> Yes, I am keying via the cathodes. > > I did measure across R74 as you recommend, and my measurements were about > the same. The value of R64 is 15.9K; up a bit but not enough to account > for what I'm seeing. > > I'm going to see if I have any spare tubes to swap tonight. > > Mark K3MSB Great, and 15.9K is still well within 10% tolerance. 73 de Neil ZL1ANM