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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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 Post subject: Re: Non-metal Chassis
PostPosted: 17 Jun 2014, 15:44 

Joined: 17 Jun 2014, 14:49
Posts: 11
My first one tube radio, a regenerative AM broadcast receiver, used a chassis/panel made from 1x2's and tempered Masonite.
One solid Masonite for the front panel, and two strips, with a tube socket mounted between them.
I forget what tube I used, but had battery for B+ and used a light bulb in series with the filament, running off the AC main.
it worked quite well, with one oddity. the light would flash off and on.
I knew less back then, was just learning, and now I know what was happening
The filament was opening up and closing, causing the light to "flash", LOL
I think I first ran it with battery for the filament.
Shielding was not a problem, but as you progress, shielding becomes a problem. Now I would add foil as shielding, using maybe epoxy to hold it in place.
Beware plastics, especially when heat is involved. I saw many cheap plastic cased am radios with the plastic melting from the heat the tubes gave off. Some had heavy foil, sometimes on what may have been asbestos, to shield the plastics from the heat.

Wayne WA2YNE

 Post subject: Re: Non-metal Chassis
PostPosted: 28 Jun 2014, 01:04 

Joined: 09 Oct 2012, 19:43
Posts: 363
Location: Vancouver Canada
This is the last wood build i finished. Walnut and Maple. No internal shielding and only a copper plate for the bottom just because a friend had it left over from a piece of art he was making. The tubes dissipate a lot of heat sideways so that should be made note of, but, i kept the cab small (6"x8"x2.5" outside). From the inside of the cab the resistors and possibly the rec-diodes are the only real source of heat so i arrange components such that air can flow easily threw the maze from holes in the bottom back of cab and out threw the top air screens. This amp however has low gain so shielding is not a biggy as long as it is not sitting too close to a hum field producer. High gain cct's are another story all together though. Have a look at Bruce's thread on his phono pre-amp achieving -90db of silence. Even with shielding, an amassing and very impressive figure.
Just don't take your amp in the tube with you.
I love wood to.

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