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General Vintage Technology Discussions For general discussions about vintage radio and other vintage electronics etc. |
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22nd Apr 2019, 8:15 pm | #1 |
Pentode
Join Date: Aug 2005
Location: North Warwickshire, UK.
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Why the use of American valves
Hi team I have a Burndept 290 radio. this model uses American type valves
6L7G-6C5G-6K7G-6Q7G-2/6L6G-SZ4G and a 6G5. Other manufactures also used American valves around the same time i.e Decca-Furguson--Etronic- Kolster Brands-Marconi- Philco-Rap and Sobel. Were these valves cheaper to buy or were they Foisted upon us. Instead of using a typical "FC4" type local oscillator they installed two separate valves instead. When did the Marconi TAX tariff stop per each valve used. Also there does not appear to be many if any equivalent valves to replace these type of valves regards Brian |
22nd Apr 2019, 10:49 pm | #2 |
Dekatron
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Re: Why the use of American valves
Probably cost. Many of these American valves could be had very cheaply after WWII. In some cases substitutes from the more familiar Mullard range could be used....EF39 will work in place of 6K7, EBC33 will work in place of 6Q7 and EL35 or GEC type KT66 will work in place of 6L6...notice these are subs, not equivalents. However it doesn't really matter since most of the American types are still available.
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22nd Apr 2019, 11:30 pm | #3 |
Dekatron
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Re: Why the use of American valves
On a point of detail, genuine KT66s will draw rather more heater current than 6L6s. If the mains transformer is running a bit 'close to the edge' then this may need to be borne in mind.
Cheers, GJ
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24th Apr 2019, 8:21 pm | #4 |
Pentode
Join Date: Aug 2005
Location: North Warwickshire, UK.
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Re: Why the use of American valves
Hi team, well thanks for your input. I cant quite see the argument for a cheaper valve though. The Burndept 290 has 7 valves plus a magic eye valve. What with the cost of adding possibly 2 extra valves plus controlling components and a bigger box to fit them all in I cant see the economics working very well plus the fact that the radio was built before the war(1938) so wasn't restricted to lack of equipment. regards Brian
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24th Apr 2019, 8:43 pm | #5 |
Dekatron
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Re: Why the use of American valves
A lot will have depended on tie-ups/deals between set makers and valve-makers- eg HMV/Marconi/GEC etc used M-OV group valves which were frequently very similar/slightly developed versions of US valve types. The International Octal types, originally mid-thirties RCA, seem to become rapidly adopted and popular even before the obvious boost of WW2. Perhaps Burndept had come to a better deal with a US valve (sorry, toob) importer than they could squeeze from M-OV or Mullard/Philips?
I's interesting/curious that this otherwise straightforward no-RF-stage domestic set uses the 6C5/6L7 combo of separate oscillator and mixer more often associated with pre-war US professional HF receivers (later supplanted by the 6J5/6SA7 pairing in such sets). Many, even expensive and high quality, domestic superhets of the era initially coped with self-oscillating heptodes up to 18MHz, combined triode/hexodes showing their advantage in sets with higher frquency pretension and subsequently becoming near-ubiquitous. |
24th Apr 2019, 8:46 pm | #6 |
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Re: Why the use of American valves
Many of these prewar companies were American owned or had close connections with American companies. KB always designed around American valve types.
There was a completely different postwar phenomenon where lots of wartime lend-lease octal types were dumped onto the surplus market and were used by many small manufacturers. |
24th Apr 2019, 10:53 pm | #7 |
Nonode
Join Date: Sep 2017
Location: Stockport, Cheshire, UK.
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Re: Why the use of American valves
I did read somewhere recently in New Zealand electrical retailers at one time used to have a list of American valves that could replace British originated items.
i'm guessing this was in the 1940s-50s, when it was probably easier to obtain surplus American ones while supplies of British ones had been disrupted.
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25th Apr 2019, 10:05 am | #8 |
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Re: Why the use of American valves
Did New Zealand generally use American valve names (like Australia) or European names?
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25th Apr 2019, 10:23 am | #9 |
Nonode
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Re: Why the use of American valves
My recollection is that both the American and European naming systems were used in NZ, depending upon equipment manufacturer. During the 1960s European names may have been in the majority, but not hugely so. But that is a relatively small-sample empirical assessment. In our household in the early 1960s we had a Columbus radio with the standard E-series valve line-up, and an HMV TV with E-series valves on the main chassis but Mazda-designated valves in the tuner. (As well as the Bush EU24 from the UK with U-series valves and a not-very-good RGD record player, also I think with U-series valves and which I think someone had originally brought in as a private import.) In the mid-1970s when I was in Wellington I had an old S/H TV that had American 6-series valves, including one of those quadrature FM detector types, it might have been a 6DT6.
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25th Apr 2019, 10:39 am | #10 |
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Re: Why the use of American valves
The Australians mostly used American types after WW2. I wonder if this was also influenced by surplus valve availability given the very large US military presence there during the war.
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25th Apr 2019, 5:25 pm | #11 |
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Re: Why the use of American valves
Australians seemed to use American names even when using European types.
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25th Apr 2019, 5:34 pm | #12 |
Pentode
Join Date: Aug 2005
Location: North Warwickshire, UK.
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Re: Why the use of American valves
well thank you all for your responses. Quite interesting and informative as usual. I will get back to listening to " The shipping forecast" (radio 4) on my Burndept 290 with all the original (American) valves still working well. Thanks again, regards Brian
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26th Apr 2019, 8:35 pm | #13 |
Dekatron
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Re: Why the use of American valves
From the 1930s through to the 1960s the BVA [British Valve-manufacturers Association] ran a protectionist 'cartel' - aided by the Government - through which imported valves were subject to serious tariffs - which could easily add 50% to the cost of an 'imported' valve compared to its UK-produced equivalent.
[Strangely - some would argue 'conveniently' - they overlooked the fact that Mullard - one of the largest valve-manufacturers of the time - was largely owned and entirely controlled by the Dutch Philips NV company. It was at one time satirically said that "the only truly British part of a Mullard valve is the vacuum"] US-based manufacturers with a footprint in the UK: Philco, ITT, Kolster-Brandes, FADA, Westinghouse - would at one time supply radios without the valves, but give 'preferential' treatment to their dealers to supply US-manufactured valves to fit in these radios. Done sensibly, this could still be a 'win' for the purchaser, since he/she would have had to pay swingeing Purchase-Tax [up to 40%] on the initial price of radio, but valves [imported] were 'service parts' and so attracted a much lower purchase-tax. |
27th Apr 2019, 11:18 am | #14 |
Heptode
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Re: Why the use of American valves
I've come across both - generally pre 1950's seem to be US but afterwards the Phillips/UK ones seem to hold sway. Surprising given the Aussie preference for US (where we'd have got most of the spares pre airfreight).
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27th Apr 2019, 11:23 am | #15 |
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Re: Why the use of American valves
Brimar valves were used in many sets and were made at the STC/KB factory at Foots Cray near where I use to live.
Peter |
27th Apr 2019, 2:05 pm | #16 | |
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Re: Why the use of American valves
Quote:
I found it interesting that the manual for the Eddystone 640 radio specified the 6k8 or the ECH35 and the 6Q7 or the EBC33 and the 6V6 etc. There is not that much to pick between them all (it might just have been cost and deals) except for the fact the ECH35 is superior to the 6k8, in that it has a higher conversion transconductance. This was explained to me way back in the 1970's by my friend the late John Stokes in NZ, in his radio shop on Dominion Rd Auckland. |
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28th Apr 2019, 6:20 pm | #17 | |
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Re: Why the use of American valves
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28th Apr 2019, 6:24 pm | #18 | |
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Re: Why the use of American valves
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28th Apr 2019, 8:07 pm | #19 |
Dekatron
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Re: Why the use of American valves
I heard that there were many valves that left the factory via holes in the wooden floors that were over the river Cray. They floated downstream and collected by a net some distance away. I lived in Dartford and there were always many Brimar valves around. Usually available in a white box.
Last edited by vidjoman; 28th Apr 2019 at 8:13 pm. |
28th Apr 2019, 8:13 pm | #20 |
Dekatron
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Re: Why the use of American valves
Perhaps I should add that this was during the 50’s/60’s so that’s a long time ago.
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