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Pinched/Crimped Antenna Coupler Tank Coil




 
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Author Topic: Pinched/Crimped Antenna Coupler Tank Coil  (Read 9509 times)
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aa5wg
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« on: June 24, 2010, 10:53:43 AM »

Hi to all:

This topic deals with my home brew link coupler. 

After winding the tank coil around 4 support bars I did not want the coil to spring loose.  I slipped each end of the coil (made from 1/4 inch copper tubing) through a 1/4 inch hole drilled in the support bars and crimped the tubing one inch from its end on the opposite side of the support bar.  The crimp is preventig the copper tube from slipping back throught the hole.   The coils is mechanically sound and is not slipping or springing loose.

I tested the coupler on 160 - 10 meters and it works well with no probllems, 100 watts. 

Do you think this 1/8 inch wide pinched/crimped section of tubing, that is one inch from the ends of coil,  will cause any RF related problems at full leagal limit power, 160 - 10 meters?

Thank you.

73,
Chuck - AA5WG
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w3jn
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« Reply #1 on: June 24, 2010, 11:01:43 AM »

No.
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aa5wg
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« Reply #2 on: June 24, 2010, 12:59:12 PM »

W3JN and all:

Thank you for your input.

Anyone else have some input?

73,
Chuck
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w3jn
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« Reply #3 on: June 24, 2010, 01:32:40 PM »

Doubt there's anything else to say.  No reason a little crimp is going to affect anything.  However you're free to solicit additional answers if you don't believe me  Grin
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aa5wg
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« Reply #4 on: June 24, 2010, 02:36:10 PM »

Hi Johny:
Thank you for your fast information.  I did not want to offend you.  I never tried crimping tubing with high power HF RF.
Again, thank you for your help.
Chuck
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AB2EZ
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"Season's Greetings" looks okay to me...


« Reply #5 on: June 24, 2010, 03:11:00 PM »

Adding to what JN is saying...

The tubing tapers down at the crimp, tapers back up after the crimp, and then connects to whatever conductor it is connected to next. The critical issue is: how long (physically) is the distance between the beginning of the taper down, and the end of the taper up compared to a wavelength at the operating frequency. In this case, thias distance is a tiny fraction of a wavelenth (a centimeter or so v. tens of meters). Therefore, there is very little phase shift between the beginning of the crimp and the end of the crimp. As a result, there is a tiny reflection that is produced when an rf wave (travelling toward the crimp) enters the crimp zone, and a tiny reflection produced when that rf wave exits the crimp zone... but nothing more. It is very much the same effect as would be produced by a connector, inserted where the crimp is. Since the surface area of the crimped region is about the same as the surface area of the tubing itself... there should be no problem with localized heating.

Best regards
Stu
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Stewart ("Stu") Personick. Pictured: (from The New Yorker) "Season's Greetings" looks OK to me. Let's run it by the legal department
aa5wg
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« Reply #6 on: June 24, 2010, 07:22:24 PM »

Thank you Johny and Stu.
Chuck
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WBear2GCR
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« Reply #7 on: June 25, 2010, 01:37:11 AM »

These guys are misleading you!! Yes. True.

This is known as "electron pinch".
It can result in electron "pinch off" if the crimp is very sharp...

What happens at an atomic level is somewhat unclear yet, but it seems that the electrons collide, like cars all heading for the same ramp at the same time. Some are pushed off the "road" and so they are emitted or else burn up and heat is generated.

Now one good solution for this is to reduce the friction in the crimp area(s).

One reference from back before WWII mirrors what I have heard from old-timers. Use some extra antenna wax in the area, don't scrimp on it, and after it sets properly, then buff and buff. This helps the electron flow... so this is the best way to go...


Hope this helps out...

                                 _-_-bear

Oh, if you are low on antenna wax or need some in a pinch, ask around I am sure someone can send you some...

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_-_- bear WB2GCR                   http://www.bearlabs.com
W2WDX
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« Reply #8 on: June 25, 2010, 11:17:13 AM »

Some clarification needed bear ...

I had heard that when using the wax on coils that the rotation of the buffing is critical. Some say that the rotation should be done in a CCW direction and others say CW. Additionally there is a school of thought that says the rubbing should be done juxtaposed to the pitch of the coil. In other words if it is a right pitch you should rub it going to left, and the opposite if it is left pitched.

Also, I have heard the rubbing should be done in the direction of the flow in one direction only, to reinforce the  alignment of electrons in the direction of current flow. I have also heard that using a specially prepared piece of Myrtlewood underneath the rag helps align the electrons better due to amore rigid rubbing action.

So my question is ... how does a bear rub his coil?  Tongue

John
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Ralph W3GL
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« Reply #9 on: June 25, 2010, 01:07:45 PM »





     Aw, comon fellows, don't confuse the guy with facts !

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73,  Ralph  W3GL 

"Just because the microphone in front of you amplifies your voice around the world is no reason to think we have any more wisdom than we had when our voices could reach from one end of the bar to the other"     Ed Morrow
k4kyv
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« Reply #10 on: June 25, 2010, 10:14:19 PM »

Try coating your antenna with D-X grease. That keeps the air away from the wire, so that way you'll know your copper is oxygen-free.

http://zippy.cso.uiuc.edu/~roma/roadmaps/images/NA/D/D-X1954.jpg
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Don, K4KYV                                       AMI#5
Licensed since 1959 and not happy to be back on AM...    Never got off AM in the first place.

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« Reply #11 on: June 26, 2010, 09:40:47 PM »

I thought the buffing was to be done following the right hand rule. That must be why the marzal vanes in the deplenerator have been warping. This has been plagueing me for years. Thanks!
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w3jn
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« Reply #12 on: June 27, 2010, 12:21:31 AM »

All kidding aside, Chuck, how's the tuner working?  Did you do another "K1JJ" style?

How about a picture or two of your project?
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aa5wg
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« Reply #13 on: June 27, 2010, 07:43:36 AM »

Hi Guys:
The 80 - 10 meter link/tank coil is going to be taken apart.  I ran out of antenna wax. 

All kinding aside, I am going to rebuild the link/tank coil(s) for 160 meters.  How do you add pictures to this post?  Do I copy and paste from desktop?

Any other helpful hints?
73,
Chuck
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w3jn
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« Reply #14 on: June 27, 2010, 10:03:23 AM »

Two ways you can do it.  In the "reply" box, see the "Attach:".  Click the "browse" button and you can attach a file. 

Or, you can upload the picture to a service like photobucket.   Photobucket will then provide you a link with IMG tags on either side.  Just copy and paste that link and you're good to go.
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W2PFY
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« Reply #15 on: June 27, 2010, 01:21:20 PM »

Well, it is that time of year again. Time to go out on the roof and wax the antennas and rotate the coax. The snow from last weekend has melted and it looks like we are done with that for the year.

I think I will try the Signal Master Wax this year. I had been using Larsen's Premier Antenna wax the last few seasons and, while it has worked well, it just doesn't seem to improve the signals as much as I would like. I noticed the signal strength from the dis-cone is much lower this Spring than last, I suspect the wax has lost its sheen. I suspect that it is time to rotate the coax as well.

Has anyone been able to compare the different brands of antenna wax and can recommend one over the other?

Thanks!
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k4kyv
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Don
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« Reply #16 on: June 27, 2010, 01:44:26 PM »

Back to the subject to crimping the coil.  I don't think the crimp would have any effect at all.  At rf, the current flows mostly at the surface of the wire, due to the skin effect.  That's why copper tubing works just as well as solid wire.  What is important is the surface area of a given segment of the wire.  It doesn't matter whether it is flattened, remains a circle or is made rectangular in shape; the total surface area is still the same.  Some coils are wound with copper ribbon instead of round tubular copper.  Edge-wound ribbon is physically more compact and probably has a slightly higher Q.  Edge-wound copper ribbon can be fabricated by winding a coil out of tubing and then carefully flattening each turn using whatever tool one might be able to come up with that would do the job.
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Don, K4KYV                                       AMI#5
Licensed since 1959 and not happy to be back on AM...    Never got off AM in the first place.

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aa5wg
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« Reply #17 on: June 27, 2010, 02:08:45 PM »

K4KYV, W2PFY, W3JN and all:
Thank you for all the help.
I will get to work on this new coil.
73,
Chuck
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WBear2GCR
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« Reply #18 on: June 28, 2010, 01:12:02 PM »


What - I didn't help???   Roll Eyes Roll Eyes
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W2PFY
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« Reply #19 on: June 28, 2010, 03:28:54 PM »

Quote
and all
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aa5wg
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« Reply #20 on: July 04, 2010, 11:22:46 PM »

WBear2GCR and all:
Thank you.  The work on the 160 meter link/tank coil is still in progress. 
73,
Chuck - AA5WG
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WBear2GCR
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Brrrr- it's cold in the shack! Fire up the BIG RIG


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« Reply #21 on: July 05, 2010, 04:26:52 PM »


Gorsh - he thanksed mee... Cheesy

            _-_-bear
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« Reply #22 on: July 05, 2010, 07:17:09 PM »

" Gorsh - he thanksed mee... Cheesy

            _-_-bear   "

He didn't thank me.... ..


klc
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What? Me worry?
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