Sorry for not replying more quickly. I've had the back off it again
It has been a bit berzerk here lately: We've been doing a new release, plus all my voluntary stuff.
I replaced a lot of old capacitors that looked a bit heat-worn and aged. The whole right channel of the stereo FM facility was not working, and it was down to dry joints, probably exacerbated by the train ride from Luxembourg to Brussels. The resistors are all still the originals. I am a bit reluctant to replace them, as I like the equipment to be as original as can be.
The EM series valve (magic eye) is a bit of a special one
Because it was tuned into a SW station at the moment I took the photo, the extra bit at the side is not lit, but it can, though. It has an extra anode to display when FM stereo tuning is correct, so it not an EM84; is a EMM803. A very lovely valve. My old Telefunkens use EM84s and I have five, but I can't find a replacement EMM803, so that's a bit of a worry.
The output stage amplifier valves to me repersent the pinnacle of thermionics.
ECLL801 is the code, so if you are not familiar with the Philips/Mallard style code, here we go.
E = heater voltage of 6.3vdc, in parallel
C = there is a triode in there.
L = there is a pentode in there.
L = there is another pentode!!
So, we can make a lovely push/pull output stage amp with no real effort. The only other time I came across such a neat and effortless design was the 6809 CPU.
Now: one Saturday, I went up to Eindhoven where next to the Philips works there exists a bit of a bourse of old valves. To my delight, I was able to buy four ECLL801s, never used, and they cost only EUR40.
The other valves are plain enough. ECC85, ECH81, EAF801, ECC83
The power supply is 220V only, and is the nastiest part of the whole set. In fact it once gave me a bit of a jab, so I am probably not being completely fair when I say it is vile. But while I am repairing them, I always run radios in series with a 60w lamp bulb, to try to limit the current, so it was not as bad as it sounds. Now we are on 230V here I have added a resistor to the circuit so the filaments are not going to get burnt out.
As you say, it's a hybrid set. The semiconductors are these: an AF121 and several AF126S, and some odd diodes that I have never tracked down to my satisfaction. They are all shielded, and are in a beautifully chunky sardine-tin style module.
The more I look at it, the more I think they are not at all FM detection. I think they are the IF stage. They are the wrong components for detection, and it makes me wonder even less about those valves.
The thing at the front that looks like a clockface is connected to the rightmost knob, and it is a rotation mechanism for the ferrite antenne for LW and MW, insidethe set.
There are jack sockets behind for an antenna for SW (I run a thin wire over to the neighbour's chimneystack) and an earth (the gutter drain provides only an ohm or so, now I've scratched off the enamel and put a nice clamp on the bare metal). There is also an input for an old-style piezo-type record player, but it is not a 5-pin DIN.
The controls: the "piano keys" are: On/off, LW, MW, SW, FM, phono, and a defeat key for FM stereo in case of a distant station where tuning in with good sound quality proves to be difficult.
The knobs: Bass and Treble are the first two, and they appear to run a standard eq-type circuit, except there is a reed switch in the treble control whose purpose I have not yet discerned.
Middle knob of the five is volume, but there is a probably-invisible perspex balance-control knob behind it.
Tuning on AM and FM are controlled independently by the last two knobs of the five, but behind the FM one is another perspex knob with two positions for AFC on or off.
In all, it is the most extraordianry radio I have ever met.
Except the 1957 philips set that is on my workbench right now; it appears to have been made out of parts for the American market but produced and sold to Europe: it is utterly mad.