Passive loop with vintage radios

[agardiner]

Hi all,

I am thinking of getting a Tecsun AN-200 passive loop antenna to play with.

Has anyone tried one of these or similar with a vintage radio? I suspect they work best with sets using ferrite rod antennas, but what about looping a few turns of a wire antenna on one to couple? Any thoughts?

Cheers,

Adrian.

but what about looping a few turns of a wire antenna on one to couple?

That will work, how well is the question. For a lot less money you could build a "wellgood" https://www.george-smart.co.uk/projects/wellgood_loop/ copy of the Wellbroook active loop and get better performance.

[sabaman]

Hi Adrian,

I have one of these loop antennas. In my opinion they work well with transistor radios with ferrite antennas, often producing a very useful improvement. Good for ground wave DXing if a long wire antenna is impractical. They just look a little ungainly when positioned next to a portable! Mine has a 3.5mm output jack, so you may find you can connect the loop antenna directly to the antenna socket of the radio, though I've not tried this myself. Not sure how effective winding the radio's wire antenna around the loop would be. Be aware that the tunable loop will indeed increase the signal strength of the desired station but it also brings up the noise to an extent. MW only of course.

Cheers,

Sabaman.

[G6Tanuki]

In times-past to improve reception of a MW portable with ferrite-rod antenna I made one of the classic 'frame' antennas [a wooden X with arms about a foot long, about 20 turns of wire looped round fishtail-spreaders on the end of the X and tuned with a 365pF variable capacitor]. The transistor-radio mounted on a shelf fixed to the centre of the X. This gave a noticeable improvement in reception of Luxembourg 208M during the early evening.

[Stuart R]

Adrian,

I bought one a few years ago as a means of using-up a birthday gift of an on-line voucher. Definitely more fun than spending it on a T-shirt or groceries.

Much improvement to listening when placing it alongside AC/DC radios with internally wound antennas such as my DAC90A and Defiant (Champion Meteor/Comet).

But, I've also tried using a 3-pole Mini Jack plug to connect it to other sets with Aerial and Earth sockets, such as my Wartime Civilian set and Ekco A22. Despite trying various connection combinations, the loop is always out-performed by a 2m length of wire dangling around the curtain rail!

As Merlin Maxwell says, try building Dr George Smart's Loop, much more useful.

https://www.vintage-radio.net/forum/...d.php?t=169949

One day, Merlin's going to show us a picture of his finished loop with the very useful rotator (!)

Kind Regards,

SR

[Junk Box Nick]

I have an AN200. It works well placed alongside ferrite rod transistor sets and in some cases pulls a barely detectable signal up to listenable quality. It’s very compact compared to a home constructed loop – mine is sitting on the window ledge next to a small portable. One of the best accessories I own.

[G6Tanuki]

For radios with a ferret-rod antenna, in times-past there was the "Dewtron Wave-Trap" which was an additional ferrite-rod antenna with associated single-transistor amplifier, feeding adown a length of coax to a coupling coil.

https://www.vintage-radio.net/forum/...d.php?t=144226

[agardiner]

Really appreciate all the comments so far. I think I might take the plunge and get one to play with, and if it sparks further interest then proceed to construct the larger loop.

Although I dabble with SW and mainly listen to FM, MW still holds magic to me and pulling in distant stations is great fun. Plus there are more things to try and pull in now that BBC local radio has all but gone from the band.

[FERNSEH]

Still a lot of interest in medium waveband DX reception. Have received on many occasions east coast American stations through the tuneable loop aerial.

DFWB.

[majoconz]

By 'passive' do you mean 'unamplified' or 'untuned'. Tuned loops are easy to make, perform really well - but can hardly be call 'unobtrusive'. Here's one that I made in an effort to tune down to the NDB band - 200 to 400kHz - but did not achieve it - even with a 3 gang capacitor all in parallel. Each loop arm is a metre long. The inner two turns are a low impedance coupling loop to a receiver - all the other turns can be connected in various ratios to tune the required frequency. Works brilliantly on the AM MW band with very deep nulls.

[Julesomega]

The AN-200 is tuned and unamplified. The output is high impedance intended for use with the Degen 1103 antenna input which is high impedance and will not work for 50ohm inputs

[Julesomega]

Originally Posted by majoconz

Here's one that I made in an effort to tune down to the NDB band - 200 to 400kHz - but did not achieve it - even with a 3 gang capacitor all in parallel. Each loop arm is a metre long

You need more turns and several nF switched in parallel with the variable to get down to LF. I made one with 40t close-wound and I forget how many nF to get down to 73kHz

Here is a wonderful loop aerial from Tim Hunkins "Secret life of the radio" https://www.youtube.com/watch?v=LMxate9gegg 10 minutes in.

[agardiner]

Originally Posted by merlinmaxwell

Here is a wonderful loop aerial from Tim Hunkins "Secret life of the radio" https://www.youtube.com/watch?v=LMxate9gegg 10 minutes in.

Thanks for sharing that. Happy memories of this series and recently rewatched them all as Tim has remastered them.

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Thanks again everyone for the comments and suggestions.

BR,

Adrian.