Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5

Short wire on tuning capacitor on 41-250 and 41-280
#1

On both of my 1941 Philcos there is a short stub of stiff, insulated wire soldered at one end to a terminal on the top of the variable capacitor. The other end is just cut off.

On one of the radios the wire is about 2.5 inch long, and is soldered to the teminal on the capacitor on the left. It curves through the terminal on the other variable cap (kind of an "S" shape) but doesn't make electrical contact with that terminal because of the insulation.

On the other radio, the wire is about 1.5 inch and runs horizontally but does not touch the other terminal. There are traces of solder on the terminal that doesn't have the wire on it.

I don't see anything on the schematic. Anyone have any idea what that wire is for or what it may have been connected to at one time?

John Honeycutt
#2

Think these are so called gimmick capacitors you are describing. They only connect at one end and are only a few picofarads of capacitance. Zenith did this on some of their radios. A small amount of the oscillator signal is coupled back to the RF input lead of the mixer stage. It was negative feedback that was important at shortwave frequencies.

Richard
#3

Richard is correct in that this is known as a "gimmick" capacitor.

Replace the insulation on that wire, and then put it back the same way it was. Otherwise the radio will not function properly. If you do not replace that rubber insulation, it will crumble and short over time.

--
Ron Ramirez
Ferdinand IN
#4

I have wondered what a "gimmick" was. I ran across the term in a book on radio repair, but it wasn't explained.

One last question. Was the gimmick trimmed and routed for each radio or was it just cut to a predetermined length and routed according to a print? The reason I ask is that I already replaced them both with new wire, cut to length and routed as in the 41-250.

In the 41-280, the wire was quite a bit shorter and just hanging into space, and I thought the other routing was neater. I no longer have that wire to measure the length. Is there a procedure to trim and route it so that it works properly?

By the way, I have two 46-350 portables, and each one has a short length of wire sticking up from the volume control and not connected to anything on one end. Is that the same thing?

Thanks.

John Honeycutt
#5

Hi John

In essence, a "gimmick" is a very small capacitance not in the usual capacitor package, but instead, a couple insulated wires twisted together or, in this case, a wire twisted around - but not making electrical contact with - a metal terminal.

In the case of the 41-250, 41-255, 41-280, et al., the wire should run through the terminal of the variable capacitor and then folded back. If it is not routed in this fashion, the radio will not work properly. In your 41-280 that has the wire just hanging in space, that radio will not work right until you run the wire through the terminal and fold it back (if you have not done that already).

The 46-350 wires you describe is something entirely different. I do not have the service info for the 46-350 handy, but it seems to me that was done as a test point?

--
Ron Ramirez
Ferdinand IN




Users browsing this thread: 2 Guest(s)
[-]
Recent Posts
Rusty Tuning Condenser
Hello Rob. I've also heard of soaking the tuning cap in automatic transmission fluid. This was an old trick we used to...GarySP — 06:14 PM
Rusty Tuning Condenser
Gary, I once had a tuning cap that had a thick coat of kitchen grease and grime. So I had heard about brake cleaner bei...RodB — 06:03 PM
Rusty Tuning Condenser
I've put tuning caps with mica removed and vanes wide open in the dishwasher and ran through a cycle. When the dishwash...GarySP — 05:42 PM
Rusty Tuning Condenser
I do not think Philco 91 used pot metal for the tuning cap. Also, in 1930-s pot metal did not have iron, being mostly co...morzh — 04:56 PM
38-10T chassis Restoration begins
Rich do you dunk the whole razor in there with it turned on to get a good mix? :lol:dconant — 04:48 PM
Rusty Tuning Condenser
David, RodB says to watch out for pot metal as it might dissolve in vinegar. I think there might be some in there. I thi...dconant — 04:40 PM
Rusty Tuning Condenser
Give the tuner a good wash in Dawn and hot water. Then set tuner in a plastic container and cover with vinegar let soak ...David — 12:53 PM
Rusty Tuning Condenser
If you have rust between the vanes, I wonder how you get the NJ in between, and how you then wipe it off.morzh — 12:02 PM
Philco 60 Squealing
If the noise is still there, the OPT might just be OK. Or so we hope.morzh — 12:01 PM
Philco 60 Squealing
You would probably be replacing the OPT.RodB — 10:54 AM

[-]
Who's Online
There are currently 3303 online users. [Complete List]
» 1 Member(s) | 3302 Guest(s)
Avatar

>