diy IF transformers: first attempt.

[Amie]

I like that... ....gives me another option.

Cheers

Adrian

Thanks!  You're welcome Adrian. Just be aware that these are just experiments, though I have hacked one into the 1st IF of an old Sky Captain chassis and it works acceptably as is.

I don't see any reason why the idea wouldn't transfer to higher frequencies for your TV IF's. Moulded chokes are available to suit the values needed.

The components used here are made by Epcos.

Impressive - particularly the symmetry above and below the centre frequency.

Within the bounds of Amīcalabs flaky test equipment, yes! However I did find that placing the chokes axially, that good linearity disappeared like the morning mist, but I don't know why

Isolation between primary and secondary should be absolutely above suspicion with this technique.

Absolutely. One experiment that worked very well was back to back transistor style IF's, I haven't completely exhausted that idea, but as one wise sage pointed out to me, the enamel in those miniature cans coils are good for 50volts at best.

One thing occurs to me - and you are ahead of me on this particular topic - if a screening can is wrapped around, I bet it will affect both coupling and tuning a lot less if the coils are arranged longitudinally rather than transverse. Happy to be proven wrong, though...

The prototypes as pictured were that physical arrangement for ease of assembly, and adjustment. Once made like that I was surprised how easily they coupled, and yes any screening will affect it.

They are 20mm square, and the screening can may need to be twice that, Another option is mount the chokes out of plane with each other so they can be adjusted variometer fashion, and therefore be closer.

I will experiment further if, as I suspect you are correct, and it is badly affected by the screening....

WTS.

Thanks.
Amie.