Ok, I had a good read of John Moyles article on the original "L-G" RH April 1940.
Now, being aware of some subtleties of Superhets I am actually intrigued by the original circuit.
So intrigued I am going to build a replica, that is using both the CIRCUIT and the LAYOUT.

I want to explore just how well the layout worked and why as the authors seemed to be quite surprised how well it performed.
The RH crew had made quite few superhet radio circuits with various layouts for both MW and SW use so were well versed in the practical sense, in "design".
I am so aware now of what positive feedback ( regeneration) can do to an IF stage gain.
So long as this is controlled by limiting or neutralising the improvement can be a gain of many times a straight stage.

The IF stage in this set looks like it has positive feedback of RF from the detector to the cathode.
Having seen how much RF can exist on a supposedly "bypassed" to RF wire I am suspicious.
The set may have accidental regeneration due to the components and layout used.

They did not have the facility or did not show what each stage gain actually was.
I can make up an identical chassis and use 1940's style parts and "have a dekko" at how it worked.

Little General 1940 Replica - Part 1
Little General 1940 Replica - Part 2
Little General 1940 Replica - Part 3
Little General 1940 Replica - Part 4

Fred.

You would be surprised on examination just how many sets were deliberately designed to encourage some regeneration, giving them a bit of a free boost.

The most incredible set I have ever worked on was a factory special based on AWA "R-301". I ended up reverse engineering it as is had a 6A6 PP output and bias changes through out, from the production model.

Sensitivity was unbelievable and at full volume no signal, that's what you heard...nothing!

Marc

Part 1 uploaded.

I often learn something new here Fred, and this article is no exception.

I have seen radio receiver front end valve cathodes coupled in this manor so many times but never gave the implications a second thought until now.

Looking at the circuit with a fresh outlook I see a potential variable frequency oscillator waiting for the right conditions to morph itself into a transmitter.

Great tuition, many thanks.

I must say this is true inspiration!

Thanks Carl I'm still learning all the time!

I have the chassis up and running now and digging into the design a bit.
I'll post a part 2 when I have some sort of conclusion

Fred.

I ran out of time on this project at a point where the set works but not well.
I'll send a part 2 to Brad to add to part 1 in post #1.
I'll pick up the project in the future.
Fred.

Part 2 uploaded.

Amazing how you can just make up something out of spare bits, wire it up, and it works.

Hi Rob, yeh its probably understanding in a deeper way why and how something should work and then fixing the bits that fail as you go.
I could not have done this project 20 years ago, or maybe I could have. But there would have been a lot of floundering on the way and possibly stopped dead at a point where I did not understand how some part works until I worked out how!.

Thats experience, learning, and a lot of confidence (bluff) all mixed together.
There is a psych thing here, somehow no matter what field I was working in I have always been confident of success.
One just plods on solves or bypasses problems and gets a result.

Its cool and sometimes thinking sideways in problem solving.
A lot must go back to an apprenticeship straight out of school where we manufactured electrical equipment from the raw materials.
Cut the metal, wound the coils, welded the frames, drilled the holes, machined the bearings, made the contacts, poured the castings, made the moulds, plated the metal....you name it.

Thats how you learn CAN-DO.
I made equipment with no drawings and just a verbal description of what the thing had to do and where it fitted..
This is well before computers and programs.
We made stuff and once proved the drawing office then drew it up!
A different way of engineering in a different world.

Fred.

Just wondering, you mentioned you needed a longwire to be able to pick up the metropolitan stations. Does that apply to 2RPH?

Rob, very funny!
2RPH can be received through a badly tuned toaster where I am.
Even with a dead valve or open circuit coil I can depend on 2RPH to come through loud and clear!
There is a signal path through the ground, the signal level from 2RPH is higher via a ground lead than an aerial.
That I discovered 20 years ago when I accidently picked up the earth stake wire instead of the aerial when I was fixing some deaf set.
2RPH came blasting through and confused the hell out of me.
Must have something to do with underground water tables and how they have their mast configured.
You can pick up 2RPH with a diode connected to an amplifier input, no tuning needed!
Fred.

Is it possible to power a light or LED soley from the power of 2RPH ? Or maybe even a low-power appliance? A quick experiment should be able to prove the point one way or the other.

On the to do list!
Most likely will work with a big tuned coil at 2RPH frequency and a LED.
Fred.

I have completed the part 3 to this thrilling series.
In this I complete the set to working stage investigate how it works and where the design came from.
Part 4 to come will cover the dial and cabinet.
Will send the part 3 story to Brad to pin to the lead page in this thread.

Cheers, Fred.