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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only.

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Old 22nd Feb 2018, 1:07 pm   #1
cathoderay57
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Join Date: Oct 2017
Location: Bristol, UK.
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Default Ekco PB189 Resto

Hello, I'm just finishing restoration of an Ekco PB189. In the past I've avoided motor tuned sets because of the complications, both mechanical and electronic, that can sometimes be encountered but this one was in very good condition mechanically (disc and contacts all present and correct) so I decided to have a go.

There seem to be a few of these around, and while this type has been covered on the Forum before, I thought I'd pass on the issues some of which had me foxed for a little while. The first thing I found was the HT cap had been replaced by a 32+32mfd electrolytic. This capacitance is a bit high for the rectifier (DW4/350) so I replaced the cap with a 16+16. On soak test on the VCM163 the DW4/350 dropped on both anodes to about 25% so I rejected it and fitted a decent RV120/350. Lots of the other capacitors had already been replaced but some with incorrect values, voltages or types so I swapped them out for better ones.

On test I could get nothing on LW or SW - only MW. After a lot of poking about and drawing out the wavechange switch connections I realized that most of the wires had been removed and resoldered by a previous restorer, but the connections to the LW and SW oscillator coils had been transposed. SW was OK and LW then gave lots of noise, but no Radio 4. Retuning osc trimmers wouldn't bring it in. So off with the oscillator can and a look at the padders. They were not (as expected) pyjama buttons but Austrian "Sator" makes, probably silver mica sandwiched between 2 outer wafers of paxolin. On test on my Avo bridge the LW and MW padders were way off value so I fitted silver mica replacements. That improved things. IF alignment went OK but I could not get L19, the frequency compensator, to do anything at all. The 2 issues were that the 2D4B discriminator had dirty pins and was giving zero output, and a long time ago the original cap on L19 (again probably a pyjama) had been replaced by a ceramic of the wrong value, so freq compensation would probably not have worked for years. Putting in a 140pF silver mica enabled alignment.

Happy days - it all now works well.

Cheers, Jerry
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Old 23rd Feb 2018, 9:28 am   #2
vinrads
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Default Re: Ekco PB189 Resto

A very nice read Jerry, and well done with the restoration I always check the value of replaced reservoir capacitor if a replacement has been fitted, I too like the vintage of Ekco radios.

I have on the bench at the moment an Ekco PB515. Motor tuned and the clever thing is it automatically changes the waveband, having fun trying to fit relays to eliminate the sparks and flashes on the selector mech, not easy due to an AC content on the switching voltage, may have to look for a low voltage AC coil relay or two.

Mick.
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Old 23rd Feb 2018, 12:58 pm   #3
cathoderay57
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Join Date: Oct 2017
Location: Bristol, UK.
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Default Re: Ekco PB189 Resto

Hi Mick, I've not seen a PB515 before - a fairly rare beast perhaps? I didn't recognise the cabinet in the pic on the Radio Museum website. Push-pull output with EL3 pentodes it should sound good. Looks like a super-duper version of the PB510 which has single Class A EL3 output and no magic eye (Trader Sheet 684). I didn't realize Ekco made so many varieties of motor-tuned set. With side contact valves I always end up spending ages trying to clean and re-seat the valve holder contacts. Good luck.
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