That sounds horrible! The wonderful thing about those amps is that there
are enormous safety margins on everything and they are just solidly
over-engineered. Why would anyone want to wreck that for the sake of
less than one S-unit?
--scott


Scott,

the Collins 30L-1 has safety margins on everything but the final tubes,
which can get easily damaged when the amplifier is tuned up by an
unexperienced operator. It is a common experience to open a 30L-1 and see
holes in the tubes plate. The 811s do not at all forgive operator mistakes.

Moreover, with only 260W available total dissipation, one must be very
careful also during normal operation, especially on CW. In my opinion using
the carbon-plate 572B in place of 811s is a must. Same output power, but
with 640W total dissipation.

Coming back to the "upgrade kits", I hate modifying any vintage equipment.
My philosophy is that, if I need something better or more powerful, I get
something else rather than modifying what I have.

Although I would never substitute the doubler with a tripler in my 30L-1
power supply, I must admit that it may not be a bad solution provided that:

- the 811s are replaced by 572Bs
- the amplifier is never pushed to a higher output power than before the
modification (that is about 650W), so that the power transformer and the RF
circuitry do not get stressed.

With the higher voltage produced by the tripler, a lower plate current would
result for a given output power, with advantages in terms of driving power
and linearity.

73

Tony I0JX
Rome, Italy