My latest addition - Radialva Groom

[Geaney]

This is another future project. My next door neighbour recovered this from his parents loft and apparently has been there since his grandparents time. The version I have looks like the 1941 model so this is the oldest set I've got. I got the basic info on it and of course it does not have a mains transformer; it does have series filaments, hot chassis, resistive mains cable, etc. Looks like I'll need an isolation transformer set up soon. This is also my first Bakelite cab so no woodwork on this one!

It comes complete with the original carrying case - I've seen two different types online - a leather version and the wooden one that I have.

I've had the chassis out and did a quick clean up. Things are certainly packed in tightly in such a small space. It runs on 110v so I'll be running it off the variac for a while once I start on it. The service sheet kindly gives the resistor values to add for running of different mains voltages up to 250v.

I'll confess I'm a bit nervous about keeping the resistive mains cable - it being over 70 years old, etc. It looks to be in good condition but I've no idea how to test it. Any experiences or suggestions with these mains leads would be most appreciated.

Cheers, John

[Yorkie]

Looks in remarkably good condition John, and in its storage box!

As to the 'line cord' I think that most restorers tend to replace it with a capacitive dropper. Often - unlike yours - the line cords are not in good condition and have sometimes been cut short by people who don't appreciate that the line cord performs a vital function in reducing the mains voltage. I know that some restorers get rather alarmist about line cords, but if you think about it - apart from possible (probable?) deterioration with age, and perhaps the use of questionable insulation materials (asbestos?), a line cord is little different in principle from an electric blanket element.

That said, for me, safefty scores over originality every time, so personally, I'd go for the capacitive dropper arrangement, then you can fit a normal twin-core mains lead and plug.

Just my thoughts on the matter - others may see it differently.

[Mark R]

Nice radio is that John.

cheers Mark

[Bushbaby]

Hi John,
Nice radio - want to swap??

I had the same feeling when I bought my little champion set with the resistive line cord (the Amercians called these sets 'curtain burners') so I was very apprehensive about using it. Although not original, Ed Dinning made me an autotransformer to suit and this made me much happier about the set all round.

I agree with David that a cap dropper is good way to get around this.

Hope this helps

Rob

[Geaney]

Thanks David, Rob,

Cap dropper it is then for the mains reduction strategy - so the mains cable will be replaced.

I put a first clip up online for anyone who wants a closer look

http://www.youtube.com/watch?v=5ucV8TTKT6Q

Cheers, John

[Bushbaby]

Hi John,
Thanks for the clip.
It does appear that they packed a lot of components into a very small space!

Regards

Rob

[Yorkie]

Thanks for the video John.

As to not being able to alter the alignment, it having been sealed at the factory, I think it unlikely that it will have altered over time. No doubt the coils will have been Litz wire, dipped in wax, and the caps, silver mica ones, which are very stable. When you get round to checking the alignment, hopefully it will still be bang on. At least being factory sealed it will have not at any stage fallen victim to the 'phantom fiddler'!

I think the biggest challenge might be the dial, with the white station names having flaked off, as so may dials tend to do. Conventional printing using waterslide transfers is out of the question due to being unable to print white, and screen printing for one-off dials is prohibitively expensive, even if you prepare the artwork yourself. There is a type of printing where you can print a colour then quickly sprinkle white embossing powder onto the paper while the ink is still wet. You then heat up the embossing powder and it melts onto the paper. Frankly, it sounds like a recipe for failure! Whether it would work with water-slide tranfer paper I've no idea.

I'm sure you'll find a way of overcoming this conundrum - you aren't one to throw in the towel!!

I'll watch this space with interest

[Geaney]

Just realized I got the name wrong - its Radialva. I seem to have inserted an additional 'i' long the way. Apologies. I don't seem to be able to edit the title of the post.

Cheers, John

[Joe]

Fixed, John.

- Joe

[Geaney]

Guys, I have a question on capacitor voltage ratings - the paper waxes in this set are mostly rated at 750V but some are rated as high as 2000V. According to the circuit diagram the B+ is 105V. Am I OK to re-cap using the regular 650V rated components? I can't see why the existing ones are rated for such a high voltage.

Because of the small space, there are three layers of components in places so the top two have to be moved out of the way to get at the bottom ones, etc. I really don't want to have to do this twice so I'm hoping I'm OK with the 650V caps.

All advice on this is much appreciated.

Regards, John