[Amps] Bad Tubes

[Dennis W0JX]

I tend to agree with Larry on this issue. We are starting to see the end of the supply of
  "good" usuable 4CX800's and are dipping into the dregs, rejects, etc.
   
  I had a chance to speak with W0MOM at the NIDXA conference on September 16 about tube choices. She said that Alpha buys the 4CX800's from Svetlana (SED) in lots of 60 and they are checked by the supplier to meet Alpha specs. If you check the websites at Alpha and QRO, you will see the notice that says they will not honor
  warranties on amplifiers that use tubes not supplied by the amp manufacturer. As 
  tempting as the cheap 4CX800's might be, the Apha price for a matched pair (about
  $395) is a fair price for a set of quality tubes. If you own an amp that uses these, you
  might want to buy a spare set now. Once the supply of surplus "good" GU-74's dries
  up, the price of new ones is going to jump significantly.
   
  As for the GS-35B, it is long out of production and I don't believe that anyone is going
  to make new ones. These too, will become very hard to get in the near future.
   
  I thought it interesting that Alpha would go with the 8877 with the price so high. Molly's response (W0MOM) was that a pair of 3CX800A7's was even more expensive and that the 8877 has a large installed commercial base and would be around for a 
  long time.

 		
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