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Old 10th Mar 2019, 3:03 pm   #21
ekjdm14
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Default Re: Ferranti U1003 basket case radio

Brilliant, I wish I had the equipment (and mainly the patience) to properly reform caps. The only successful reforming I have done is via the dim-bulb-for-ten-minutes, allow to cool, full mains until warm then allow to cool, rinse & repeat until either it stays cool or I decide it's not going to work.

How does one go about replacing the cap in the ratio detector, is it inside the FM tuner?

It's surprising how well the other caps have been resilient over the years.
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Old 10th Mar 2019, 3:10 pm   #22
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Default Re: Ferranti U1003 basket case radio

The Capacitor in the ratio detector circuit will be near the UABC80 valve, under the chassis, very easy to replace.
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Old 10th Mar 2019, 4:52 pm   #23
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Default Re: Ferranti U1003 basket case radio

Just a reminder that the cap. in question, 2.2 or 4uf from memory, is wired with it's positive terminal to chassis.
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Old 10th Mar 2019, 9:36 pm   #24
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Default Re: Ferranti U1003 basket case radio

As indeed is often the case with FM detectors. You'd want 25V too, I think. The voltage is rather higher than AM, usually there is an attenuator switched in on sets with a Magic Eye.
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Old 10th Mar 2019, 9:41 pm   #25
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Default Re: Ferranti U1003 basket case radio

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As indeed is often the case with FM detectors. You'd want 25V too, I think. The voltage is rather higher than AM, usually there is an attenuator switched in on sets with a Magic Eye.
With an outside dipole, well in the attic, I measured 40v across the capacitor on the BBC national stations on one of these radios. The original was I think 150vw, that was possibly what Ekco had in stock, I put in 63vw ones.
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Old 10th Mar 2019, 11:24 pm   #26
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Default Re: Ferranti U1003 basket case radio

That's certainly above average!
It's the electrolytic I've most commonly had to change in valve VHF-FM sets.
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Old 18th Mar 2019, 12:02 am   #27
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Default Re: Ferranti U1003 basket case radio

Just catching up with this one again for an update.

The three capacitors I mentioned have been replaced. C14 is on the end of one of the main HT lines and with only 820 ohms between it and the rectifier, it would be a bit of a pest if it were to become very leaky and could potentially cause the most harm out of these three. C30 being a screen grid de-coupler on a secondary HT line would be a bit of a nuisance if its leakage became excessive and although having another 8.2K resistor in series with it and the rectifier cathode, it would certainly load the circuit and probably eventually send that resistor high in value. Likewise, C31 has 2.2K plus the 820 feeding it and would drag down the voltage and cause problems. The paper capacitors that have been replaced were all Hunts rated at 400 volts and have all had varying voltages of HT across them. All the remaining Hunts paper types are 190 volt rated types and have virtually no voltage across them, so are unlikely to cause any issues with the very slight leakage that they may have.

The mains on/off switch has been bypassed for the time being. One pole, the neutral pole, did recover, and when I rewired the switch so that it would just switch the live only, it became unreliable, so will eventually need dismantling for possible repair or replacement. The chassis hasn’t been removed from the cabinet, but will have to be for this work, also to give everything a thorough clean. I was thinking about repairing the cabinet and filling and staining to colour, but Sam’s suggestion of re-painting/spaying to a colour of choice is going to be what I will eventually do, similar to the Bush in Mark’s Avatar, as seen beside his post on the previous page of this thread – I’ll have a look at what ‘rattle cans’ I’ve got out in the garage!

The back/bottom has been re-fitted temporarily and the set, just as it is, has been soak tested, standing on top of a gramophone in the corner of the main room for the last week, having been on all day and sometimes into the early hours, and has basically performed well. One issue that showed up after a day or so was a rasping noise dependent on volume level which was bad pin connections on the UCC85 VHF tuner valve, so a bit better pin cleaning was necessary. Another slight fault that was noticed while still on the bench was a lot of intermittent crackling on AM medium and long wave only. The UCH81 has dodgy internal electrode connections or debris floating around somewhere. However, after removing it from the set and giving it a few gentle and not so gentle ‘slaps’ while turning, on the workbench top, the fault has been cleared for the moment, although another valve may eventually be needed if the set were to be used on AM a lot – FM being unaffected.

I did replace the ratio detector capacitor as it was a bit low. The original was 4uf at 200 volts working. I didn’t detect a lot of difference if I’m honest and there is a slight distortion on FM audio which isn’t present on AM. This distortion isn’t bad, but is noticeable, particularly on strong stations. I did play around with the value of the capacitor but to no avail. I suspect either slight misalignment or possibly one of the diode sections in the UABC80 is down – I’ll do some more checks around this section when I get the set back on the bench. The set has virtually no drift on warm up, unlike some other sets.

So, would I recommend this model set? Yes, most certainly, but perhaps best avoid one with a broken cabinet if possible. I always think the name “Ferranti” has a bit of a vintage ‘ring’ to it.

Is this set better than a Bush DAC90/A variant? Yes, it’s got VHF/FM to start with, it runs cool, it has good clear audio as designed, and is also easy to work on – not that the Bush isn’t. It obviously doesn’t have the traditional Bush looks with the attractive looking dial/scale, but to me, anything that’s AM only is a bit of a non-starter these days, regardless of the ‘faff’ with pantry transmitters etc., and I try to avoid ‘finding’ them unless they’re something ‘special’.

A comparison with a Bush VHF 61, which I have an example of – the Bush is a nice radio and is mains isolated with a proper transformer, which arguably makes it heavier. However, the Bush is a bit of a ‘drifter’ on first warm up, not dreadfully so, but drifts all the same, which the Ferranti doesn’t particularly do.

More to do to this set, but that’s the story so far.
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Old 18th Mar 2019, 10:03 am   #28
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Default Re: Ferranti U1003 basket case radio

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The set has virtually no drift on warm up, unlike some other sets.
Interesting! Mine drifts A LOT - in the first 6-7 minutes on FM it will drift right off station. After that, it is solid rock steady. Useful info, when I get round to it I will look for any temperature compensation components in the front-end and see if OK (it might be something as weird as the dial cord material being different, and stretching with heat).

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I did replace the ratio detector capacitor as it was a bit low... I didn’t detect a lot of difference if I’m honest
You shouldn't detect any difference - just detect the ratio
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Old 18th Mar 2019, 10:14 am   #29
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Default Re: Ferranti U1003 basket case radio

The U1003 I had did not drift, the U1032 I have, a later but very similar set also doesn’t drift.

Good chassis, another saved to be listened to again.
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Old 21st Mar 2019, 1:01 pm   #30
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Default Re: Ferranti U1003 basket case radio

I'd had a good read of Mark's thread on one of these radios he repaired/restored in the link in his post #10 on the previous page of this thread, and it really was a shame about the dial glass, but also lucky that he had all the pieces of both it, and the broken cabinet.

The dial glass is possibly arguably nicer looking in the Ekco version of this set than the Ferranti version. I had a quick look at the circuit for the Ekco set and as far as I could see it looks identical.

For anyone looking at the manufacturers service information, it's worth noting the later modifications listed, some of which apply to the set in question in this thread, and also in areas of the circuit that have needed attention. The 8uf electrolytic and associated resistor were a manufacturers modification addition in later sets. The ratio detector reservoir was increased from 4uf to 8uf on later sets, but not on mine. There's others that I haven't checked, as I've not had the set opened up again to look.

As for drifting, it's been mentioned that drive cord expansion could be a possible cause. I see that one of the later manufacturers modifications was that the wire part of the drive for the FM tuner was changed to cord. I didn't notice what mine was on this set, but will have a look when I get it back on the bench. Just another thought about drifting is that I was thinking that if a set had been re-aligned with very narrow peaks that it could possibly show up any slight tuner drift a lot more than a set that was a bit out of alignment. This is just a random thought to throw into the mix and I don't have any real evidence to support this theory. The tuner valve in this set doesn't have a 'hat' as in some other sets. The one in mine is a 'special' Mullard type with a faulty double printed label, a bit like a faulty postage stamp or coin, so could be highly collectible - perhaps I ought not to be using it and wearing it out and should keep it to one side and replace it with another one - perhaps it's a special non-drift one

I took a picture of it when I was working on the set:-
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Old 21st Mar 2019, 3:04 pm   #31
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Default Re: Ferranti U1003 basket case radio

That's for if someone cleans the valve and rubs one set of markings off
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Old 21st Mar 2019, 3:05 pm   #32
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That's for if someone cleans the valve and rubs one set of markings off
Brilliant! I hadn't thought of that
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