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1940 Style Loop Antenna
#1

Can anyone describe the particulars, sufficient for me to build a copy, of a 1940's Philco loop antenna that was narrow enough to allow me to rotate it, within the cabinet of my 41-295. I haven't seen one, but I understand that it was a "muffler" looking design and would provide a degree of selective tuning that is not possible with my original, wider unit.
#2

The original was a square with 4 copper loops separated by wooden guides. It only rotated a little bit inside the cabinet. The wire appears to be 10 gauge solid. I might have an extra if your interested. Let me know and I will look.
Glenn

Happily back in Illinois..not.
#3

Glen,

Thanks for your quick response, and your generous offer to possibly make your antenna available to me. The 41-295 came with a square loop made from two fairly large diameter wires, but it isn't able to rotate through more that ten or fifteen degrees within the cabinet. My understanding is that an earlier 1940 model had a loop that was constructed such that it was more rectangular and could be rotated to a much greater degree. I've seen the loop described as looking like a "muffler". Zenith had an early "Wave Magnet" that looks very much like what I have imagined this early Philco loop to be. The Zenith was also enclosed in what looks to be a cardboard box. Unfortunately, the box conceals the details of it's construction. If, in fact, Philco had a similarly constructed loop, I would like to find out more about the details, so I could attempt to duplicate it's construction. It would be helpful if I knew the exact dimensions and wire gauge used. Not sure if the actual wire composition, or type of material, would be that critical. Any thoughts?

Henry
#4

Henry,
I have seen that style, but don't have any info regarding that. I think RCA used a similar one as well. I'm wondering what I can do to increase the signal strength if this existing antenna. I saw the posting for the longwire adapter, but not really sure I want a 100 foot wire hanging from the house. There must be a better solution out there. Any Ideas?

Glenn

Happily back in Illinois..not.
#5

The 1940 loop antenna will not work in a 1941 Philco. The design and construction is completely different. If you want your radio to work correctly you have to use the antenna designed for it.

Henry, you have an alternative...you can construct a smaller (narrower) loop, about the same size as the "muffler" you want. Then you can rotate it more. You'll have to readjust the antenna trimmers in the radio once done, but that should be it. Use four turns of heavy gauge wire, tapped at two turns. Keep the turns insulated from each other. Copper wire is much softer than the alloy originally used in these loops, by the way.

You could use insulated, solid wire if you don't care about originality; a narrower loop as I described won't be "original" anyway. Just come up with some sort of frame that will hold the wire in place, and fit into the holes above and below so that you can easily install and rotate your new, narrow loop.

Paul Pinyot's website shows the internal construction of a 40-190 "muffler" antenna. Looking at it, you will see how different it is from the 1941 loop.

http://www.ppinyot.com/zenith/rotating_antenna.htm
Glenn - there are desktop loop antennas, amplified antennas, etc., out there on the market; but I don't believe you can improve upon a good outdoor longwire for best reception.

--
Ron Ramirez
Ferdinand IN
#6

Ron,
I thought that would be the case, but I would need to fashion the 3 pin connector mentioned in another post for my 41-300. Don't know if I'm up for that...maybe once I finish the 39-55 and need one anyway. Icon_smile

Happily back in Illinois..not.
#7

You hit another "Home Run", Ron. I'll see what I can do with Paul's information. I did hook up a loaner C.Crane Twin Coil Ferrite AM Antenna, and I was pretty impressive. A little pricey, but it added a whole new dimension to both the selectivity and sensitivity of the receiver. I will say that the original antenna, that came with both the 41-295 and the 41-300 I have, works just fine during the day, but is entirely different once the sun goes down. That's where the C.Crane unit came in real handy.

Glenn, I also have a 39-55 that I have been working on, from time to time. I haven't yet figured out a solution for the missing spring in the wireless controller. Found a clock spring that will probably work, but will require a bit of milling to proper width, and I then have to find a way to attach it to the unit. That end of the original looks like it was spot welded to the winding sprocket. Pretty much stopped working on it when the 41-295 and 41-300 popped up.

Thanks for your help. Going to go hang out on my sister's cattle ranch over the holidays. You guys have a great holiday, also.

Henry
#8

Henry,
I hear that my 41-300 is awesome during the day, at dusk it gets turned off. The same goes for the 42-340 I rehabbed for my MIL. I need to check out the twin coil you mentioned. I recapped all the electrostatics and the run cap on my 55 yesterday and tried it and lo and behold it fired right up, Icon_biggrin . I'm waiting on a 78 tube and am fashioning a power supply for the mystery control so I can test it before moving on to replacing the rest of the caps. I don't think this was used much back in the day, all but one of the resistors is within 10%. The caps look good, but I would hate to finish the cabinet then need to take the chassis back out because I didn't replace them.
Have a merry Christmas.
Glenn

Happily back in Illinois..not.
#9

hyounce Wrote:I'll see what I can do with Paul's information.

Henry, did you see the first sentence in my last post? A stock 1940 loop will not work on a 1941 Philco, and vice versa. Now if you make a modified loop as I described, with four turns of heavy gauge wire, tapped at two turns, you should be OK.

--
Ron Ramirez
Ferdinand IN
#10

Ron,
Yes, I will give that a try. Sorry I didn't get right back to you, but things have been pretty hectic around here. Recovered a complete stereo that I originally purchased in Hong Kong back in 1969, and am now in the process of bringing all the pieces back to life. Unfortunately, my nephew reduced everything to rubble, and that sometimes brutal master "Nostalgia" has me hooked on putting a lot of time into, once again, repairing what used to be.

The specific equipment was pretty "high-end", for the time, as I went into the Sony dealer and ordered their very best they had to offer. Was surprised, last week to see the FM tuner I purchased then with a starting bid of $400+ dollars. Turns out that it's now a rare piece, and still very competitive among the "high performance" receivers in the FM world. The only problem is that it's not working, and the parts are hard to find. Does that situation seem "familiar" to anyone?

Henry




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