Ekco AC77

[Yorkie]

Thanks for reading the post Dave, which might act as a spur to encourage me to get on with the AC77 and see the job through!

It will be evident in reading earlier posts in this thread that I've put in many hours of work to get to this stage, but it's been spasmodic. Along the way, there have been other diversions - some related to this project - for example, to re-wind the field coil I made a coil winder driven by a sewing machine motor, which became a project it its own right, then I wrote that up as an article which was published in the BVWS Bulletin. Likewise, when I'd obtained some valves of unknown provenance and wanted to test them, my Taylor 45D Valve Tester didn't have sockets for B4, B5 and B7 bases, (even though the Taylor Switch Setting Book had the settings and data for the vales) so I designed and made some adaptors and again, wrote that up to be published in the Bulletin.

One of my concerns was whether the Bandpass Filter Unit which is at the heart of the front end, was sound or defective. If it was duff, that would be curtains, as it's such a rat's nest inside that it would be beyond my wit to repair it. (The maker's original manual says 'don't attempt any repairs - return to the factory'). Earlier this year I checked it out with an Ohmmeter and the results weren't hopeful. I opened it up and the band-switch appeared to be fully encased in metal. However, on closer examination it was sealed with a ring on brown waxed paper around the periphery on the switch. I removed that, and  gave the switch contacts a liberal dose of Servisol while operating the switch. That restored to resistance chart to something like it should be, so I'm hoping that ultimately, that will prove successful. (results attached). I've done no work on it since then.

Turning to the pilot bulb, the bulb-holder in the unrestored chassis picture shown below is the original holder - a normal sized Bakelite bayonet cap as we could buy today, but the bulb was missing. The instructions state: 'This is a special Ensign 200V 12 Watt type connected in such a way that it always receives the proper Voltage if the correct mains tapping is used'. Obviously such a bulb is unobtainable today - the nearest equivalent being a pigmy bulb as used in 'fridges and the like, but they're 15Watt - albeit the bulb will be running on 200V - not 240V, which will de-rate it slightly, but the glassware is quite 'bulbous', so  an alternative might be an elongated sewing machine bulb, which of course have MES bases rather than full sized BC bases, so some adaptation would be needed there, and again, such bulbs are 15W not 12W. There is a heat shield which fits around the metal tube into which the bulb is pushed. I've placed a bulb in the heat shield to show the physical size of the bulb in the pic below, though the bulb is actually located in the tube where the holder is shown in the unrestored chassis pic). I don't think a pigmy bulb is really a runner - I think it would both give too much light, generate too much heat and soon burn out.

All in all, this set wasn't Ekco's finest hour, which is why I guess that thought not valuable as compared with the round Ekcos (of which sets such as the AD65 are just as abominable, with a messy rat's nest beneath the chassis), the A77 is nevertheless uncommon, and for me at any rate, historically worthy of restoring.  I think Ekco's high watermark in terms of thoughtful design and construction is without doubt the A22 - a delight to work on.

Due to other distractions and projects, (the latest of which is to restore a basket case KB 'Toaster' radio bought for a fiver at Golborne), the A77 has languished, but I hope to get back to it over the winter.

I've attached a few pics to help make sense of the above verbose text, which I hope might be of interest.