Here is the continuing story and probably the last word on this scheme.

In part 2, I make the whole circuit work in a harmonious way and learn a bit more about how superhet circuits and valves work...back in 1950!

Mind you while scratching about making the 1.8Mc IF's work I would read papers and books like the Radiotron Designers Handbook.

There is a wide gap between the out and out theorists and the guys who actually wound the IF trannies!

Take the RDH for instance, one reads the chapter concerning IF coil design and we find a dozen pages of full on mathematics...equation after equation describing god knows what, but when you look for the final solution as to HOW many turns of WHAT size wire on HOW big a diameter and WHAT spacing on WHAT type of former...…..nothing!

After looking at lots of commercial IF coils you get the idea of what was practical at the time and it was lot of fun getting there.

There are also a few brave souls who have described on line their experiments at producing 455KC IFs as nobody seems to be making new ones!

I hope the experiments help others to get a feeling for the superhet principle in practice.

Fred.

Superhet Wide Band Tuner - Part 2

Document uploaded.

A rivetting read Fred!

Hope you are well. Do you know yet when the op is?

Hi Ian, yes had heart surgery on Tuesday, its all over except for the crying!!!!
This little lot was a thing called PVA (pulmonary vein ablation) you can google that one, but I can confirm it SMARTS!
It may not be a chest opener like bypass/grafts (had that), they only drill little holes in your hide to get inside but hoo boy....

Sorry Brad a bit off topic there!

I find the subject of how IF transformers work is fascinating, when I stop crying and clutching my chest I might have a further tinker with those 1.8Mc units and investigate the coupling aspect, re under / over / whatever.

Thanks, Fred.

No probs. I work at a hospital that runs four cardiac catheter labs so it's all strangely familiar even though I've never been on the table.