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 Post subject: 6V6 vs 6L6 vs 6F6
PostPosted: Dec Fri 06, 2013 6:38 pm 
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Joined: Sep Sun 01, 2013 12:16 am
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Location: CT 06033, USA
Hi,

What are the differences between these tubes in characteristics and construction?

What are the positives and benifits of each? Which situation is best suited for each tube?

Paul


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 Post subject: Re: 6V6 vs 6L6 vs 6F6
PostPosted: Dec Fri 06, 2013 6:42 pm 
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Paul

Best to compare spec's:

http://frank.pocnet.net/index.html

If you have to pick one I would use 6V6. It has more gain. 6F6 draws more current. 6K6 less. 6K6 and 6F6 are straight pentodes with a 3rd grid. 6V6 has beam forming plates instead of a 3rd grid. All bases are interchangeable but watch for max plate voltages.

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 Post subject: Re: 6V6 vs 6L6 vs 6F6
PostPosted: Dec Sat 07, 2013 4:35 pm 
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Joined: Nov Sat 27, 2010 6:15 pm
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Agree, for most purposes (modest power radios,) the 6V6 or even the odd 6W6 willl do just fine, and has least filament requirements if you are srcounging around. If a 6L6 is spec'd get another one and beware of GA GBc or GC designations. Anyway all of these types are commonly available and reasonably inexpensive, so if you are doing a replacement, best stick with exact replacement.

Use one of the forum sponsors or place a WTB classified for the stuff you need. (I'm not a vendor.)


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 Post subject: Re: 6V6 vs 6L6 vs 6F6
PostPosted: Dec Sat 07, 2013 6:54 pm 
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Joined: Jun Fri 19, 2009 6:34 pm
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Location: Long Island
6L6, 6V6, and 6W6 are beam power tubes; 6L6 and its later variants are used where higher output power is needed; 6V6 and 6W6 for lower power applications (6W6 was designed for more gain on lower B+ voltages as might be encountered in car radios and TV sets with voltage doubler power supplies). 6F6 is a power pentode; 6K6 is the lower-power pentode in the family.

With power pentodes, plate and load resistances are higher, so higher voltage B+ power supplies must be used to obtain significant output powers. Screen grid currents tend to be higher as well, which means more power dissipation (= heat). In general, distortion is higher for power pentodes than for beam power tubes, and load resistance for minimum distortion tends to be higher as well, making suitable output transformers a bit harder to find.

Not for nothing, but when beam power tubes were developed in the late 1930s and early '40s by Marconi-Osram in England and RCA in the US, their higher efficiency and lower distortion (even when triode connected) pretty much ended further development of power pentodes. 6F6's seldom appeared in postwar equipment. 6K6 lingered on a while longer because it made a good vertical deflection amplifier for TV sets when triode connected.

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 Post subject: Re: 6V6 vs 6L6 vs 6F6
PostPosted: Dec Sat 07, 2013 9:50 pm 
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Location: Moline Illinois
I have some consoles from the late 1930's using 6V6 in PP and my 1961 Maggie Concert Grand has 16 6V6 on 2 amps rated 100 watts so they must have been popular with the designers for some reason.

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 Post subject: Re: 6V6 vs 6L6 vs 6F6
PostPosted: Dec Mon 09, 2013 3:42 am 
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Joined: Oct Sat 20, 2007 3:36 am
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Location: Southern NH, 03076
Getting back to the original question, the 6F6 is the older design and is an octal version of the 1932 42.

The 6L6 was the first beam tube released by RCA in March 1936 and the 6V6 in January 1938.

The 6F6 can be considered obsolete and has higher distortion and lower efficiency than the 6V6 which was designed to replace it. In most cases it is a simple plug in swap and worse cas a few component values may need changing to keep it within specs.

The 6L6 is the largest of that early family and later led to some transmitting tube such as the 807 and 6146, all sorts of TV sweep tubes and the 5881, 6L6GC, 6550 and other expensive favorites of the audio crowd. All are 6L6 children.

Carl


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