Hi,

This amp would +not+ be a good candidate to change
to Russian high power triodes:
The Galaxy power supply HV is only about 1000VDC,
and the linear's output tank circuit uses a "trick" circuit
to compensate for the high output capacitance
of the ten paralleled sweep tubes.

They used to say that the key for economical operation
was to change out all ten tubes for a matched set,
once the output dropped to an unacceptable level.
If you just substitute one or two new tubes at a time,
for the weakest ones, the new tubes beat themselves
to death in a hurry, trying to carry a lot of the load.
WRL used to sell matched sets of 10 tubes for around $30
when the amp was still being produced. $30 is now about
the price of +one+ 6LB6 on the audiophile market.

One interesting feature of the amp is the way the operating bias
is made to shift more toward class A if the rf output voltage envelope
departs from being linearly proportional to the input rf
voltage envelope. I never owned one of these amps,
so I don't know how well that worked in practice.

73,
Ed Knobloch


gb wrote:

Since this unit uses ten (10) - 6LB6 sweep tubes it is not a practical
amplifier -- since these TV sweep tubes are no longer produced. Might be a
nice project to convert it to a couple of Russian triodes. I would sell the
tubes for the $$

gb