repaired an 8MHz induction heater, we made a new work coil.Everything tested ok but it didn’t operate at all, it was for use in a plastic bonding application, it was only when the coil was polished that the efficiency was high enough for it to work. It was a really eye opener. Polishing the surface removes the hills and valleys at a microscopic level and effectively shortens the current path this reduces the resistance. I’d say it would be sensible to polish it every so often. I was going to suggest painting it and then taping it to protect the paint but you don’t want to trap moisture in that could alter things. Anyway good luck. .. Kind Regards . . . . Andy
AndyDaviesByTheSea thank you very much for the reply and the advice . Much appreciated
Hi John just one thing I was thinking about, if you use the loop outside how are you going to maintain stability? I don't know what size loop you are making but where I live if I put 4" wide strip outside it would flap about and that 'fluttering' would be a big problem. You'll find that tuning the loop is very twitchy. That is if the geometry of the copper work alters even a little bit it will detune the antenna. If you add too much support you could get into trouble with the high voltage because of bridging. I thin that even 3 or 4 mm thick strip (100mm wide) will flap around like you never expected. So unless you're going to use it indoors you might want to think about this and maybe see what other folk do.Good Luck!! let me know when you get it up and running, I'm off the air just now but I'd still like to see how you get on. 73's Andy
Hi, thank you.
Kind Regards ... Andy
Thanks for the feedback
Kind Regards ... Andy
If I build a long wire antenna using Litz wire, and assuming I can support it, so it doesn't break...will it work (better) than a single stranded long wire antenna..?
Hi there I really don’t think that you would perceive any noticeable
benefit from using Litz wire for a ham radio antenna. You could for instance
have your antenna gold or silver plated to reduce its resistance but it still
has to be correctly matched to the transmitter and I don’t think you would be
able to measure any practical benefit. I'm sure that getting the antenna at a
good height and pointing in the right direction would be far more rewarding. Kind Regards . . . Andy
@@AndyDaviesByTheSea Yep...that is kinda what I thought...so where are you in the world...im on Long Island NY..gonna snow here today..
I don’t envy you the snow. We were in NY one Valentine’s Day,
man that was the coldest I’ve ever been, we took a horse carriage ride around
the park, our teeth were chattering and we were shaking with cold. We were
warmer in Iceland in mid winter! Right now we’re in the Cardigan Bay area of
West Wales, (that’s in the United Kingdom) where it has been about 13 degrees C
all day (~55 F) and not too windy. All the best. . . Andy
Hi again, I hope what you looked up agrees with my explanation hi hi. It’s all done with jew jew beads and chicken feathers really but don’t let on as they're buying this stuff I come up with on RUclips.
All the best ... Andy.
Thanks...
Regards. . . Andy
GWØJXM
Hi there, thanks but you’re too kind.
Kind Regards ... Andy
would anyone be able to sell me litz in orange or yellow.44 or 46.175-220
ebay, may sellers
You talk about interesting things, but unfortunately I do not know your language.
...y los que no entendemos ese idioma nos fucking jodemos no?