[R-390] microphonic 5749W

[Scott Bauer]

FYI, I have been using 5749W's made by Phillips on a
1986 contract. I have 100+ and am having micro-phonic problems
with them in the PTO and a couple spots on the R-390A IF strip.
They work fine for the first 20 or 30 hours then go micro-phonic.
These are the tubes with Phillips written in blue ink.
If you should see these at a hamfest, don't buy them.

 Scott W3CV