Eddystone 658/670.

[FERNSEH]

This set has well and truly been got at by someone in the distant past. Check out that mains dropper resistor and the PL259 aerial socket, I'm sure those parts are not correct Eddystone components.
For starters I found valves in the IF and audio stages in the wrong positions, some valves were glowing brightly and others not lit up at all.
After refitting the valves in the correct positions I found only two of the four wavebands were working, band 4 246 to 575 metres and band 2 5.8 to 13 Mc/s. Band 3 1.2to 2.75Mc/s was completely silent. Band 1 12.8 to 30Mc/s just produced a hiss and funny noises.
Waveband 3 turned out an easy fix, the aerial input coil had been shorted out for some unknown reason, removing the short circuit brought in the signals.
The IF amplifier was found to be spot on at 450Kc/s so at least no twiddling there.
Wavebands 2,3 and 4 were easy to realign, problems with waveband 1 though. It is possible to trim up the lower frequency end of the band the HF end will not line up properly at all. The reason for that might possibly be that the valve heaters are under run, that mains dropper is the wrong value, it's 600 ohms and according to the service manual it should be 500 ohms. The UCH42 has a 14 volt heater and the voltage measured across pins 1 and 8 is 11.5V. An under run valve may not work at the higher frequencies.
DFWB.

[G6Tanuki]

When fixing-up my much-got-at Eddystone 840A[1] I found that the band-4 oscillator wasn't oscillating: investigation showed that there was a bad solder-joint on the oscillator coil - from what I could see the wire had never been properly de-enamelled before soldering so the only possible area available to be soldered was the cut end of the wire - which had a ball of solder on it totally out-of-contact with the tag to which the oscillator-section of the wavechange switch connected.

This all looked original: I'm suspecting this was a "friday afternoon" radio where getting-it-out-of-the-factory-to-meet-production-quotas was deemed more important than full functionality!

BTW if you suspect your radio's been 'got at' as far as trimmer-twiddling's concerned, you can often identify what the last-best settings (before the Phantom Twiddler arrived) were by the degree of oxidation on the static part of the trimmer-vanes. The leftmost trimmer in the last of your photos shows a really good example of this !!

[1] HT smoothing-choke replaced by a "totem-pole" of wirewound resistors, BY127 diode wired in place of the HT rectifier (which was thankfully still in-place to provide a sane heater-chain). I suspect it'd had a 'that capacitor' failure and the excess current-draw had nixed the choke and cooked the rectifier.

[turretslug]

I get the feeling (and it's entirely feasible that I'm mistaken, as the early 670 isn't something I'm familiar with) that someone has actually sawn through what was originally a one-piece Paxolin rear apron and removed the central section in order to make the co-ax connector mounting plate. That can't have helped the structural rigidity and may even have case-chassis insulation/clearance integrity degradation questions in this potentially live chassis set, which seems really irresponsible. I wonder if the aerial connection is as effectively isolated as the original design required and ensured? What some people do, rather than make up a simple banana plug-BNC (say) adaptor lead for ATU etc. connection purposes..... It's not as if the input arrangement on a set like this possesses great matching/screening integrity anyway.

As for the reason for that shorted coil- well, who knows? At least the set is in thorough, competent and respectful hands now. Those Ux4x series valves are fortunately pretty commonplace and inexpensive.

[FERNSEH]

Originally Posted by turretslug

As for the reason for that shorted coil- well, who knows?

Whatever the reason for inhibiting the 1.2 to 2.75Mc/s band the previous user was quite resolute that nothing could be received on that waveband.
Not only was the aerial coil shorted out but also the link to the aerial socket was cut. Absolutely nothing could be received. Very strange. Is there anything on the waveband we shouldn't listen to?

The set now receives Radio Tyneside on 1575Kc/s. This is a very low power transmitter, only 1watt! It's hardly DX reception as the TX site is only five miles from my location.

DFWB.

[turretslug]

How curious. An overly anxious and controlling parent wishing to defend their offspring from the moral danger of pirate radio?

[FERNSEH]

That could well be the reason. Or perhaps Radio Luxembourg was the proscribed station?

Here in the North-East of England the "local" pirate radio station was Radio 270.
http://www.offshoreradio.co.uk/270.htm

DFWB.

[ms660]

So, no 2.182 then.

Lawrence.

[Radio Wrangler]

1.2MHz excludes radio 1 as well, if the band edges are set accurately. So no pirates, no Luxembourg, no R1. Looking for a common factor suggests loudness, style of music or maybe Savile-avoidance.

David

[ms660]

Long shot from me, maybe to reduce interfering osc radiation on a multi set common antenna installation.

Lawrence.

[Radio Wrangler]

It's not just disabling reception or preventing LO coverage, it also sounds like it was deliberately made hard to undo.

David

[FERNSEH]

Originally Posted by Radio Wrangler

1.2MHz excludes radio 1 as well,

David

That's right, BBC Radio 1 was on 247 metres and waveband 3 of the Eddystone covers 110 to 250 meters so the new pop and rock station was also receivable. No reception of that station allowed either.
So it seems many of the stations in that waveband could be considered degenerate and had to be excluded.

DFWB.

[FERNSEH]

The PL259 socket has been replaced by four 4mm sockets. The red sockets are for a balanced aerial feeder and the two black sockets are earth terminals.
The middle socket is for signal earth and the lower is for the cabinet only.
The three fixing screws are 4BA nylon types for added safety.

DFWB.