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 NEW  Matt presents bias and operation data for the 6V6 tube in SE operation - 6V6 Single-Ended (SE) Ultra Linear (UL) Bias Optimization.

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PostPosted: 25 Jan 2018, 09:53 
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Joined: 26 May 2009, 18:51
Posts: 129
Location: Lilburn, Georgia USA
I have had this Magnavox model 88-02-00 console tube amp for years and am now getting around to it. It is a stereo push pull 6V6 with 6EU7 driver tubes. It has a 6CA4 9 pin rectifier tube. I recently acquired a Sams Photofact schematic and parts folder for it .Last night I tested the tubes on the amplifier with my Knight 600 tube tester that my father built back in the 1960s. 3 of the 6V6s tested 80% and one tested 60%. The 6EU7s are not on the list on this tube tester nor the 6CA4 rectifier. I have another Knight 600 tester that has either an older or newer tube scroll list in it. I will have to dig it out of my store room. I also have all the new capacitors and most of the resistors. Last night on Ebay I ordered 2 slightly different from each other AM-FM tuners that use this amp-power supply. I intend to electrically restore these and have a tube FM stereo setup.


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PostPosted: 25 Jan 2018, 14:03 
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Joined: 08 Aug 2009, 03:11
Posts: 2229
Location: Chilliwack, BC
If it works, it works, tester not needed in most cases ;)

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* Ratings are for transistors - tubes have guidelines*
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PostPosted: 28 Jan 2018, 08:28 
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Joined: 01 Jun 2013, 09:05
Posts: 677
Geek wrote:
If it works, it works, tester not needed in most cases ;)


+1,

If it sounds good use it. A balanced pair can be a bit different but its OK to test the equipment but if you like the amp change tubes.
The biggest problem with old equipment is cathode cap leakage driving the output tubes into heavy bias current.
Or grid caps leakage.
The other is tube rectifiers failing.

Regards
M. Gregg

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