Surprise from a 1935 radio

[Radio Fixer]

This is an IF from an Integra French radio from 1935.

   

I have never seen the use of Ferrite pot core this early. I thought it was a 60’s – 70’s innovation, particularly by Mullards in Europe

Also there is some what looks like PVC insulated wire and it looks original ... some from the IF’s themselves

Luv these sets that throw up something from the norm.

Gary

[pwdrive]

Hi Gary, is it definately ferrite or iron powder, ferrite seems to be later developed by the japs and philips, a similar type of pot core construction is shown in the diagram in that pearmeabilty paper I put in the archives but obviousely the one illustrated in the paper is adjustable.
Interestingly I have a Hallicrafters SX 17 the manual states that the IF transformers are iron cored, these cores are not adjustable, aligning them is done by capacitor tuning, I have never taken one appart to see the type of iron core used inside them, the vintage is circa 1939, the xtal filter which is fed from one of these transformers pings up really well on CW and is bang on the nose resonance wise which is always a good indicator of a nice sharp IF stage.
All interesting stuff.

Lawrence.

[Radio Fixer]

Well I have no way of finding out what material it is so maybe I will just describe it as "pot core type construction". Buy it is unusual, so early ...

Gary

[pwdrive]

Hi Gary, I agree it is early, I tried to have a quick look in my SX17 as it has two dome nuts on the top of the IF screening can, I was hoping that undoing these would reveal all but it didn't, it would need the whole assy. to come out which I can't do at the moment.
I find all these early developments interesting, I guess the 30's was the heyday and a time when things really took off.

Lawrence.

[Radio Fixer]

The 30's is often called the "Golden Age of Radios" and it is to me Lawrence for restoration projects. Its here that the most variations are seen between manufacturing techniques, particularly if you work on foreign sets as well as the Brits.

G

[pwdrive]

I agree Gary, as you might be aware I work mainly on old comms receivers, that period was indeed the golden age and I find that there is still so much to learn, these old valve set designers were really on the ball in their day with some truly remarkable designs.
Keep up the good work.

Lawrence.