EH Scott Radio Enthusiasts

The Fine Things are Always Hand Made

Special connector or link used by Scott?

I am still replacing the capacitors in my BOL Philharmonic (1939). Usually I make a hook on the end of the new capacitor and do likewise with the lead from the old one to tie them together before soldering. It's not the neatest method but it works for me. (I cover junctions with shrink tubing)

Today I pulled the original insulation off of the lead to a .05 mfd 600 volt capacitor and found what looked like a place where the lead had been extended by soldering two ends together to a what appears to be a tiny link. Is that what this is? Has anyone seen it before? Are these really neat items still available somewhere?

Please look at the rectangular area at the center of the lead in the photograph below.

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Looks like hooks in the wires to me.  The EH Scott Radio Laboratories did add extensions to component leads where needed and they did hook the ends of the wires to do so.  These extended leads were always covered with cambric insulation.

Norman

Norman: This lead was covered with the hard orange stuff you see to the left of it. Is that cambric? 

In this case I was able to put it back on the lead after shortening it a bit to make room for my hook.

Also, I just looked at the photo again and it looks like your are right. It does appear to be a very neat pair of hooks.

Thanks!

Norman S Braithwaite said:

 These extended leads were always covered with cambric insulation.

Norman

Ken:

Yes, the orange "spaghetti" insulation is cambric, a type of varnished cloth.  Scott also used larger diameter black cambric insulation over resistors passing through holes in the chassis.  Cambric insulation becomes brittle with age and is often difficult to salvage without damage.  But if warmed up with a heat gun, it softens and can be salvaged and re-installed (warm) with little difficulty.

Norman

My approach frequently, is to cut the original lead a half inch or more from the old solder connection. Scrape the remaining stub of the lead to clean it. Then shorten the lead if the new cap to the length needed, plus a another half inch or more. I then wrap the end of the new lead 2 or 3 turns around a very thin  object (wire or small jewelers screw driver) to make a small diameter coil. The inside diameter of the coil is just a bit larger than the stub wire. I slide the coil over the old lead stub and squeeze it with needle nose pliers tight to the old wire stub. Then solder it. Moderate size spaghetti should slip over it.

This leaves the old solder joint undisturbed - avoiding the risk of over heating an adjacent part like a resister, tube socket lug or delicate coil. This approach usually beats totally unsoldering a large junction of several parts and leads for sake of replacing one cap, especially if working space is tight. Also avoids the problem while heating up a large junction of having a large gob of hot solder getting away and creating a new problem.

This is also a strong way to add a length of wire to a cap when a really long lead is required.

David - That sounds like a great method for attaching new components! I will give it a try.
Regarding solder blobs, I usually cover nearby delicate items like coils with a small piece of sandpaper just in case something drops.
Thanks for the hint!

Ken, David,

I agree that the double hook method is acceptable for tight spaces and where you don't want to reheat a connection. If the old lead is scraped clean and the hook is pinched tight, a well sweated joint is stronger than the wire itself. There's usually plenty of old cap sleeve to cover neatly.

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