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- Mar 10, 2013
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Wow, that is a STEAL of a price! I paid $550 for mine and that was considered cheap for 4.1mW N.O.S. condition.
As UK states you can almost always coax red out of just about any tube given the right mirrors, but to get orange is a feat. It certainly can be done though. I discussed this with Dr. Sam after I got mine and more often than not you need to be able to access and align an external mirror to the Anode (HR) end.
It just depends on the way that the tube was constructed. On Melles tubes, the HR mirror is passing the red to allow the other colors to resonate. On some tubes both mirrors pass red. The bore width and length play a part too, as well as the gas fill and pressure. Most other color tubes are filled at a lower pressure than red to maximize gain, at the expense of the tube's life. If you want to do a external mirror work, you'll have to determine how the mirrors have been set up. And I would definitely not encourage taking apart a perfectly good tube. The aluminum cover is there for a reason. If you expose the tube to the air, the stability will go down, as well as it's overall power potentially. It will also be exposed to the environment around and a lot to get dirty, and it will no longer be protected by the rigid housing if it is dropped, etc.
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