1928 Set

I think the RF amplifier valve is supposed to poke through the hole in the screen. Yours may be a more modern model though.

[David Simpson]

Thanks Guys for the kind words & comments.
In the initial thread post back on the 22nd Nov, and again on the 24th - showing the poor old set after I'd brought it home - that indeed the RF valve was horizontal through the hole in the screen. As it is in S-T's old pictures.
But, placing it vertical left a bit of usable extra space in the Det/AF area. Thus was able to screw everything down without supporting components in thin air, so to speak. Yes, I know it was common practice with S-T, Peto-Scott, and others back in that era, but to me its unsafe & looks silly.
Incidentally, I replaced the original worm infested/rotten pine base-board with a sheet of lovely flat ex.grade 10mm veneered plywood covered with a sheet of lovely old paxolin. Looks great, but originally thought of using a sheet of Ebonite. Sadly, it wasn't until I was half-way through the project, that I was told of a good source of genuine Ebonite sheeting, any thickness, from the Far East. Gordon Simpson - another BVWS member told me.( Jesus - what a fantastic collection of 1920's sets he has. A dedicated & skilled restorer).
That Revophone 1Valve/Xtal Set awaits more TLC.

Regards, David

[PJL]

That looks excellent and very original.

Whatever you might think of Scott-Taggart, his writing style is particularly arrogant with minimal technical content, the designs do work very well. I think the ST400 is from about 1930 but the ST300 is earlier and there were instructions on how to upgrade your ST300.

I also have an ST300 that has been converted to Mains again by closely following instructions published by ST. The mounting board had been reduced to dust by woodworm and as it has no case I started to re-build both radio and PSU onto a wood frame that would fit an earlier mahogany BBC marked case from an unidentifiable manufacturer. Time I finished it before I forget where I put the parts.

PS: Not so sure about the vertical socket for the tetrode. The idea is the grid connection sits on the AE side of the shield and the anode structure is on the opposite side. You would probably get more controllable regeneration if you put it back as original. My ST400 has a purpose designed socket for horizontal mounting.

[David Simpson]

Thanks PJL. Right enough, these old sets seemed to have attracted their fair share of woodworm to their bases.
Re the SG valve, you could well be right about isolating the anode circuitry from the grid's. I'm afraid I'm a mere student when it comes to ancient TRF circuitry, having only restored one other - a 1927 3 valve GECoPhone. Just goes to show that one is never too old to learn from others. Mind you, some of the pictures I've seen of old TRF's circuitry are such a higgledy piggledy of angled wiring going hither & thither between valves & components. Probably, interaction between anode & grid circuitry must have needed a lot of trial & error by kit constructors.
What I did initially, a few weeks ago, was to firstly wire up just the RF section & power it up with the necessary HT's & LT's. Then just connected my headphones via a wee diode to the o/p stator of V1's anode diff. condenser. A basic one valver, so to speak. C1 & C2 and T1's diddy variometer provided adequate basic tuning & stations could be heard(just about), and no feedback or oscillation. So just plodded on with the rest of the wiring. Running all the wiring at right angles, and tinning every screw terminal connection certainly used up a few man-hours.

Regards, David

[Phil G4SPZ]

David, well done, you've made a lovely job of that set.

The oldest set I've ever worked on was a 1929 Marconiphone 55 TRF portable. Progress was very rapid in those days; barely five years later, the commercial TRF had all but disappeared. I think Scott-Taggart receivers were aimed at the home constructor, for whom the TRF offered the challenge and excitement of extracting the last ounce of gain out of a fairly simple circuit by means of the multitude of adjustments. Upgrading to later circuits and the ability to re-use existing components were popular features of S-T's designs.

This thread has prompted me to dust off my 1933 copy of JS-T's 'Manual of Modern Radio' which is actually quite comprehensive.