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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 18th Feb 2018, 2:18 am   #1
Alf
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Default 12.6v heater version of 6V6/6BW6

For some time I've been wondering if there was a 12.6v version of the ubiquitous 6BW6/9BW6/6V6 valve, and it seems that there is, the 12CM6 (also 6CM6 6.3v)
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Old 18th Feb 2018, 3:30 am   #2
usradcoll1
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Default Re: 12.6v heater version of 6V6/6BW6

The 12V6GT was designed for the new 12V GM cars starting in the 1953 model year. They were used all the way to 1958 in some GM radios, both single ended and push-pull.
Around the mid to later 50's, all car radio manufacturers were starting to switch to Space-charged valves, 12V anodes and screens, thus eliminating the HT power source and using a high power type transistor.
The only counterpart valve of the 6CM6 that I know of is the 12AB5, which is the 12V version of the 6CM6. Motorola used them in their first 12V car radios.
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Old 18th Feb 2018, 3:31 am   #3
Synchrodyne
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Default Re: 12.6v heater version of 6V6/6BW6

There were also the 12V6GT and 12AQ5, introduced 1952-53 for use in 12-volt car radios. Many 12-volt applications were already covered, as most of the 150 mA AC-DC series-string small-signal valves happened to have 12.6-volt heaters. But there were some gaps that needed to be infilled with new 12.6-volt issues as the American car industry swung from 6-volt to 12-volt electrical systems.


Cheers,

Last edited by Synchrodyne; 18th Feb 2018 at 3:32 am. Reason: Crossed with USRadColl1's post.
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Old 18th Feb 2018, 10:46 am   #4
John M0GLN
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Default Re: 12.6v heater version of 6V6/6BW6

Obviously not the same as the 6V6 and 12V6 mentioned in the previous posts, but it had me puzzled for a while when looking at the schematic of a RCA Victor AA5 set and the output was a 50L6, what on earth made them use a 50V version of a 6L6 in a such a small wireless, a bit of delving into my valve data book revealed that the 25, 35 and 50L6 were not the same as the 6L6 with different heater voltages.

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Old 18th Feb 2018, 11:35 am   #5
turretslug
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Default Re: 12.6v heater version of 6V6/6BW6

I think that the US setmakers generally had the quandary that HT derived directly from their mains made it difficult to get respectable output power (or good advertising copy, anyway....) with valves that were comparable with the 6V6, so the xxL6 variants needed to be called on with their greater heating power and emissive area to drive a greater current swing through the output transformer primary. This trend is also quite noticeable with US shipboard communications receivers that had to cater for 110VDC supplies where something like a 25L6 might be fitted, yet only yielding 1-1.5W audio power.
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Old 18th Feb 2018, 12:08 pm   #6
vidjoman
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Default Re: 12.6v heater version of 6V6/6BW6

There was a 25V6 as well. I used it in equipment built as an apprentice back in 1957.
Don’t forget the valves we are talking about have American origins and the heaters would have been created at different voltages/currents to suit series heater chains operated directly from 110 volts.
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Old 18th Feb 2018, 3:00 pm   #7
paulsherwin
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Default Re: 12.6v heater version of 6V6/6BW6

Yes, the 50L6 was popular in American sets because it allowed the construction of AA5s without a dropper resistor. There were fewer benefits for 220/240V sets.
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Old 18th Feb 2018, 7:28 pm   #8
G8HQP Dave
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Default Re: 12.6v heater version of 6V6/6BW6

I believe I have one or two 19BW6, the 150mA version.
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Old 18th Feb 2018, 7:42 pm   #9
G6Tanuki
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Default Re: 12.6v heater version of 6V6/6BW6

What about the 12A6?

http://www.r-type.org/exhib/aaa0599.htm

Used extensively in US WWII gear such as the 'TCS8/12'-series of receivers [which as well as using a 12A6 as the output-valve use another one as the receiver local-oscillator!]
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