Riviera Radio Receiver
Need to construct a better chassis for this Riviera Radio receiver, the present circuit resembles the battery version of the KB Pup.
I've tested the tuned circuit and it's hopeless, there's something not right with the coil. I don't expect to tuning to be all that sharp but this one hasn't any selectivity whatsoever. Like the Pup two triodes are employed. It's the usual arrangement, leaky grid detector with reaction which is transformer coupled to the output valve. The transformer has open circuit windings.
The problem here in the North-East is that three stations are grouped very close together and simple TRF radios have difficulty separating them. The Philips "Superinductance" sets can though
Tuning coil resistances are 2.5 ohms for the medium waveband and 51 ohms for the long waveband, the latter seems to be too high.
Using a signal generator the medium waveband coverage is proven to be 600 to 1300Khz. Medium waves is marked as "SW" on this made in 1930 set.
Switch to LW, set the signal generator to 200Khz. No resonance at that frequency, instead the 'scope is showing a modulated waveform irrespective of the position of the tuning capacitor.
That's curious looking set!
Is that its own cabinet? Or a repurposed one from something else?
Any clues to the quite large discrepancy over the coil resistance?
Hi Marion, the Riviera Radio was made by the British Radiophone Company which in due course evolved into the well known Plessey company. Like certain KB radios the Riviera was acquired by saving up cigarette coupons.
I bought the set simply for it's looks knowing the innards are just simply junk. so the choice is restore the existing electronics or build in something better?
From Grace's guide: https://www.gracesguide.co.uk/Plessey_Co
Yeah! That's a lot to read at bedtime!
Now then, surely, the fun is to get the junk working properly again? - I remember being cock-a-hoop at getting a few crackles out of a crystal lash-up, let alone to be able to listen to an entire programme on it!
I reckon, let's first see what it can be made to perform like in its original guise, and only then consider new 'guts' for it if it can't be revived?
Hi Frank, indeed, the time has come has come to make use of the 1D8GT valve and it's application can be in the Riviera Radio receiver. The tuning coils have been sorted out and are giving full coverage on both wavebands so I can implement Marion's suggestion of retaining much of the original design. The circuit diagram shows a leaky grid detector which requires reaction to sharpen up the tuning. The detector introduces damping on the preceding tuned circuit and a bit of positive feedback will improve the Q of the circuit. An anode bend detector is out of the question for this type of receiver and in fact I don't know of any battery radio receiver that has ever used such a detector.
Did Philips make battery Superinductance radios?
I know little, nothing, about the Superinductance radios.
An anode bend detector is perhaps not the best with the way modern MW stations compress the audio to the max and probably increase the modulation aswell.
Not tried it but I think that type of detection would not handle that signal well.
Hi Frank, the Philips "Superinductance" radios are truly impressive performers, even the earliest models such the 834A have good selectivity, maybe not as good as a superhet receiver but nevertheless not that far behind.
Later models like the 472A do perform as well as any superhet. Even have AVC.
Getting back to the Riviera Radio, the audio coupling transformer has open circuit windings and will need rewinding.