EKCO AD75 Restoration

[Dickie]

A little more progress on this. In the end I decided to respray the top of the chassis and leave the underside as is. I couldn't face the prospect of stripping everything out of the chassis and rebuilding the whole thing. Ditto in restuffing the capacitors visible on the top and not on the underside. A bit like sitting on the fence, but I'm happy with the result! The CBL31 was reinstated and all the mains and perished wiring replaced with silicon rubber insulated stuff. Also all the old waxies and a few resistors that had gone high.

I have gently powered it up on a variac, to be greeted with no smoke nor bangs. It works on MW, picking up the usual talksport and radio5live transmissions that would blast through anything. It's a bit quiet though, and there's rather a lot of pops and crackles. absolutely nothing on LW. So its a case of so far so good, but there's quite a lot to be sorted out.

[stevehertz]

Nice job.

[G6Tanuki]

I see some legacy tar-bombs and Waxies and flat brown-biscuits [which were often paper] capacitors there.

And plenty of old resistors that could have drifted-high over the last 70 years. A while back I traced horrible deafness in a radio because the screen-feed resistor [which fed both the frequency-changer and the IF amp] had gone from its specified 33KOhm to something like 240KOhm...

Doing the job properly - fitting separate resistors for the FC and the IF stages, with separate decoupling capacitors, got the gain back up.

[Dickie]

Thanks, I will take your comments on board. The only waxies you can see have been restuffed, and I have checked and replaced as necessary all the resistors. As for the other bits, time will tell.

[Dickie]

I think I've now got this back to good health. The pops and crackles were down to a noisy wavechange switch and the deafness disappeared after a slight adjustment to the 1st IFT alignment. I also replaced a couple of "micafil" capacitors which didn't give any improvement so probably wasn't necessary. On soak test I found the set was prone to instability and motor-boating at the LF end of the medium wave. This frustated me for a while as I had replaced all of the decoupling capacitors and didn't know what to attack next. However, I had failed to notice that in simply snipping out the two mains filter capacitors C25 and C26 (post 19 refers) left a totally unfiltered line running from the loudspeaker to the aerial input circuit. Doh! As a trial I fitted a couple of 0.1uf Y2 caps in place of c25/26 ( that was all that was to hand) and all was stable. So I let it run for a couple of hours with no issue.
Its now back in its cabinet, back on, and sports some non-original knobs that aren't too far off the correct parts. In conclusion, I'd like to thank all the forum members who helped me out with this restoration, in particular

Welsh Anorak - Glyn, Who sold me the kit of parts to start with,
PJFradios - who unwittingly gave me a scrap set that yielded a suitable loudspeaker,
Phil G4SPZ - Phil Harris, who provided me with a number of pictures and scans of the rear panel,
David G4EBT - David, without whose bulletin article and example I would never have attempted to rout out a rear panel,
llama -Graham, who supplied me with a valveholder completely FOC,
and Pamphonica - Jeremy, who sent me some silicone-rubber wire in between swapmeets to keep me going, again FOC

[Station X]

That's looking great and the knobs don't look too far out of place.

[Phil G4SPZ]

First class job! I reckon those knobs are bang-on too. Here’s what the originals look like.

Phil

[stevehertz]

Phil I can't be 100% sure but I don't think those knobs are original. They're very close and I know many of them are used as replacements for the harder to find Ekco ones. The salient point being that they are slightly different to the larger tuning knob. As far as I know most (all?) Ekco sets like the one in question use a set of three knobs all, in effect, 'the same' with exception that the tuning knob is otherwise larger. Saying all that, they are an ideal replacement and I myself have a pair on one of my Bakelite Ekcos, an AC85. It would be interesting to identify what make of set these similar ones are from, or they may be generic ones as were available from from radio parts suppliers.

[Phil G4SPZ]

Hi Steve. Thanks for that information. My photo was of the Museum’s AD75 which I restored some years ago, and the knobs came with the set, so I just assumed they were original.

The reason I only showed two knobs in the picture is that the third one has annoyingly disappeared, either by careless handling by Museum staff (which I doubt) but more likely through pilfering.

I need to source a replacement - a matching pair of the small ones - so if anyone has any, or other ideas for replacement, I’d love to know. I’ll post a ‘wanted’ message in due course.

Finally, the AD75 is probably my favourite of the round Ekcos, but the only thing that lets it down is the lack of an illuminated dial. However the design was ‘down to a price’ and such unnecessary frills were omitted.

[Dickie]

Chrispy57 may be able to help you out with a couple of near-enough knobs:

https://www.vintage-radio.net/forum/...d.php?t=205431

[Dickie]

Originally Posted by Phil G4SPZ

...... Finally, the AD75 is probably my favourite of the round Ekcos, but the only thing that lets it down is the lack of an illuminated dial. However the design was ‘down to a price’ and such unnecessary frills were omitted.

Yes, designed down to a price, but why add the luxury of a mains RFI filter?

[Phil G4SPZ]

Good design - kept the performance aspects but discarded the unnecessary?

Thank you for the knob info, I have followed that up.

[Lloyd 1985]

Here’s a photo of the knobs on my set, just for reference! Note the wavechange knob has coloured dots on it to tell you what wave band you are on.

Regards
Lloyd

[stevehertz]

Yep, those are the right ones

[Phil G4SPZ]

Thanks, Lloyd. Very helpful.

[Techman]

Originally Posted by Phil G4SPZ

Finally, the AD75 is probably my favourite of the round Ekcos, but the only thing that lets it down is the lack of an illuminated dial. However the design was ‘down to a price’ and such unnecessary frills were omitted.

Yes, I've got a couple like that, an annoying feature...or lack of! One is a pre-war GEC, which would have had this annoying feature if some long gone previous owner hadn't fitted, or had fitted a homemade one on a crude bracket at the rear of the dial. The second example that comes to mind is a recent acquisition, an HMV 1508, which extremely annoyingly has a bulb lighting a rather useless red warning light at the top of the dial, but made so that it doesn't actually illuminate the dial itself. This is HMV...what were they thinking? This now reminds me that I need to start a thread on this table radiogram, as there's a couple of questions that I could do with asking regarding it.

[David G4EBT]

Excellent end result of a very comprehensive multi-faceted restoration Richard.

You did a splendid job of masking off and respraying the top of the chassis - it seems to be a feature of older Ekcos that the original paint job was poor, and over time they become badly pitted with rust. Some years ago Gary Tempest tipped me off that the closest match he could find to the Ekco chassis paint colour was Halfords own brand of Ford 'Dove Grey'.

Some years ago had an Ecko A77 with a separate power supply and receiver chassis, both of which were badly pitted with rust. I stripped, de-rusted with a power-file, primed and resprayed both chassis in Dove Grey. Makes all the difference. (Not really a memorable Ekco radio on which to spend so much time and effort to restore, compared to a 'roundie'!).

I think the easiest Ekco 'roundie' restoration is the A22.

AC only, with with most components on a tag-strip around the outer perimeter of the circular chassis 'pan'.

[stevehertz]

Originally Posted by Phil G4SPZ

First class job! I reckon those knobs are bang-on too. Here’s what the originals look like.

Phil

To clarify the situation or difference between these knobs. The knob on the left is the 'proper' Ekco knob. To the right there are two different sizes of a knob type that is often used for replacement purposes on Ekco sets, both of which will 'work' as near replacements, one being slightly smaller and the other larger. At a glance you'd be pushed to notice the difference, but saying that once you are aware of the difference it sticks out like a sore thumb!

If anyone knows the origin of the 'replacement' ones it would be interesting to know. They may even be Ekco knobs from another era/range of sets. Anyone recognise them?

[Phil G4SPZ]

Hi Steve,

Having perused a number of photographs of the AD75, you are absolutely correct. However whilst browsing I did see a photo of a set with knobs more akin to the ones in the Museum. I wonder if Ekco actually fitted different knobs during the run of production? As you say, they're close and acceptable but not absolutely correct, however for the Museum's purposes I doubt that any visitor (yourself excluded, Steve!) would spot the difference.

I don't remember the band switch colour dots on ours. This is the knob that has gone missing. Anyway, it's academic now as I'm negotiating with Chrispy57 regarding replacements.