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Old 16th Jan 2018, 3:01 am   #21
Argus25
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Default Re: Replica PP8 6 Volt Battery (as used in Roberts RT1).

On the topic of batteries for vintage transistor radios, in general, whether they are used directly as AA, C or D cells, 9V ones, or whether these are packed into housings to replicate original batteries, I now always only use zinc-carbon cells.

The reason is that the short circuit currents from Alkaline cells can be fearsome and vaporize wiring and parts if there is a short. Not only that, if alkaline cells leak the electrolyte is extremely destructive to contacts and metalwork, much more so than the electrolyte from a zinc carbon cell.

Also most transistor radios are low current affairs and zinc carbon cells, that powered them originally are totally suited. So while alkaline cells might have a higher capacity and longer life, I don't think these benefits offset the risks of a thermal accident or corrosion issues in vintage transistor radios.
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Old 16th Jan 2018, 5:55 am   #22
Radio Wrangler
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Default Re: Replica PP8 6 Volt Battery (as used in Roberts RT1).

The oak box looks gorgeous. it seems a shame to cover it, but it wouldn't look right in the set.

My biggest mistake in radio equipment for myself was building a tour-de-force ATU involving plenty of machining, large size, an HP cabinet and developing logarithmic forwards and reverse power meters, computed VSWR meter and phase of reflection meter to go in it. It's an unbalanced SPC transmatch circuit. Trouble is, I should have built a balanced ATU.... The more impressive the ATU looks the more stupid I look!

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Old 16th Jan 2018, 10:53 am   #23
Philips210
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Default Re: Replica PP8 6 Volt Battery (as used in Roberts RT1).

Hi

That's a good point Hugo makes about the short circuit current of alkaline cells. I built a PP9 replacement from a couple of exhausted plastic cased PP9s and did use a pack of alkaline AA cells. Why did I use a couple of old PP9s for the case? Well it's difficult getting them apart without some damage so it's possible to get one good case and lid from two batteries. I used Panasonic PP9s for my battery replacement. I was always wary of the danger from a short circuit so included a small inline fuse for protection.

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Old 21st Jan 2018, 12:24 am   #24
Graham G3ZVT
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Default Re: Replica PP8 6 Volt Battery (as used in Roberts RT1).

Quote:
Originally Posted by Radio Wrangler View Post
My biggest mistake in radio equipment for myself was building a tour-de-force ATU involving plenty of machining, large size, an HP cabinet and developing logarithmic forwards and reverse power meters, computed VSWR meter and phase of reflection meter to go in it. It's an unbalanced SPC transmatch circuit. Trouble is, I should have built a balanced ATU.... The more impressive the ATU looks the more stupid I look!
To counter that, here is an end-on view of the coil of my ultra simple balanced ATU in its development croc-clip phase, awaiting some warmer weather for me to erect the new doublet.

If it shows any promise I'll report back.
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Old 22nd Jan 2018, 3:57 pm   #25
David G4EBT
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Default Re: Replica PP8 6 Volt Battery (as used in Roberts RT1).

So, I've now finished making a correctly sized box, resized the artwork to suit and have finished the battery. Four 'C' cells will have much greater capacity than AAs, so no bad thing. A 4 x 'C' cell battery container just fitted within the limitations of the box size, but I had to use Paxolin sheet for the sides of the box, as can be seen in the first pic, which shows the smaller and the correct sized box. The last pic shows the battery in place.

Re the comments about the oak box, the wood has an interesting history, which I can date precisely to 1944, and there's a tenuous connection to radio design, which I'll explain, but I won't mind if the moderators think what follows is irrelevant ramblings that should be axed.

The oak is from the headboard of a 'Utility' bed - part of a bedroom suite.

My wife's grandparents lived in Liverpool, not far from the docks - an area subjected to enemy bombing in WW2. There were many air raid warnings, often false alarms, but the nervous and cautious always heeded the sirens and headed for the air raid shelters just in case. The sirens sound yet again, and in the house was my wife's grandmother, grandfather, aunt and uncle. The women went to the shelter - the men stayed put. The house took a direct hit - nothing and no-one was found. The shelter was damaged and those inside were trapped for two days. My wife's grandmother escaped unscathed - her aunt with a fractured skull.

Her aunt was 36, her grandmother 61. They were re-housed, and given a grant of £29.00 (£1,200 in todays terms when adjusted for inflation) towards furniture, along with a permit to buy. The letter that came with it was terse - no condolences or good wishes for the future. It's not always appreciated that not only was 'Utility' the only furniture that you could buy, you needed to apply for a permit to justify buying it. Priority was given to those re-housed due to bombing, and to those setting up home for the first time. Anyone else had to rely on secondhand furniture, which as a consequence went up in value.

By 1941 the combination of a severe lack of timber suitable for furniture making and the increased demand for new furniture due to the losses of housing caused by bombing, and to the continuing establishment of new households after marriage, had created a severe furniture shortage. As with clothing, furniture became a 'Controlled Commodity' and carried the 'CC41' stamp, which older forum members will be familiar with.

The Utility Furniture Advisory Committee was set up in 1942, and a key member of the committee was none other than Gordon Russell, who - along with Eden Mills - designed those delightful Murphy 'Arts & Crafts' style radio cabinets from the 1930s to the 1950s. The Committee became the Utility Design Panel in 1943 with Gordon Russell as Chairman. In 1946, in conjunction with the important exhibition of post-war design, "Britain Can Make It", at which radios such as the Bush DAC90 and Ekco A22 were launched.

At the end of the war, the country was awash with surplus electronic components and valves but timber and metal was in short supply, so until the end of 1948, the number of radios, TVs and radiograms that could be produced was restricted by the government, with the emphasis on export rather than the domestic market.

My wife's grandmother went on to live to 103, finished off by a heat wave in 1986. Her aunt revered from her fractured skull, never married and lived to 93. When we cleared the house out, I rescued all of the Utility furniture that had been bought in 1944. Remarkably well made - all of the drawers and carcasses were solid oak. I'm still using the timber for woodworking projects and the little comb-jointed boxes I often make to house home-brew items.

https://en.wikipedia.org/wiki/Utility_furniture

These ramblings are well off topic - I mention them not for further discussion, only for interest due to the tenuous connection to the design aspects of Utility Furniture, relevant to Murphy cabinetry which came from the same 'design stable' led by Gordon Russell, and the shortage of timber, which continued to affect radio manufacturers in the post-war years.

I guess that rounds the thread off. Thanks to everyone who has contributed with advice and encouragement.

Hope it's of interest.
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Old 28th Jan 2018, 5:31 pm   #26
'LIVEWIRE?'
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Default Re: Replica PP8 6 Volt Battery (as used in Roberts RT1).

I still have two items of Utility Furniture which belonged to my late Father & Mother - a Dressing Table and Chest of Drawers.
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