[R-390] RF IMD Problem SOLVED!

[Veenstra, Lester B.]

Yes, I have long maintained that the only valid tube tester is the =
receiver (R-390 or R-1230) it's self. Swapping around a set of "good =
spares" frequently shows which are critical in one location, and in =
another location, there is no difference in function between any of =
them.=20

Another phenominon of such a swapping exercise is that pulling the =
inservice tube out and swapping in from the "good spares" set wuill show =
and improvement, and then double checking with the orginal tube will =
show the same improvement. At that point it is time to reach for the =
De-Oxit.
    Les (K1YCM/3)


-----Original Message-----
...............
What I DON'T understand is this.  These two tubes checked IDENTICALLY in
the B& K emission tester, both checked IDENTICALLY for gain in my
receiver at 21MHz.=20
YOUR THOUGHTS ???