The AM Forum

Hi to all:
I just read in an old 73 magazine article about the link antenna coupler.  The author made reference to "Pee Wee" coil clips for making tap connections on the tank coil.  Has anyone seen these coil clips and is there a source for them?  I don't like the alligator stile clip because is offers minimum contact with the coil.  I need a spring loaded type of coil clip that wraps around the body of the tank wire or tubing.
73,
Chuck  

Well, the 'Pee-Wee' IS an alligator clip: :-\

http://parts.digikey.com/1/parts/389264-clip-pee-wee-steel-5a-bu-45.html

They were very popular for that purpose.

73DG

Wow, I never heard of clips called PEE WEE??

This is the only Pee Wee that I know.

i never considered those alligator clips, what i call an alligator clip are these, like what are used on the end of a set of clip leads.

(http://www.asia.ru/images/target/photo/50877931/Alligator_Clips.jpg)

i have a few smaller ones too that are very hard to get open, unless you use a pair of needlenosed pliers.

I remember seeing a picture of a spring loaded coil clip that actually wrapped around the wire or tubing of the coil.  Does anyone know of these?
Chuck

Pee wee clips are totally different from the pictures here.  They were small clips that had a screw to tighten it against the winding of a close spaced coil.  Millen, I believe, made them.

the only thing i can think of that would be like that is a fahnestock clip, but they're a type of early connector.

I Googled Millen coil clips but came up zip.  Anyone else have a source or picture of these coils.
Thanks guys.
Chuck

here are some knock-offs:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220734809467&ssPageName=STRK:MEWAX:IT

To me, when you say Pee Wee Clip, this is what I think of.

I think that is what he is talking about.  I ran across a source for them a couple of months ago when I was looking for the kind that used to be made by EF Johnson for clipping onto edge-wound coils. Didn't make note, since that wasn't the kind of coil clip I was looking for.  Do a Google search for "coil clip".

I had a few of those in my junk box.  They worked FB OM for the air wound coil stock I use in my BC1-T that replaces the original crappy grid coil wound on bakelite. With the new coil, I get 30% more grid drive for the same driver plate current.

The two sizes of copper tubing coil I am using are 1/8 inch (.125) and 1/4 inch (.250) outer diameter.  The clips in the photos are to small.  I have some of them.  Dose anyone remember those spring loaded dual "S" shaped type of clips that wrapped around the conductor?  Or, are there any other suggestions for a high quality coil clip for the sizes I need?
Thank you.
Chuck

A friend of mine built and sold bug catcher mobile antennas and he used small alligator clips.  He would use a small file to remove the teeth then needle nose pliers to form the flat surface so that it made maximum contact with the coil surface.

If you are building a high power tuner, you need as much surface contact as possible to carry the current.  To improve efficiency you really should wrap the wire around the turn of the coil then solder.

Those are B&W clips. 3942 for up to #12, 3943 for up to #8 and 3944 for edgewound.

I believe it was B&W who developed the airwound inductors in the mid 30's.

Carl

There's another type that are a small, flat, criss-cross arrangement. Along the lines of an alligator clip but without teeth and no spring or pivot - much simpler. I have some on an old 1930s balanced feed tuner with a plug-in coil at top and the clips attached to wires. Just clip them onto the coil then adjust the air variables.

They sound like what you might be describing, Chuck. My laptop with the camera software is in the shop or I'd snap a couple shots. These things are very small and simple, but adjust to a larger diameter when you squeeze them open.

Looks like this (http://www.bwantennas.com/coils/coilclip.htm) is all they have now.

Just like our dwindling bio-diversity, as time goes on, the variety of available manufactured products to select from, for about any purpose, is steadily decreasing.  >:(

Everyone thank you for all your help.  However, none of these coil clips are what I saw.  The B&W coil clips now available are to small.  Todd if you have time could you take a snap shot of the coil you mentioned. 
Thank you.
Chuck

In the old days the hams would have made their own. Pretty simple part to form.

Seems like B$W creatively extended the 3942 to #10. I used to sell a package of 25 for $10.50....looks to be simple enough for a small garage shop to come up with a product.

Carl

What would be the steps in tooling to make a quality coil tap for 1/8, 1/4 or 3/8 tubing?
Chuck

Using thin aluminum strips, it should be easy enough to bend them to suit, Chuck. You could even use something like a finish nail of similar diameter as a form.

The ones I have are flat and just pinch the coil. The tuner doesn't look like it was designed for huge power, though. It will probably be a few days, but I'll see if I can get a couple pics with a cellphone and post them. The other pc with the camera software won't be ready for another week or so.

You would need something like phosphor bronze or a springy stiff alloy of copper. Aluminium is notoriously non-springy and subject to fatigue; I have heard it said that even in solid form, the metal still retains some characteristics of the molten state and tends to gradually flow away from pressure points.  That is why the stuff is such a disaster when used for internal house wiring; the metal flows away from clamped connectors, eventually resulting loose connections that form arcs and cause fires... also the reason why power line noise from "hot clamps" has become such a common nuisance, now that the electric power industry has turned away from copper power line conductors in order to "save money".

E F Johnson once made the familiar clips that slide onto edgewound coil stock. Using some sheet copper I had on hand that happened to be about the same thickness as what they used to make those commercial clips, I homebrewed a few exact copies of the EFJ clips about 30 years ago and they are still in use.  They work fine, even though the pure copper was never quite as springy as the nickel-plated alloy that EFJ used. Clips for round wire coil stock should be easy to make if one could find some sheet metal stock of the same alloy as used to commercially manufacture the clips. The nickel plating retards corrosion, but pure copper probably makes just as good electrical contact, particularly if lacquer or other substance is sprayed over the permanent connections to keep oxygen away once the spot is located on the coils for the taps.

Unfortunately, I no longer have any of that copper stock to make more clips.

 Todd, You are very close to any easy home brew clip. Copper or brass stock would work FB and a nice finishing touch with electroless nickel plate (easily done at home with any one of many kits)The closer you place the clamp screw to the tapped coil, the more secure the connection. Yes, you could use spring bronze but not really a must have as copper is readily work hardened as is brass.

Hmmm, finally a use for those damn SB-220 shorting bars that I always remove and toss in a box.

Would you have any specific recommendation for "work-hardening" a piece of copper strip, while preserving its shape and leaving its surface smoothness intact? By definition, "work hardening" involves deforming the metal, something like banging the piece with a hammer until it is slightly flattened, or hammering a straight piece to form a bend. Stretching a piece of soft-drawn copper wire is another example that comes to mind and I have actually done that, but it would be very difficult to stretch a short piece of 1/2" copper strip. You want the part of the clip that contacts the wire or flat ribbon on the coil to be as smooth and flat as possible to assure maximum surface contact.

I have observed that heating a piece of copper until it is red-hot, and then letting it cool back to ambient temperature, leaves it very soft and pliable. Bending the softened and cooled piece a time or two immediately re-stiffens it, but I am not sure how the end result compares to its original state. I have never noticed any hardening effect from simply bending a piece of cold copper. If anything, it would seem to soften it, and bending more than just a few times would result in metal fatigue and it would break.

I am not sure what metal the commercially manufactured clips like the EF Johnson ones are made of, brass, bronze or copper, since I have never had enough lying around that I would be willing to damage one by filing, bending or cutting on it to test its characteristics.

 Work hardening for the most part with copper is a continual process. It happens as the metal is "moved".The forming actions involved by making the clip will by nature harden the copper. Every time the metal is bent it hardens. Working copper with highly polished hammers on polished surfaces will harden the metal while preserving the surface finish. Alternately , the surface may be refinished to the desired lustre after the forming is completed.

I wish someone would re-produce these:

If you are looking for a clip to use on a coil,  you might consider the coil clips that the Buddipole folks use on their coils for their portable antennas. They are sort of a J-hook that goes around the far side of the conductor, and are pulled up snug by screwing down a plastic thumb wheel over them to pull them up against the coil. They are designed to mate up to a small banana plug to allow several to be preset over a coil and the banana plug moved between them for band changing.

http://www.buddipole.com/coilclips.html

Those might work on the VFO coil ;)

I made some coil clips similar to the Buddiepole clips.  This style of clip will bends the copper tubing when you tighten down the bolt.
I will keep brain storming here. 
Chuck 

Those are exactly the ones I used.  You saved me the trouble of taking a snapshot of mine and uploading them. Mine were made by EF Johnson, but in about 1980 I made several more by exactly copying the design, using some copper stock I had on hand. Some of the commercial ones and homebrew ones were mixed together on the same antenna tuner, and when I re-built the tuners last year I had a hard time telling them apart.

The top example is easy enough. It's identical to those used on knife switches. A plate slid through the bottom opening and a bolt connected both to the base. The second looks like a purpose-made version of the first. I've seen these on larger coils.

The bottom one is identical to the ones EF Johnson made, and I have seen them in two or more sizes. It is also identical to the homebrew ones I replicated. A small square spacer of the same material as the clip is placed in the opening where the screw goes through, to keep the hairpin bend from collapsing when the screw is tightened. The spacer has to be about the same thickness as the edgewound coil stock in order to get a good grip on the coil while maintaining the maximum surface contact and not deforming the bend thus altering the parallel angle the "fingers" make with the flat coil stock. Like knife switch contacts, these clips are "springy". My homebrew ones were made using regular copper and turned out to be less springy, but they still make good electrical contact with the coil when the screw is tightened.

Never use a steel screw or nut for these; always use brass hardware.

Edgewound coil stock (also manufactured by EFJ) comes in different thicknesses, so I assume they custom made different size clips to fit.

The two depicted above, and two more, came riding on an edge-wound coil I picked up at a hamfest. Try as I might, I have not been able to find any more of these.

Sadly I just let a bunch of the top style go, though they were likely too big for most coil applications. They came off some large slate power panels with copper knife switches and fuse clips out of a 1920s office building rehab. Had several panels that were damaged, so I gave them to a fellow who smashed them up for the copper rather than haul them south. Did salvage 4 complete panels, though I'm not sure what I'll do with them beyond hanging them on the wall as Industrial Art.

Keep your eyes peeled at hamfests and flea markets for old knife switches. The smaller 2-3 pole types use these clips for the lever leads to clip into. Most often copper, sometimes steel. They're also used for the center pin on big jugs like 204A, 851, 849 etc.

Hey Chuck I decided to go thru my store of parts and take a gander at my "gator" clips drawer..I think I got what ur looking for..says Pee Wee clip pat pend on one side and Weller Electrical Co on the other..also has No 45 on the clip end..kinda looks like a clothespin thingy but as you squeeze it down the clip end opens from approx 1/8" to just over 1/4"..the inside part is a spring between the two paddles..at the other end is a small machine bolt and also a crimp type attachment point so I guess you could attach wire both ways..if this is wicked important to ya I can mail it to you gratis..just send ur mailing address to me via my e-mail found here in my bio..I won't shed a tear even though it is my only relic from way back          73 de DAVE