Rerurn to Romy the Cat's Site
In the Forum: Melquiades Amplifier
In the Thread: Single-stage Melquiades vs. DHT amps
Post Subject: Make mine thoriated pleasePosted by floobydust on: 1/27/2009
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Yes, there are some specific differences between how various manufacturers burned in their tubes and the initial firing of the tube and flashing the getter, etc. There is an interesting video of the old Blackburn Mullard plant here:
http://www.techtubevalves.com/about_us/film_reels.php
Thoriated filaments must be run at their rated voltage and not lower to ensure full recirculation of the thorium into the tungsten wire (over simplification). There are some sources which have some NOS tubes... The Tube Center and ESRC (basically the same folks) keep a large inventory and are located near Orlando, Florida. The show 10Y tubes at $60.00 and the 801A tubes at $75.00. Personally I would lean towards getting the 801A and using a 7K load, 600V plate supply and -55 volts bias. Good for about 4-watts. A regulated DC filament supply would be best for long life, reliable performance and quiet. Links to the sources:
http://www.thetubecenter.com/
http://www.esrcvacuumtubes.com/
I've not dealt with them yet but am planning a visit there once I get back to the US.... I'd prefer to hand-pick my glass if at all possible.
Regards, KMRerurn to Romy the Cat's Site