Bush AC3 Cathedral Restoration

[TriMan66]

Hi All,

I have finally taken the plunge to restore this classic radio. After years of looking at it, in its sad state, its now time to bring it back to life.
See the pictures below, it truly was in a bad state and was recovered from someone's back shed, literally full of dirt and crud. I could see the potential when I bought it, however it has taken me some time for it to move to the top of my list.

I put a post up in 2012 asking for information about the obvious connection between the American Gecophone S5 radio. It would seem to appear that Bush contracted Gecophone for the design of the case for their first radio model. I understand the AC3 is Bush's first radio.

Lots more to come....

Craig

[Radio_Dave]

That's a rare and, probably, a very valuable radio. Personally I'd do absolutely nothing to it, electrically or visually, apart from a bit of a clean and wax polish.

Preservation may be a better idea, instead of a restoration.

David

[TriMan66]

Hi Dave,

I appreciate where you are coming from. However, I do wish to breath some life into this set, since it sits in my work shed, and I really love the idea of actually using these old sets to listen to the radio with.
It is a three valve TRF with reaction style volume, and it's an early set, so I'm not expecting great performance, but still more than listenable to.

The pictures below show the state of the cabinet too. It needs a gentle rub down and a re-finish on the wood work.
I will also be looking to repair the missing piece of the repwood fretwork.

As for rare, there is another post on this site which says there were only 6 made! I doubt that very much indeed. It is a rare set, but not that rare!!!!!

Craig

[murphymad]

Hello Triman,

I have been working on one of these for another forum member and I am positive that I have seen more than six of these radios belonging to different people over the years, so there will certainly have been many of them made.

I have the service data for it if you need it.

Best regards,

Mike...

[mark pirate]

Originally Posted by Radio_Dave

That's a rare and, probably, a very valuable radio

I agree, the last one I saw fetched over £300, and was not in much better condition!

Personally I see nothing wrong with restoring it, but if it were mine I would leave the cabinet to an expert.

Mark

[Paul_RK]

The American set was an Echophone, not Gecophone: at least I'm not aware of any connection between them. Potentially a lovely cabinet either way, and all the better for having a Bush chassis - I look forward to details of the restoration. I'm another who would chicken out of attempting the cabinet myself, only because my skills with wooden things are rudimentary at best. It's understandably a sought-after model, but doesn't seem nearly so rare as to require it to be left in that condition!

Paul

[TriMan66]

Hi,

Thanks Mike for the offer of the schematic. Its not in the usual BVWS collection but I did get one from the radiomuseum website. If you did have any more service information, that would be great.

Paul, you are correct, I got mixed up between Gecophone and Echophone. I re-attached the photo again just to see the obvious similarity between the S5 and the AC3.

Also, if you look carefully at the second picture in post 3 which shows the back of the cabinet and the insides. There is a wire running diagonally along the back with some white "stuff" tangled in it. Have a look at the photos below which show more clearly what the "stuff" is!!!

Craig

[Radio_Dave]

It could just be string to pack out the cable or to add strength. I doubt it's anything nasty, like asbestos, but you could try lighting it with a match to make sure it burns.

David

[HamishBoxer]

That "Stuff" looks like bone of dead vermin.

[PJL]

The cabinet needs an original finish which was probably tinted nitro-cellulose lacquers.

[TriMan66]

Hi All,

The "stuff" is indeed a small collection of bones. My theory being a bird got entabled in the that wire and came to its final end, leaving only the leg bones behind.

Now the actual chassis. I was pleasantly surprised to find the knobs simply unscrewed! No fighting with grub screws welded to their respective shafts with years of rust build up. These pictures are after lot of the build up dirt and dust has already been removed.

Notice that it has already been repaired at least once in the past and the original capacitor cans are missing from the chassis. I'll dig around and see if I have something that at least looks the part for this vintage. The supply is C-L-C smoothed and those two capacitors are both 8uF.

The other observation is that the rubber used for wires and gromets has now all perished. The cable to the speaker specifically is in a bad way.

Craig

[HamishBoxer]

Does not look bad under the chassis and a very worthy restoration.

[TriMan66]

Hi PJL,

Thanks for the advice on finishing. I have not at this stage decided how to finish the woodwork and I am happy to take advice. My first thoughts were to gently rub it down and simply oil the wood, since its actaully in really good nick. The photos don't do it justice, its a dark wood with a tinge of red.

I rubbed a small patch with very fine sandpaper and applied a damp cloth to see what an oil finish would look like and it really was a beautiful finish.

The base plinth is made of a much lighter coloured wood and needs to be effectively "painted" black or probably better a very dark brown.

Notice the top has a cutout of veneer added, when damp from the cloth this was not particulary noticable. Certainly nowhere as much as in the photo.

Anyway, at this stage the wood work is minor distraction, on with the chassis first.

regards
Craig

[TriMan66]

Hi,

The valve lineup for this model is:
DW3, S4VA, S4VA and a PM24M.
What was in my set was:
U12, MS-PEN, S4VB and a PM24M.

I replaced the two electros which were older replacements themselves. As you see more clearly the two holes for the original cans. The circuit calls for two 8uF caps, and I used a 10uF on the U12 side and 22uF on the other side of the smoothing choke. That should be well within the capacitive loading for U12 and fine for the original DW3 if it were to be replaced.

With all the other valves removed, I wound up the variac slowly to apply the first power to this radio for quite some time I expect. All good, all these valves are 4V varieties and the heater volts are fine. The U12 looks to be strong too and the unloaded DC volts was approximately 330V.

Step 1 complete. I need to look for those capacitor cans.

Craig

[TriMan66]

Hi All,

So before I share with you the electrical restoration, some words on the approach I take.
I have to say I did laugh quite a bit when I read Chas talking about those with CCRD, which is Compulsive Capacitor Replacement Disorder. My time is too precious to me and I will put my hand up as I fall into the CCRD camp.
An original capacitor may measure in value with no significant resistance on a low voltage LCR meter/bridge. One may even take the trouble to measure its capacitance/resistance under high voltage conditions and convince yourself that it is still OK. But I cannot afford the time later (week/month/year) to find a component which subsequently fails when put under high voltage conditions again after such a long time sitting idle. And this set is more than 80 years old.
So that said, I replace all caps on sight. That's under the chassis. I do want the top of the chassis to look as authentic as possible when viewed from the back. Especially given how rare this set is and that this model does not come with a back cover.
I'll put up some pictures soon.

Craig

[ThePillenwerfer]

I'd advise against Danish oil and the like as it's non-reversible. It soaks into the wood and cures so can't subsequently be sanded or stripped of.

If it were mine I'd do it with shellac. It's not authentic but is easy for a future, more skilled, restorer to remove and do a better job.

I'm with you on changing the caps though.

- Joe

[PJL]

Just don't try to stain the wood unless you know what you are doing as the finish was tinted to a dark brown.

[Radio_Dave]

Originally Posted by TriMan66

The base plinth is made of a much lighter coloured wood and needs to be effectively "painted" black or probably better a very dark brown.
Notice the top has a cutout of veneer added, when damp from the cloth this was not particulary noticable. Certainly nowhere as much as in the photo.

Lots of pre war radios only had fancy veneer on the front. The sides were then finished with a heavily toned lacquer to hide the mismatch of materials and in your case, a patch in the veneer.

I'm a huge fan of Danish oil but I have to agree with Joe and say oil just isn't the right choice for this radio.

David

[Paul_RK]

Looks from the photos in post 7 that the front of the radio was fairly plain as regards veneering, if veneered at all, but at least it won't have been patched! I've come across prominent triangular patching of veneer even on the shoulders of a (Defiant) console set, where the original finish was so dark as to hide the makeshift veneers. Seems to suit the design of this cabinet that the grain of the front is quite plain, so that it doesn't compete for attention with the far from ordinary fretwork.

Can't abide Danish oil myself on anything pre-1960, which is neither here nor there, but the permanence of the treatment may indeed be a valid deterrent in this case.

Paul

[TriMan66]

Hi Guys,
Thanks for comments on the finish and specificially the oil approach. I am still undecided what to do and I want to see the cabinet fully rubbed down. All comments are much appreciated.

My only comment is that if the wood after the oil finish is lighter than the original dark finish applied, there is still the opportunity to apply a lacquer coat at some later stage to make a more original finish.

It just seems a shame to cover over such a lovely veneer with a dark lacquer and hide everything. The case in point is what Paul said abut the front, under all that original dark lacquer is actually some rather nice veneer (I had a little sand to see).

Here's a question I have toyed with. Do we really know they left the showroom with such a dark coat, or have they darkened over the years naturally, including the obligatory nicotine smoke they have been subjected to.

I have attached a random example of what looks to me like an oiled radio. See the detail in the front panel which is similar to this set which will be lost with a dark laquer. Also note the base plinth has that dark brown "paint" style effect which would hide the light coloured wood I mentioned earlier.

Craig