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Old 16th Sep 2008, 8:00 pm   #1
Radio_Dave
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Default Unknown R.A.P. restoration

Hi, Here’s my latest restoration, a post war AC/DC R.A.P. It’s an unknown model but circa 1947.Valves are 6K8G, 6K7, 6Q7GT, 25A6G & PY32()

Chassis:
All the waxies were gutted and re-stuffed on sight, but because the metal cased Sprague caps aren’t as easy to re-stuff, I checked them on the Megger first and only did the ones that failed (around half of them).

The high voltage electrolytic capacitors would not reform and two low voltage ones were open circuit, so they were gutted and new parts hidden inside.

The SPST mains switch switched the negative from the chassis, so I had to change that so the negative is permanently connected to the chassis and the live is now switched. This means there is an extra wire running the length of the chassis and having to use red wires has made this modification very visible, but in the interest of safety, I’m happy to live with it .

The mains dropper resistor was huge, open circuit and irreplaceable. I decided to use a capacitor dropper in its place but I had to disguise it. I covered the additional X2 caps and discharge resistor, on top of the motor run cap, with a piece of plastic tube. I then wound some nylon thread around it, in an attempt to make it look a bit like a WW resistor and then airbrushed the lot in a similar colour to the original part. I also had to put a shunt resistor across the dial lamps as this was, originally, a winding on the now missing resistor dropper. I was able to find a period resistor for this, so again I hope it doesn’t look too obtrusive. A similar, vintage, 33R resistor was used as a surge limiter and was fitted at the rectifier valve socket.

Apart from a clean up with white spirit that was all I had to do with the chassis to get it working.

It was important for me to keep my intrusion and modifications to the chassis as invisible as possible, I’m happy with the result, well, I’d like to think that I’d fool the majority of population anyhow .

Cabinet etc

The cabinet had started to fall apart, so it was re-glued and clamped. The finish was poor so three applications of Nitromours got rid of the majority of it and cellulose thinners with 00000 wire wool got rid of the rest. Nibbles to the veneer were filled and sanded, end grain was painted brown and then four coats of Danish oil were applied, leaving each coat a day to dry.

A new piece of glass was cut to cover the dial and fitted.

One knob was missing so I used plaster of Paris to make a mould and car body filler to cast a new knob. Air bubbles in the mould and then air bubbles in the filler meant that the knob needed a lot of attention to make it look presentable, but I got there in the end. I tried and failed to perfectly mix a paint that matches the original colour, but again I can live with the result.

And finally… at last I hear you cry! The back cover was brittle and smashed. I managed to salvage the bit with the printing on and I rebuilt it using parts cut from an old television back. Edges were bevelled, glued and clamped together. It’s a bit like Frankenstein’s monster, but I'm happy with it.

Here's some before and afters, with the befores on the top

David
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Old 16th Sep 2008, 8:34 pm   #2
Sideband
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Default Re: Unknown R.A.P. restoration

I think you have done a very acceptable job and I admire your attention to detail. The main point is that another piece of radio history has been salvaged and made into a useable set. The cabinet is really excellent and the electrical restoration can only be seen by looking hard. Great work!



Rich.
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Old 16th Sep 2008, 8:51 pm   #3
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Default Re: Unknown R.A.P. restoration

Hi David,
What a great job!
I really like the R.A.P radios and have a three of the more common "Odeon" style ones in my collection plus a very rough console set in the loft.
I do have one the same as yours, sadly with no back but in good condition otherwise, It is strange that RAP didn't put a model number on them, mine has the same printed live chassis warning but beneath that under the socket is a black and brass plate "RAP limited London England" there is provision for a model and serial number but the model number is blank; maybe they were made in such small numbers that it was thought identification would not be a problem?
The only difference I can see is that my set has different colour printing on the scale. does your set have two little paxolin panels underneath covering the chassis screws? Im not sure if there are original or a modification.
Great sets! yours makes mine look a bit faded and dull, I must get some of this Danish oil!
Rich.
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Old 16th Sep 2008, 10:24 pm   #4
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Default Re: Unknown R.A.P. restoration

Hi Rich,

Yes, mine has some paxolin patches that cover the chassis screws. They look like they were intended for some other purpose and have been fitted as an after thought... they didnt'nt cover the grub screws in the knobs though! .

David
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Old 16th Sep 2008, 11:14 pm   #5
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Default Re: Unknown R.A.P. restoration

That's an incredibly nice set you've managed to make there, David, I love the cabinet design.

I think the back is more than acceptable, far better than I could have managed.

I also admire the way you've presented the photos

BTW, how did you come by it?

Nick.
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Old 16th Sep 2008, 11:27 pm   #6
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Default Re: Unknown R.A.P. restoration

Hi Nick,

I got it from Ebay. It was a while ago now and I can't remember how much I paid for it... but it wasn't a lot

David
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Old 17th Sep 2008, 1:32 am   #7
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Default Re: Unknown R.A.P. restoration

Hi David,

Wow! Absolutely fantastic!

I'm not normally a fan of wooden cabinets, but you've done a first class job of restoring yours, it really is superb! And the way you've put that jigsaw of a back panel back together again is simply amazing. I just can't believe from looking at the end result that it was ever in so many pieces!

Congratulations on an excellent restoration, very well done!

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Old 17th Sep 2008, 9:36 am   #8
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Default Re: Unknown R.A.P. restoration

Bought mine as a "British Transport" model, that the workers got at discount. Not sure how true, would love more details though.

David
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Old 17th Sep 2008, 10:11 am   #9
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Default Re: Unknown R.A.P. restoration

Hi, Thanks for all the positive comments

Quote:
Originally Posted by rrdmpb View Post
And the way you've put that jigsaw of a back panel back together again is simply amazing. I just can't believe from looking at the end result that it was ever in so many pieces!
No, I couldn't stick the original pieces back together so I cut three, useful, sections from the back of an old telly and stuck them around the bottom section saved from the original. Luckily the telly back had a very similar slotted hole pattern. I've attached a photo that will explain it better than I can

I've also found some photos of W.I.P on the knob. The first one shows the state of it as it came out of the mould and the last shows it after remedial filling and sanding, just prior to painting.

David
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Old 17th Sep 2008, 11:48 am   #10
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Default Re: Unknown R.A.P. restoration

Hi Dave,

I'm even more interested in this now since picking up a rather neglected RAP console which had been rescued by Howard. Although the chassis is different (one of their 3-section jobs), it appears to have a similar valve line-up to yours and is an AC/DC model with a giant dropper too.

May I ask what speaker this uses? Mine's mains energised, has a transformer mounted on the speaker chassis and uses a 4-way plug to connect it to the chassis. I would also be very grateful if you could take a few resistance readings in that area for me, as everything seems rather O/C in my set

Thanks,
Nick.
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Old 17th Sep 2008, 12:26 pm   #11
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Default Re: Unknown R.A.P. restoration

Nick, I have an 846 (console) model as well, so I'll be able to take readings from both radios. To keep this thread on topic I'll send the results and continue the conversation via PM

David
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Old 17th Sep 2008, 3:13 pm   #12
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Default Re: Unknown R.A.P. restoration

Nice job as ever David!

It would be interesting to see some photos of your chassis Nick, so maybe it's worth starting another thread. It doesn't look or sound like a 846 chassis, although the cabinet looks right. I reckon a lot of these got repaired and cobbled together from what was available at the time, so it might be some kind of hybrid.
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Old 17th Sep 2008, 3:22 pm   #13
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Default Re: Unknown R.A.P. restoration

Thanks David and Patrick. Yes, new thread is called for!

Nick.
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Old 17th Sep 2008, 3:44 pm   #14
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Thumbs up Re: Unknown R.A.P. restoration

Really first class, the attention to detail is amazing
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Old 17th Sep 2008, 7:25 pm   #15
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Default Re: Unknown R.A.P. restoration

Quote:
Originally Posted by Radio_Dave View Post
No, I couldn't stick the original pieces back together so I cut three, useful, sections from the back of an old telly and stuck them around the bottom section saved from the original.
Hi David,

Sorry for my mistake earlier. I understand what you've actually done now. Even so, you've still made a really first class job of it. It looks completely original to me!

Best wishes
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Old 19th Sep 2008, 11:18 am   #16
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Default Re: Unknown R.A.P. restoration

BTW, David's RAP is listed as a 300-R on the Worldwide Vintage Wireless Gallery database - see:
http://www.classaxe.com/wireless/data/sets/
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Old 19th Sep 2008, 5:39 pm   #17
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Default Re: Unknown R.A.P. restoration

Very good !
Is it possible to get white casting resin any where that is suitable for the knobs . paint will discolour/rub off ,which is annoying
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Old 19th Sep 2008, 5:54 pm   #18
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Default Re: Unknown R.A.P. restoration

Quote:
Is it possible to get white casting resin any where that is suitable for the knobs
I've not used it, but Hobby's (www.hobby.uk.com) stock resin and dyes including white. They claim to be UV stable, so should be okay...
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Old 19th Sep 2008, 6:11 pm   #19
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Default Re: Unknown R.A.P. restoration

Quote:
Originally Posted by Patrick Dixon View Post
BTW, David's RAP is listed as a 300-R on the Worldwide Vintage Wireless Gallery database - see:
http://www.classaxe.com/wireless/data/sets/
Thanks Patrick, I did start a thread a while ago to identify the model number and the 300-R was suggested as a possibility. However you link shows the 300-R to be an AC only set and not AC/DC like mine.

Regards
David
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Old 19th Sep 2008, 8:16 pm   #20
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Default Re: Unknown R.A.P. restoration

I'm not confident that the data is accurate to that degree - it doesn't give any valve types for the 300-R.
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