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 Post subject: WOOD RADIO LOOP ANTENNA
PostPosted: Oct Tue 27, 2020 1:52 am 
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Joined: Oct Tue 27, 2020 1:40 am
Posts: 2
Hi looking for information on this item..
what I am wondering about is age/model/did this fit into a wooden base or a radio.
Thanks ahead of time!
Dimensions
28" x 12" x 5"


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 Post subject: Re: WOOD RADIO LOOP ANTENNA
PostPosted: Oct Tue 27, 2020 2:28 am 
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Joined: Apr Sun 01, 2012 9:55 pm
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Location: Seattle, WA
Hi J, welcome to the forum!

It looks to me like the antenna for an RCA Radiola 28.
https://www.radiomuseum.org/r/rca_radiola_28.html

As you can see there, it's from the mid-1920s.

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 Post subject: Re: WOOD RADIO LOOP ANTENNA
PostPosted: Oct Tue 27, 2020 3:30 am 
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Joined: Oct Tue 27, 2020 1:40 am
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Oh I see, thanks for the help! Old one for sure..


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 Post subject: Re: WOOD RADIO LOOP ANTENNA
PostPosted: Oct Tue 27, 2020 3:30 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: S. Dartmouth MA 02748-1225 USA
FWIW: Radiola 25 uses 79 feet of wire has 13 turns and is spaced 3/8" apart with no center-tap. The metal contact blade in the center is not connected. The loops for the 25/28 are not interchangeable.

There is an ARF member who recently posted and is looking for a Radiola 25 antenna... chas

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 Post subject: Re: WOOD RADIO LOOP ANTENNA
PostPosted: Oct Tue 27, 2020 11:27 am 
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Joined: Jan Mon 18, 2010 2:13 am
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Location: Dayton Ohio
That is indeed a Radiola 28 antenna.

The Radiola 25 antenna does not have the 3rd contact. To my knowledge, this antenna would not fit into the electrical connector of the Radiola 25 unless the extra contact were to be removed.

-Steve

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 Post subject: Re: WOOD RADIO LOOP ANTENNA
PostPosted: Oct Tue 27, 2020 3:16 pm 
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Here is the full text of the notes I kept when I set about replicating Radiola 25/28 loop and wire. Seen side by side the 25 loop has rounded tips, a fillet, to the top and bottom flanges of the frame, the 28 loop the flange corners come to right angles. The center contact is included in the 25 antenna but it is not electrically connected, reference was made in Gernsback if one of the 25 loop contacts is ruined, salvage the center contact for connection. Therefore to confirm if, indeed the loop is for a 28 an ohmmeter can be used to prove the center connection.

Radiola 28 uses 85 feet of wire, has 14 turns, spaced 1/4" apart and is center tapped. Length or wire size is important as it affects the tuning drum alignment, improper length will narrow the effective tuning range either at one end of the drum or the other, despite adjusting the compensating trimmer. It is possible to go to #20 strand and be within tuning range.

FWIW: Radiola 25 uses 79 feet of wire has 13 turns and is spaced 3/8" apart with no center-tap.

Radiola loop wire is 64/36 B & S gauge equivalent to #18, bare copper, high strand, un-braided, .75/ft "Z" twist, 1st. cover SRC (rayon) or natural silk "S" twist, 2nd cover bronze rayon yarn, 18 carriers, braided, approx 100 denier (check den. to be sure). Finished wire is about .062" dia. 1/16". The loop wire is not a true braided litz with insulated strands but a high flex stranded wire that has a large surface area.

If someone was to seek a loop for these models, the buyer should insist the the center connect be checked or attempt to make a turns count from an image.

...chas

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 Post subject: Re: WOOD RADIO LOOP ANTENNA
PostPosted: Oct Tue 27, 2020 4:00 pm 
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Joined: Jan Mon 18, 2010 2:13 am
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Location: Dayton Ohio
Interesting.

My Radiola 25 did not have a provision for the 3rd contact.
I remember well as I found a 28 loop and it would not fit in.

I ended up selling the 25 after I found a 28 AC model with the 104 loudspeaker.

-Steve

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-Zenith
-Sparton
-Pre-War FM
Consoles and floor models, the bigger, the better!


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 Post subject: Re: WOOD RADIO LOOP ANTENNA
PostPosted: Oct Wed 28, 2020 12:27 am 
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Joined: Dec Sun 21, 2014 5:03 am
Posts: 415
Location: Traverse City, MI 49684
Chas wrote:
Here is the full text of the notes I kept when I set about replicating Radiola 25/28 loop and wire.
...chas


Can you include dimensions for the Radiola 28? I've got a radio but no antenna, and may be inclined to make one.

Chris Campbell


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 Post subject: Re: WOOD RADIO LOOP ANTENNA
PostPosted: Oct Wed 28, 2020 2:04 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 670
Location: Bristol TN 37620
Some great info there, Chas. Thanks for posting the specs.


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