Linear Amp Project HF VHF UHF Amplifier

Posted on Feb 4, 2014

Tube Tester and Filament Burn In Jig - Here`s my answer to cooking the tubes for days and then testing them before inserting them in an amp. Note - I have learned an important lesson with this jig. The filament alone heats the entire bottom of this tube and even with the fan blowing air into the box, the bottom of the tube will get too hot to hold

Linear Amp Project HF VHF UHF Amplifier
Click here to download the full size of the above Circuit.

in your hand. This is an important lesson regarding cooling of the tube, particularly the grid ring and filament seals. Do NOT run this tube without air, lots of air, blowing around its base and through the anode cooler. There is 38 watts of heat from the filament alone. W4ZT GS-35B Tubes Glow In The Dark! - Pictures of GS-35Bs glowing in the dark producing a rainbow of color. Do yours glow My bet is that they do. What color are they Want to share your pictures NOTE: Do NOT use a center tap filament transformer. To do so leads to unbalanced currents in the filament choke and hum modulation of the RF output. Instead, use a separate cathode choke. Note that the filament choke can be made with two 48" long pieces of #18 wire bifilar wound to fit on a 3. 5" length of 3/8" ferrite rod. The cathode choke can be one 48" length of #18 wire on a 1. 5" length of 3/8" ferrite rod. Both chokes are about 25 to 30 uH. Be careful to wind the chokes on a metal rod slightly smaller than the ferrite and then move them to the ferrite rod to prevent breaking the ferrite. Was at this address but Chuck changed his ISP to MSN. MSN wants you to sign up to view his pages so they are no longer available by direct link. You can still view this page by using the Wayback Machine at which will take you here: Chuck`s program was here but now can only be seen by using the Wayback Machine at which will take you here: AG6K - Rich has lots of amp building...

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