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 Post subject: 6v6 vs 6k6 how do they compaire?
PostPosted: Dec Tue 02, 2008 2:52 pm 
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Location: Sandwich, IL, USA
Or rather are they interchangeable of could
you sub a 6k6 for a 6v6 in a 6v auto radio?
Denny Graham
Sandwich, IL


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 Post subject:
PostPosted: Dec Tue 02, 2008 4:21 pm 
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It would work, the 6K6 will have slightly less output than a 6V6, but you probably could not tell the difference in an auto radio.

Try it and see what you think.

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 Post subject:
PostPosted: Dec Tue 02, 2008 4:27 pm 
Silent Key

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The 6V6 is a beam power pentode. The 6K6 is simply a power pentode. The 6K6 takes .4 ampere on the filament, whereas the 6V6 takes .45 ampere. The 6V6 is capable of more power output and greater plate dissipation, 14 watts versus 8.5 watts for the 6K6.

For a car radio that uses a single tube in single ended output, you could most likely get along with either tube, provided it is a six volt set with the filaments in parallel. For a push-pull output, both tubes need to be the same, regardless of type chosen.

I don't think it really is an issue, however, as both tube types are very commonly available.
Curt

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 Post subject:
PostPosted: Dec Tue 02, 2008 4:42 pm 
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Most substitution guides I've seen lists it as a replacement, but the 6K6 needs more bias voltage(18 vs 12v for the 6V6)... Assuming it's cathode biased, I'd check bias and increase the value of the cathode resistor if necessary... Especially if it was going to be a permanent replacement..

Tom


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 Post subject:
PostPosted: Dec Tue 02, 2008 5:15 pm 
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I've replaced a 6K6 with a 6V6 many times and have never had a problem. As long as the circuit has parallel filaments, I don't think you'll notice any difference. Harry


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 Post subject:
PostPosted: Dec Tue 02, 2008 5:25 pm 
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The 6V6 has higher gain than a 6K6. Going back and forth between tubes you will notice a difference.

6V6 can directly replace a 6K6. Due to bias differences, as Tom mentioned, not a good idea to replace a 6V6 with 6K6. Higher negative grid bias is ok but not enough a tube will draw more current.

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 Post subject:
PostPosted: Dec Wed 03, 2008 5:53 am 
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That’s good news guys, thanks. Reason for asking was the difference in cost. $3-$4 for a 6K6 vs. $20 on up for a 6V6.
Can’t see putting a tube in that is worth more than the radio itself. In this case it’s just a late 40’s 6v under dash Coronado radio.
Denny Graham
Sandwich, IL


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 Post subject:
PostPosted: Dec Wed 03, 2008 7:26 am 
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one day while testing various substitute audio output tubes in a parallel 6 volt filament set.. I tried a 6L6 swap for a 6F6.. then a 6K6.. and then tried a 6v6 and all seemed to work in a pinch.. even the 12volt versions of these tubes work alright in a 6 volt socket and perform ok too... as long as it's not a series fed heater chain.

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 Post subject:
PostPosted: Dec Wed 03, 2008 1:22 pm 
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Pbpix wrote:
all seemed to work in a pinch..


In a pinch a 6U6, 6EZ5, 6EY6 or 7EY6, can be used for any of the other 6v 7AC/7S based tubes... In a major crisis a 6DG6, 6W6 or 6Y6 can be used, but those have 1.2A heaters so the power transformer likely will be overloaded in a AC set...

I ran a RCA that uses a 6V6 for a couple days on a 7EY6, and really couldn't tell a difference...

Hey Den, if you don't mind adding a current limiting resistor to the heater line, I'd think 5V6s would be cheap...

Tom


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 Post subject:
PostPosted: Dec Wed 03, 2008 2:55 pm 
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RCA has a section in some tube manuals listing by basing. RC-28 has this section. 7S is a pentode tube. 7AC is a beam tube. Both are usually interchangeable.

Although they can be interchanged watch for voltage and current. Using a 6Y6, as example, filament and plate current will be much higher. Max voltage ratings are much less for this tube and a few of the others. If a 6Y6 screen has very high voltage it will glow red.

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 Post subject:
PostPosted: Dec Wed 03, 2008 5:40 pm 
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Nope Tom, this one only has to look original on the outside, I’ll keep that in mind and slip a note in side if I should happen to change any of the circuits.
Thanks Norm, I think for right now I just might want to sub a 6K6 in this one but I will also keep that in the reference file.
Thanks guys,
Denny Graham
Sandwich, IL


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 Post subject:
PostPosted: Dec Wed 03, 2008 7:07 pm 
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Denny, you looking for a 6V6 metal tube? I think I have several NOS. I could send you a pair or whatever.

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 Post subject:
PostPosted: Dec Wed 03, 2008 7:22 pm 
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Looks like Don has a deal for you, but FYI... In a car radio that powers the tubes by DC, a couple 1N4007s in series would drop the voltage so a 5V6 could be used...

Tom


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 Post subject:
PostPosted: Dec Wed 03, 2008 8:42 pm 
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OUCH, $20 on a 6V6? Hope that is for NOS. I have a bunch of used ones to see me through luckily. Also have a lot of 6K6s. Never tried one in a car radio.


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 Post subject:
PostPosted: Dec Thu 04, 2008 4:42 pm 
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PM'ed ya Don, tks.
Denny G


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 Post subject:
PostPosted: Dec Fri 05, 2008 7:56 am 
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Location: British Columbia
Denny Graham wrote:
That’s good news guys, thanks. Reason for asking was the difference in cost. $3-$4 for a 6K6 vs. $20 on up for a 6V6.
Can’t see putting a tube in that is worth more than the radio itself. In this case it’s just a late 40’s 6v under dash Coronado radio.
Denny Graham
Sandwich, IL


It shouldn't be that difficult to get a hold of a used 6V6. millions were used in TV sets as well as in radios, put an add in the classifieds, someone should have one. Even among new ones the Russian versions seem to be quite reasonable, the radio won't know the difference. $20 each sounds like an AES price for a NOS American 6V6, there are other tube dealers out there.
Best Regards
Arran


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 Post subject:
PostPosted: Dec Fri 05, 2008 8:18 am 
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In September I answered a local craigslist ad for free pickup of a Philco console. Turned out to be a 1953 C 1758 AM/FM with phono.. Anyhow salvaged same which had, among it's 14 tubes, (2) 6V6 and (1) ST 5U4.


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 Post subject:
PostPosted: Dec Fri 05, 2008 8:21 am 
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The Midwest SS-18 I have has 4 6V6 - that'd be a bummer to replace all 4 - luckily they all tested strong. I'm replacing all the other tubes with NOS, though (I've had troubles with it, and once it's halfway working again, I don't want to have to fool with it for a long time).


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