Civilian Wartime Radio - Further Notes

[Sparks]

I have started this thread again as Civilian Wartime Receiver Further Notes because the original thread had wandered so far off track, it was difficult to separate what was being talked about.
Here is the cabinet as purchased.   It doesn't have any major scratches, and I am confident that I can improve it quite a lot.  
The 4,700pF capacitor from the top right of the chassis has now been re-positioned underneath.
The original on/off volume, a 1M pot had a faulty switch, so I replaced it with a 500K pot, as I hadn't got a 1M one.    As an experiment, I replaced it with a 1M pot (without a switch) to see how it performed.    There was no appreciable difference, so I put to 500K one back until such a time as I can find one with the correct value.  
I also took the germanium diode out and put the Westector back.   No difference in performance, so the Westector remains in the circuit.
When I first purchased this set, I had it in mind to sell it after it had been restored.   But I have become so attached to it, that I have decided to keep it.    I intend to continue in my efforts to improve it some more, and may even invest in a new ECH35 and EF39, as the present ones look rather scruffy.
Bob
           

[boater sam]

The EF39 looks very good compared with most, they tend to lose the red coating more than any other in the series I have found.
You could simply repaint it as it works OK, many don't work well when the coating becomes disconnected from pin 1.

[Sparks]

Yes, As I said in the first part, initially it was completely unstable, until I connected the metalising pin to earth, and then it was OK. I could re-spray it, but it may still look a bit rough, and would also lose its Mullard markings. New ECH35 and EF39s are available on Ebay for less than £5 each, but are straight-sided military ones painted silver - not as good looking as the red ones with the shoulder. I have some further ideas on this that I will try out soon.
Bob

[Crackle]

I believe the original valves in these receivers were only marked with a BVA number.
Mike

[Murphyv310]

Hi Mike.
That's correct, my set had a full set of BVA marked valves and another restore set had the ECH35 Marked with the BVA designation. I may have a couple in my stock come to think of it.

[Murphyv310]

It's good to see another set saved and fully cleaned up. The use of two transformers may seem odd but if that's all you have then why not. I have a Radiospares universal mains transformer that most likely would fit and do the job too, I've used another in a project and it is good in a radio.
I have to say these sets work well for a short superhet and your radio should be fit for many more years use, let's hope medium wave keeps alive for a long time.

[Sparks]

I have now rubbed down the cabinet and sprayed it with clear lacquer, and it came up quite well.    I have placed the chassis back inside it.    All I need to do now is shorten the speaker lead, and put a proper plug on it.    Also make a new back.     The distortion on one very local station seems to occur when connected to an outside aerial.    When is is only on two or three feet of wire, it is OK.     Despite its age, the condition of the cabinet is still very acceptabvle.    The new speaker grill is a place mat that I got from Wilkisons store.   It is ideal being a loose weave.   It cost about £1.15 and is the only item I purchased for the set.
Bob
   

[ppppenguin]

I suspect that the original manufacturers used any speaker cloth they had to hand so who's to say that a mat from Wilkos is wrong.

[Murphyv310]

Nice result indeed, grey is a good neutral colour that suits any radio.
Great result and top marks from me.

[boater sam]

Used place mats for speaker frets for many years, some of the patterned ones look very 'period'.

Your distortion sounds like the AVC is not working, have you checked the AVC decoupling capacitor? It is likely to be leaking badly or short circuit.