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Old 20th Aug 2014, 11:28 am   #1
Ian - G4JQT
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Default Frame Aerials

(Should this go to "General Vintage Radio" as it was originally about vintage radio aerials feeds, or is it "Homebrew" because it's partly DIY?)

For whoever wanted info on frame aerials:

MWDX circle have more aerial info than you'd ever need here with loop info at the end.

They also have loop info here with their MW source directory.

More here from 'frame aerials' Google images.

Tuned loops don't necessarily need any matching amp, but do need tuning! Un-tuned loops do need an amp.

Construction isn't critical (but don't use a metal frame!) and the size for MF the classic design is about 40 inch sides, with 7 to 8 turns (depending on tuning cap) and one coupling turn to the feeder to the set.

Very directional but not very portable!

Ian
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Old 20th Aug 2014, 3:18 pm   #2
paulsherwin
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Default Re: Frame aerials

You can also use a ferrite rod and coil if you don't have room for a frame, either amplified or unamplified.
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Old 20th Aug 2014, 3:47 pm   #3
Restoration73
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Default Re: Frame aerials

Another useful design
http://www.radionz.co.nz/listen/amhelp
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Old 21st Aug 2014, 12:13 am   #4
Biggles
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Default Re: Frame Aerials

I have had some success with relatively small ones measuring about eight by six inches attached on standoffs to the back of the set. I made a wooden frame a bit like a picture frame with small dowels in the corners, and simply wound approx twenty turns on for MW, measured the inductance and added or removed turns till I obtained the right value to resonate with the tuning cap. I found that they perform at least as well as a ferrite and are less prone to interference, but of course you can't adjust the inductance easily like you can with a ferrite rod, and they are prone to proximity effects if you mount them too close to the metal chassis.
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Old 21st Aug 2014, 7:39 am   #5
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Default Re: Frame Aerials

Ferrite rod coils tend to be fairly high Q and are resonated to get best sensitivity, which makes them narrowband, which is OK for one antenna per receiver but would limit the ability for the different sets in different rooms to be on different stations.

In a distribution system intended for general use, where the sets get moved around, I'd envisage a good broadband antenna with a distribution amp to a coax socket in each room. Then there would have to be a plugged in dummy antenna for sets with sockets, or a coupling loop like a mini frame antenna for sets with internal frames or ferrite rods.

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Old 29th Jan 2015, 1:28 pm   #6
Brian R Pateman
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Default Re: Frame Aerials

One post concerning a replacement frame aerial for a specific radio moved here; https://www.vintage-radio.net/forum/...d.php?t=113480
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