Here I go again making something up out of junk bits.
I'll do this build in 3 parts.
In this part I look at the 247 output valve, output transformer and sound reproducer.
On looking up the specs for the 247 valve I found contradiction about when this was introduced.
Some sources say 1936 to 1938 others a bit sooner but I think much sooner.

My valve is a balloon envelope with the 5 pin base marked e RCA 4
Radiotron

This looks to me like a 1920's to 1930 style valve. When I look at the specs of the valve it looks like a design stepping stone between the triode/screen grid and beam tetrode designs being a 3 grid straight power pentode in the 40 series of output valves.
I don't recall seeing many of these in radios even early 1930's sets had 2A5's or 42's and earlier sets had A409's or the like.
Possibly the 47 was a dead end with no where near the power of say a 2A3 and not used much.
I simply could not luck upon a history of RCA valves so could not pinpoint when this tube may have been made.
Somebody may be able to enlighten me.

Reinartz 3 Valve Radio Part 1

Fred.

The RCA Radiotron Radio Tube Manual Technical Series No. R-10 of 1932 shows a balloon shape 47 valve.

http://www.tubebooks.org/tubedata/R10.pdf

My hard copies of the Technical Series No. RC-11 (1933), RC-12 (1934) & RC-13 (1937) all show the 47 in the later ST-16 package. The 1933 edition has a circuit for a typical superheterodyne radio using a pair of 47's in push-pull.

If you trawl around the net you may find earlier editions of the RCA Radio Tube Manuals that can be downloaded. At that, I'm guessing the 47 or 247 dates from around 1930.

Here's pictures of various type 47:

https://tubeworldexpress.com/collections/power-tubes/47.

It also has the blue PZ which they say is an equivalent type.

I have 1 PZ and a few type 47 in my collection.

File uploaded.

Thanks guys I did more reading about RCA and Cunningham and understand a bit more about valves around the 1930 mark. My 47 is shown as you say in the RC-10 (1932) manual as the balloon shape and then RC-12(1934) as the ST shape. From the "antiqueradios.com" site the statement: " the UX247 released June 1931" is made. My valve has a very faint '47' marking on the balloon glass and RCA RADIOTRON on the base. I guess that puts it between 1932 and 1934. I also saw mentions of the PZ and the P-704 as being very similar other valve manufactuers products. I guess they were all following the same design path.
I was also dead wrong about the 47 being a minority use valve, I did not understand the American market and how many receivers used the 47 as single and push pull configurations. Two 47's in P-P gave a huge output and removed most of the problems with hum ripple bypassing with the then tiny capacitors available and reduced the size of the output tranny having lost the single end DC offset in the core. I'm still learning!
Whatever my 47 is a real survivor and I suspect in pretty good condition possibly having been discarded as faulty early on in its life due to the arc over between the wires in the base.
I have progressed the audio section to a useable design using the 47 and a 1D4 to drive it. The 1D4 is an example of using the wrong valve for a purpose but it was an interesting exercise to make it work as a voltage driver and not an output valve. With a gain of more than 40 it works out ok in this mode and gave a sensitivity of about 1/2 volt input for full output.

FredL.

Reinartz 3 Valve Radio Part 2

File uploaded.

Hullo All
I have continued the Reinartz set design and made the front end work after a lot of mucking about. That makes the whole thing work well enough to lock the design at that point and leave the final build and cabinet for a part 4. At least now I know a bit more about old school triodes and pentodes and how they react at RF with coils. The possible combinations of circuit arrangements with different coil types and valves are endless and at a point I start to lose interest and want to do something else.
Not shown at all in these notes is the mathematics behind a lot of the action of the valves and circuits. I just prefer to show the results of experimenting in simple terms rather than going deeper and using mathematical jargon. Anyway half the time I have no idea what maths guys are talking about. Once you get past the simple solvable equations and obvious vector notation expression I am truly lost!

Cheers, Fred Lever.

Reinartz 3 Valve Radio Part 3