5b3 6v6 current

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tubeswell
Posts: 2337
Joined: Thu Mar 27, 2008 6:42 am
Location: Wellington. NZ

Re: 5b3 6v6 current

Post by tubeswell »

kgreene wrote:I'm still a bit mystified about that amount of idle current. Will the 6v6's tolerate that?
What billc and gingertube said already.

The cathode resistor voltage gives a more accurate indication of current than your bias probe. Voltage/resistance = current, and if you know that exact DC voltage and the exact DC resistance, then you can calculate the exact tube current total for both tubes and divide that by two to get each tube. Assume about 2mA screen current for each 6V6, so thats

[20V/270R]/2=.037A tube current

minus 0.002A = 0.035A plate current

0.035A x 350V = 12.2W plate dissipation
He who dies with the most tubes... wins
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Stevem
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Re: 5b3 6v6 current

Post by Stevem »

To check power supply ripple voltage just set your voltmeter for low ac volts!
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Not screaming like the passengers in his car!

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labb
Posts: 223
Joined: Sat Aug 02, 2008 2:03 am

Re: 5b3 6v6 current

Post by labb »

Another source of hum to check is the on/off switch being part of the volume pot. I have built a couple of the 5B3 amps and I always got hum if I tried to use the switch as part of the pot set up. Had to change them out in both amps to get rid of the hum.
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