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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only.

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Old 24th Aug 2013, 6:28 pm   #21
Goodfellas
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Default Re: "Universal" valve radio

Ok thanks, I haven't seen one like that before.
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Old 24th Aug 2013, 7:20 pm   #22
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Default Re: "Universal" valve radio

I intend to use this is a radio on a regular basis, so the first job is to replace the caps on the HT side and any leaky ones (previosuly recommended by others in this thread).
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Old 24th Aug 2013, 7:49 pm   #23
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Default Re: "Universal" valve radio

I'm going to hazard a guess here that one of the triodes in the CV1932 is being used as a leaky-grid detector and the other is used as output. I very vaguely remember something like this in a 50's kit design.


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Old 24th Aug 2013, 8:10 pm   #24
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Default Re: "Universal" valve radio

You may also find that the rectifier is below par too.

Nick.
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Old 24th Aug 2013, 8:59 pm   #25
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Default Re: "Universal" valve radio

Below par from a design point of view? Or due to age?

I don't mind if the design of this radio is quite basic or in poor condition, hopefully this will be a good exercise to farmiliarise myself with valve radio repair/restoration.
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Old 24th Aug 2013, 10:15 pm   #26
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Default Re: "Universal" valve radio

Please Please check that the mains Neutral is going to chassis, the neon screwdriver seems to indicate otherwise .

Change those wax capacitors and also the Brown coloured capacitors - they look like Hunts Mould-seals which by now will be behaving like resistors rather than capacitors. What ever you do, do not touch the metal rectifier with the radio powered as this could kill you! Fit a solid state diode with a 100 Ohm wire wound resistor in series, there are posts on this Forum that cover this aspect. Completely isolate the metal rectifier from circuit - you could do what I did with a similar radio - I kept it in physical position but not wired, to retain some of its vintage charm .

It might be a good idea to draw the circuit diagram from what you have now, it is not too difficult for such a simple radio. You will then be able to study it, put it on this Forum even, the colossal amount of technical knowledge available here will be able to suggest improvements or highlight areas of poor circuit design to make the radio better.

I love these old sets as they are such a lovely challenge.

I will attach a circuit of my kit 'Premier' radio, the great thing about kit radios is that you can do whatever you like with the circuit. No need for originality as after all - it is a kit radio
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Old 24th Aug 2013, 10:35 pm   #27
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Default Re: "Universal" valve radio

A lot of these sets used similar circuits as well so the circuit shown above may very closely match yours. There were some interesting valve combinations used depending on what was available/cheapest.

There were other kit sets that used the same cabinet.

Rich
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Old 24th Aug 2013, 11:27 pm   #28
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Default Re: "Universal" valve radio

Thanks Top Cap for the advice, and rest assured I will be taking the upmost care when working on it.

And regarding originality, I agree, I prefer the idea of keeping the design of normal production radios in an original state, even when there's an occasional desire to modify them. I'd feel too guilty if i did this.

But with this non-standard kit radio I would feel less guilty to making any changes. In fact, I may add illumination for the tuning dial (which will also illuminate the red bezel between the two control knobs). Perhaps a couple of neon bulbs for a subtle glow, or a low voltage bulb if I can tap the supply from the transformer (without overloading it). Or another way if I can find it.

Also, I do plan to draw a circuit diagram of this radio, which will be interesting.

Cheers for the schematic, this will give me a good basic overview.
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Old 25th Aug 2013, 12:22 pm   #29
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Default Re: "Universal" valve radio

For adding low voltage illumination without adding (much) load, LEDs can be very handy. Two or four in inverse parallel with a suitable series resistor work nicely on 6.3Vac.
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Old 27th Aug 2013, 11:13 pm   #30
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Default Re: "Universal" valve radio

Quote:
Originally Posted by Sideband View Post
There were other kit sets that used the same cabinet.
Rich
I had one of these kits when "I were a lad". Which was in the early 1970's. However I don't recall ever building it sucessfully and getting it to work.

However - though the moulding and basic interior look familiar, it was obviously available in different colours. This one is chocolate brown, but mine was much lighter - a sort of creamy pale beige as I remember it.

It was always a very short cabinet for those huge great octal-based bottles! I would have thought that it would suffer bad overheating issues if actually used as a radio for lengthy periods.

Steve
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Old 28th Aug 2013, 7:52 pm   #31
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Default Re: "Universal" valve radio

The cabinet was on offer from numerous dealers in the early-ish 1950s in either brown (possibly mottled, but I can't be sure) and in 'cream' which was probably Urea rather than Phenol.
With the odd line-up of valves, I think it might be best to start afresh and use the cabinet, chassis and numerous parts to build a three-valve plus rectifier TRF. If there's a problem with valve height, the use of GT octals would perhaps be best.
Its worth pointing out that it is quite possible to build a set without a fully isolated mains transformer and yet keep the chassis held off the mains (by capacitors and the use of a bus bar ground).
Tony
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Old 29th Aug 2013, 9:59 am   #32
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Default Re: "Universal" valve radio

Got a new soldering iron tip today, so I'll be able to start replacing the HT caps and also the one on the aeriel. I will work through the rest of the caps in stages so I can see how each step helps.
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