Philco 580 Radio

[Yorkie]

A few pictures, and a couple of questions, the wave change knob broke, it was brittle, but something tells me it is not the correct knob, also what is the red and black input/output on the rear panel, I have worked the rest out.
I am going to make a start on this tonight, the seller said it was refurbished 20 years ago, but it seems full of original paper waxies.

I can explain the red and black sockets on the rear apron - they're for a 'Philco All Purpose Aerial' which I assume was an optional accessory - probably a frame aerial, perhaps with a tuning cap to peak it at the station to which the set was tuned, though that's conjecture on my part.

To quote:

Aerial connections are provided for the Philco All Purpose Aerial, the aerial being selected and operated by the wavechange switch. the connections for this aerial are the red and black sockets on the terminal at the back of the chassis. Normal aerial and earth systems should be connected to the A & E sockets'.

End quote.

http://www.radiomanuals.info/information...%20580.pdf

As to the 'original paper waxy caps' I suppose they could have been re-stuffed 20 years ago, but personally, I'd disregard any comments made by the seller, and assume that the set needs to be fully restored. There are of course different views as to what should be done with classic sets rather than just any old radio, and IMHO, the older the set is, the more the emphasis should be on 'conservation' than 'restoration. By that, I mean that as much of the original set should be tested and conserved as far as possible, (as a listed building or piece of antique furniture might be) rather than to routinely yank out and replace all caps and many resistors, as we might do with something as commonplace and ordinary as a DAC90A.

Assuming that the speaker field coil (L15) is still intact, do bear in mind that the full (un-smoothed DC) HT current with 100Hz ripple passes through that coil, which doubles as a smoothing choke. Hence, if the paper caps are leaky, they will pass DC current as well as AC signals, and as well as for example, plonking DC on the output valve grid, will cause excess HT current to flow which will stress the field coil and risk burning it out. It consists of thousands of turns of very fine wire so a rewind isn't a DIY prospect, though you can get them rewound (at a price).

Much better to resist the temptation to run the set for any length of time until the paper caps have been replaced or at least tested for leakage at their working voltage to see if they're worth leaving in situ.

If - as is possible - any perished rubber wiring needs replacement, I can recommend the silicon insulated multi-strand wire, which comes in two gauges and several vintage colours, as sold by Phil Marrison ('SWB18' on 'the other side of the wall'). It's heatproof, strips very easily and really looks in keeping.

Sorry I can't comment on the knobs. (You can get any knob made to a pattern by Ben Djikman).

Hope these ramblings are of help.

Best of luck with the restoration!