Loop Aerial

[Murphyv310]

Hi.
An interesting thing that can be worth a try, is to use a 1 metre tuned 6 turn loop with single turn secondary is with a RF low to high impedance matching transformer on the single turn.
From the high impedance secondary add an OA91 and set of high impedance phones, one instant selective crystal set that can happily pull in reasonable strength stations.
This works far better than adding a detector and phones to the tuned 6 turns, the single turn will struggle to give 200mv signal to detect. The addition of the transformer will give higher voltage to detect, go too high and the frame will be loaded excessively and become less selective and actually give less audio.

[Radio Fixer]

Thanks for the replies Gents.

I will have a better play when time  and the mind allows and report back.  At the moment there is much going on: decorating hall, landing and stairs and making good after new doors fitted.  Had to take off some stops and fit new then burn off, prime and paint.  Also I have another radio nearly completed and an article almost done ... plus and most important of all hospital visits for my wife.

Getting interested         Where do you get the ferrite rings Trevor?

Gary

[Murphyv310]

Thanks for the replies Gents.

I will have a better play when time  and the mind allows and report back.  At the moment there is much going on: decorating hall, landing and stairs and making good after new doors fitted.  Had to take off some stops and fit new then burn off, prime and paint.  Also I have another radio nearly completed and an article almost done ... plus and most important of all hospital visits for my wife.

Getting interested         Where do you get the ferrite rings Trevor?

Gary

Hi Gary.
Oh well that's a question! I've had these for many a long year, try Maplin or any of the Radio hobby dealers, they are common enough and should be easy to find.
They are really useful for many things.
Have fun

[Radio Fixer]

Any characteristics to take into account and what is the most useful diameter?

Ta Gary

[pwdrive]

http://toroids.info/

http://www.amidoncorp.com/specs/

Other sites/info around.

EDIT: That T50-2 toriod that shows up in the first link isn't my selection it just came up that way on the site.

Lawrence.

[Radio Fixer]

Ordered 20 for £6 so well stocked now. Its the ferrite used in the amp circuit found by Trevor.

http://www.ebay.co.uk/itm/111898975475

Gary

[Murphyv310]

Ordered 20 for £6 so well stocked now.  Its the ferrite used in the amp circuit found by Trevor.

http://www.ebay.co.uk/itm/111898975475

Gary

Well done Gary.
I'm sure you will notice the difference once you make it up. I did find that experimentation was the best way, it's time consuming though and fiddly winding a lot of turns round them, definitely worth it though.

I'm going to put on a new thread about my frame aerial crystal set! It's great fun and surprisingly good. Not sure though if the missus would be too happy with in the bedroom at night if I wanted to listen to the radio  

[Radio Fixer]

Tried it with a transformer from China and it made no difference ... think it was worse but I will give it another go.



How can it match when the aerial input is so indeterminate for a domestic set?

But thanks Gary

The item you have is to match a long wire which is high impedance to a radio that's low impedance. Basically a reverse of what you are trying to achieve. Try connecting it in reverse, hopefully it'll work.

Why is it so obvious when you know.  What it is stands out like a sore thumb now.  Should always ask on here first.  I haven't tried it in reverse but will do when I start experimenting.

Gary

[Murphyv310]

Tried it with a transformer from China and it made no difference ... think it was worse but I will give it another go.



How can it match when the aerial input is so indeterminate for a domestic set?

But thanks Gary

The item you have is to match a long wire which is high impedance to a radio that's low impedance. Basically a reverse of what you are trying to achieve. Try connecting it in reverse, hopefully it'll work.

Why is it so obvious when you know.  What it is stands out like a sore thumb now.  Should always ask on here first.  I haven't tried it in reverse but will do when I start experimenting.

Gary

Hi Gary.
There is a very good chance it will work a treat!
Good Luck

[AlanBeckett]

One hopes that it's a Passive Linear Bi-lateral Network so it damn well should.

Alan