[Amps] Input Impedance of GG vs B+

[Kimberly Elmore]

I'm curious about how input impedance of a GG am changes as a function of B+ supply. I have a single 3-500Z GG amp for which I can't seem to get as good a match as I expected when adjusting the input networks. It's runs about 4 kV (3.6 kV under load) B+ and and uses the AL-80A input network. Should I expect the input impedance of a GG amp to vary significantly as a function of B+ supply?

Kim Elmore, N5OP