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 Post subject: Re: BK 650/675 Mutual Conductance
PostPosted: Oct Mon 26, 2020 7:23 pm 
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Location: Mesa, AZ 85206
Thanks, Bob..you are one of the people WAY smarter than me here.

You (and others) have correctly pointed out that testers are not the be all and end all, and may well be somewhat over-valued for the practical technician.

I just found it interesting first hand that a tube tested on one unit (the BKs having only one light for all designed shorts...) can lead you to think a tube is unacceptable, but another unit with different testing sensitivites may read it as fine.

I find this as a known drawback to the BK testers that one can't separate H-K leakage from a dead short between other elements.

Steve


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 Post subject: Re: BK 650/675 Mutual Conductance
PostPosted: Oct Tue 27, 2020 10:11 pm 
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Joined: Jun Sat 15, 2019 7:43 pm
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All tubes have some heater to cathode leakage, power tubes will have more.
viewtopic.php?f=8&t=81699

DM


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 Post subject: Re: BK 650/675 Mutual Conductance
PostPosted: Oct Wed 28, 2020 1:10 am 
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Location: Mesa, AZ 85206
Tis was a very interesting read! Thanks!

Later jukebox amps use 6973s, and has been noted before, many test shorted. I pulled out 4 of my identified shorted 6973s and they were all testing as shorted due to excessive H-K leakage. I have not seen a data sheet that specifies maximum HK leakage allowable.

While, generally I recommend to folks getting an amp restoration to get new 6973s (to the tune of an extra $100...), It only is an issue because I have a fistful of them to have have to test for a working shorts light...

Steve


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 Post subject: Re: BK 650/675 Mutual Conductance
PostPosted: Oct Wed 28, 2020 1:19 am 
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Joined: Mar Sun 20, 2016 11:04 pm
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Location: Mesa, AZ 85206
found this thread....https://www.antiqueradios.com/forums/vi ... 913...kind answers my question...


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