Recepteur Type RI 221

[pwdrive]

That's a really fantastic set, Lawrence and I can appreciate the efforts which are going into your reverse engineering! It is the sort of receiver used in embassies the world over in the 1920s. I note that in the RF stages, the range switching is so arranged that there is never a shorted winding damping the others unlike the simple LW-SW switching of that era.
It reminds me of an ST&C Supersonic Heterodyne type 44004 from 1926 which I have. The set was specifically intended for FO type duties and was available with or without cabinet. I will upload the details to Radiomuseum in the near future as they have now corrected their entry for the Western Electric version of the set, the 4004, which was listed as a 44004. I have the curved labels which are positioned above each of the controls - but I can't find them at the moment   . The hole in the panel is for a two range meter which measures the two HT+ feeds. The valve are mostly WECO triodes in series/parallel on 4V LT.

Brian, my apologies for not replying in detail to your above post earlier, the reason was that what you suggested in it reflected a hunch I had with this receiver, I had a hunch it was something official to do with a government/ military.

The first task for me was to try and establish what this unit was first of all, that's why the decision to reverse engineer the circuit was taken.

The conclusion of that was that it is radio receiver for sure and an unusual one at that.

Having done the above the next task was to give the cabinet a close examination for any clues, the cabinet has badly deteriorated in places, however I wanted to establish if the cabinet was original to the receiver or the cabinet was a later addition eg: a cut down /modified bread bin done by a home DIY'er, the cabinet is roll top of the type that would be found on a writing desk or bread bin.

I've finished examining the cabinet, with an interesting result.


The cabinet itself and the roller shutter is constructed from mahogany or a very similar type of hardwood, the backing cloth for the slats has long since detached, all the cloth is still there but generally rotten, it looks like calico.

The cabinet base has molded edges as does the cabinet top, the slats slide in a rebate, pinned to the inside edge of the rebate near the rear edge of the cabinet are three leaves of thin varnished veneer, the three leaves have not been glued together and are fixed inside the rebate close to their edges by some thin pins, the bottom of the leaves sit flush on the cabinet base, the tops of the leaves finish just below the end of the radius of the rebates near the back edges of the cabinet sides, the leave that's nearest the cabinet back is chamfered along its top edge in favour of the slats, the jointing method for the cabinet base and sides is by butt joints, pins and glue, however the top is screwed on using eight screws.

When the receiver is in the cabinet there is plenty of clearance between the back of the receiver and the three leaves of thin veneer, access to the gaps between the veneer leaves can be gained by unscrewing the top and removing it.

That suggests to me at the moment that the gaps were there to store a document or two in, a secret compartment maybe, I might be wrong on this and just dreaming so what I'll do is take some photo's and upload to the forum so folks can see what's what and offer their views.

The cabinet is an exact fit to the receiver, I don't think it's a DIY home brew job, There's no evidence of the cabinet sides and the ends of the slats being hacked with a hand saw by a DIY'er, the backing cloth for the slats finishes approx 6 mm from either end of the slats as one would expect, that glue line is visible because the cloth has long since become detached, the glue line does not extend beyond the edges of the cloth.

I have made some more observations about the bias battery connections and another connection but I'll leave that for another post, I also made a mistake reading the value of the filament rheostat, it's 8 ohms not 6 ohms as I first concluded,   The cabinet pictures will be uploaded today, Mrs has bought me a Petzl ....ideal for this type of work.

Lawrence.

[pwdrive]

Cabinet pics as promised:

Top view of the cabinet base:    

A view of the underneath of the base:    

Outside view of the slats:    

The pieces of backing cloth:    

Top and underside of top rear panel including its fixing screws:        

Top view of the three veneers mentioned in an earlier post, the top edges of the veneers are chamfered in favour of the slats:    

Inside view of the left hand side panel showing the innermost veneer towards the rear of the LH cabinet side where the veneers go into the rebate:    

Bottom view of the three veneers showing them fixed in the rebate (RH side) there is no glue on the faces of these veneers, the faces are varnished, they are only fixed at the edges, they are fixed at that point by pins:    

The rearmost veneer, the fixing pins at the edges had rusted through that veneer which enabled me to remove it completely after this picture was taken:     

Lawrence.

[pwdrive]

Part section view showing the veneer panel locations and general arrangements shown in pics in last post:

   

Lawrence.

[AlanBeckett]

Just been back to the Top to look at the original Pictures of the Front Panel and the Internals. It's all a lot clearer now. There's certainly lots of scope for 'Twiddling'.

Alan

[pwdrive]

I was about to hit the sack late last night...then I got to wondering...a niggling feeling, nowt for it, I had to get the other two veneers out to have a look, suprisingly they came out quite easy as the fixing pins were well rusted through, the thinnest veneer came out first, it's the same thickness as the first one I took out a couple of days ago (the rear one).

That revealed the middle veneer, about 25mm in from the right hand side there was what appeared to be a full length split running from top to bottom (grain orientated vertically) the other two veneers had the grain orientated horizontally.

So.....Originally it must have been plywood, I had a close look at the split and it turned out that it wasn't a split but a core join, all this might tie up with the bias battery, there's no front panel terminals for one, when I first aquired the receiver to look at there were four wires coming out of some holes in the cabinet base, they can be seen in the first set of pics I posted in this thread, three of them would make sense, two for the GB -ve for the two audio stages and the other for GB +ve, so what about the fourth wire....well that goes to the HT side of the 1st interstage transformer, it's the only wire that's connected to it, if you look at the 1st pic in the 3rd set of pics I posted you can see a wire with termination loop left unconnected on the end of it, it's wrapped round another wire and is located south east of the 1st interstage transformer in the pic, the other end of the wire with the loop is connected to the HT +ve terminal on the front panel, I'm 100% sure that the looped end was originally connected to the HT +ve side of the 1st interstage transformer.

So what does all this mean? Well at the moment I think that originally the receiver had a GB battery fitted internally (absence of GB terminals on front panel)
The plywood towards the rear of the cabinet was there to stop the roll top from fouling up on the GB battery and it's connecting wires (can't think of any other reason for it being there)
The holes in the base of the cabinet that the wires feed through look like later additions, they look rough eg suffered from breakthrough when being drilled, three of the wires coming out of the holes were for an external GB battery, the fourth wire coming out of one of the holes was for an external HT battery to supply the 1st audio amp for whatever reason, maybe when the Mullard series of valves were fitted.

I'm also thinking bright emitter valves (French TM) were originally fitted.

What do folks think?

Lawrence.

[AlanBeckett]

Why 4 Volts and a Rheostat and not just a 2 Volt Accumulator?
Was that normal?
I've seen Sets with that set up - Rheostat in the Filament Connection - but with just an ordinary 2 Volt Accumulator.
With 4 Volts available and 2 Volt Valves I should think there's every chance of blowing them up. Or were they 4 Volt Valves?

Alan

[pwdrive]

Not sure Alan, not really done much with 1920's valves, if they were bright emitters that were fitted it would give the option of reducing the filament voltage, I gather that increased the life expectancy of the bright emitter types, from all accounts they had a short life at full whack, I read somewhere that some bright emitters needed more than 2 volts, 3 volts and over being common, that's assuming this receiver had bright emitters, I've no sure way of knowing at the moment, alternatively it might have been fitted with 4 volt dull emitters and the rheostat was used to crank the gain down a bit with the RF amp being a tuned grid, tuned anode circuit, need to find out more if I can to fill in the gaps.

Lawrence.

[AlanBeckett]

Bearing in mind the state of some of the Timber it's a miracle it's not just a pile of bits.
What are you thinking of doing about it?

Alan

[pwdrive]

Alan, Re the timber: the cabinets top panel is ok, that would go again, the rear and the side panels have rotted out on all the bottom edges, the base is the real basket case a decent chunk of it has simply rotted away, that's the bit in the front LH corner, there are strands of rot fungus on the base and the base feels unusually light, the plywood panel inside the cabinet just off the back is also shot, the roll top slats are in the main ok and would go again.

So... What would I do with the cabinet, I would like to think that I could cut all the rot out, give it a good dose of stuff then graft some new bits in, that would provide continuity for its history.....that's the dreamy stuff, in reality it would be simpler to make a new cabinet to the original specifications.

The story so far with receiver: A woman I know was basically being evicted, I was helping to clear one of the sheds out, most of the stuff was being burnt on a bonfire, the receiver nearly ended up on it, I spotted the tops of the valves just in time, I offered to store it in our house to dry out and to see If I could find out anything about it.

At the moment I don't know what she would want done with it.

Lawrence.

[AlanBeckett]

I suspect that in the right Auction, and with a decent presentation, it could be worth serious Money.

Alan