Permeability-tuned Crystal Radio - UK Vintage Radio Repair and Restoration Discussion Forum

vu2nan-nandu · 18th Oct 2015, 2:31 pm

Here's an update.

It's uses an empty lip salve stick as a tuning mechanism.

Read more.....

http://nandustips.blogspot.in/2015/0...tal-radio.html

Regards,

Nandu.

18th Oct 2015, 7:31 pm

I had an old crystal radio that used a variometer (variable inductor), much the same idea as yours but before the days of ferrite. Good to keep the old ideas going with a modern twist (pun intended!).

vu2nan-nandu · 19th Oct 2015, 7:07 am

Hi Merlin,

Yes, it's fun to re-create and understand established concepts!

Many thanks.

Regards,

Nandu.

Neil Purling · 19th Nov 2015, 8:56 am

Can you do anything with a re-cycled and re-wound IF transformer?

Peter.N. · 19th Nov 2015, 12:50 pm

I also have used variometers. You can wind a coil on almost any insulating material, a toilet roll centre used to be favourite in the '40/'50s

Peter

vu2nan-nandu · 19th Nov 2015, 2:21 pm

Quote:

Originally Posted by Neil Purling

Can you do anything with a re-cycled and re-wound IF transformer?

Hi Neil,

A 455 KHz IF transformer from a vacuum tube set would be quite suitable. However the capacitor would need replacement to cover the required frequencies.

Regards,

Nandu.

Restoration73 · 19th Nov 2015, 3:01 pm

Variable inductors with adjustable cores were used as convergence controls in older
colour tv sets, these can be used if they have a value around 500uH.

kalee20 · 19th Nov 2015, 3:15 pm

Variometers were used, and probably were cheaper than variable capacitors!

However, they are not permeability tuned as there's no moving core - the windings are shifted so that the various sections are more or less coupled to each other. It alters the inductance as a whole, but strictly I suppose it's OT for this thread!

18th Oct 2015, 2:31 pm	#1
vu2nan-nandu Pentode Join Date: Jul 2014 Location: Bangalore, India Posts: 132	Permeability-tuned Crystal Radio Here's an update. It's uses an empty lip salve stick as a tuning mechanism. Read more..... http://nandustips.blogspot.in/2015/0...tal-radio.html Regards, Nandu. Attached Thumbnails

18th Oct 2015, 7:31 pm	#2
Guest Guest Posts: n/a	Re: Permeability-tuned Crystal Radio I had an old crystal radio that used a variometer (variable inductor), much the same idea as yours but before the days of ferrite. Good to keep the old ideas going with a modern twist (pun intended!).

19th Oct 2015, 7:07 am	#3
vu2nan-nandu Pentode Join Date: Jul 2014 Location: Bangalore, India Posts: 132	Re: Permeability-tuned Crystal Radio Hi Merlin, Yes, it's fun to re-create and understand established concepts! Many thanks. Regards, Nandu.

19th Nov 2015, 8:56 am	#4
Neil Purling Nonode Join Date: Jul 2005 Location: Hull, East Yorkshire, UK. Posts: 2,087	Re: Permeability-tuned Crystal Radio Can you do anything with a re-cycled and re-wound IF transformer?

19th Nov 2015, 12:50 pm	#5
Peter.N. Dekatron Join Date: Jul 2008 Location: Charmouth, Dorset, UK. Posts: 3,601	Re: Permeability-tuned Crystal Radio I also have used variometers. You can wind a coil on almost any insulating material, a toilet roll centre used to be favourite in the '40/'50s Peter

19th Nov 2015, 3:01 pm	#7
Restoration73 Nonode Join Date: Jun 2013 Location: Surbiton, SW London, UK. Posts: 2,801	Re: Permeability-tuned Crystal Radio Variable inductors with adjustable cores were used as convergence controls in older colour tv sets, these can be used if they have a value around 500uH.

19th Nov 2015, 3:15 pm	#8
kalee20 Dekatron Join Date: Feb 2007 Location: Lynton, N. Devon, UK. Posts: 7,082	Re: Permeability-tuned Crystal Radio Variometers were used, and probably were cheaper than variable capacitors! However, they are not permeability tuned as there's no moving core - the windings are shifted so that the various sections are more or less coupled to each other. It alters the inductance as a whole, but strictly I suppose it's OT for this thread!