"Jim Lesurf" wrote in message

In article , Arny Krueger
wrote:
"Jim Lesurf" wrote in message

[snip system details]

Today, the fire control system fits on the back of a Humvee which
also powers it. It has about 5 times the range. None of the
equipment is routinely maintained in the same sense. Components
basically run until they break (rare) or are fired, and then they
are replaced.

Really and truely the only difference is solid state technology and
other technological changes that it enabled.

In a parallel vein, when I started developing/using 100-400 GHz
receivers 20-30 years ago for astronomy we used to use Klystrons that
typically lasted about 100 Hours each and cost a few thousand pounds
each, and BWOs that cost loads more and lasted a bit longer. More
recently we just built our own Gunn oscillators, which just run until
we shove them in the cupboard until next needed. :-)

(OK, one died when an MSc student insisted on applying double the
required voltage for long enough to kill the protection circuit, and
then the diode.)

The PSU's for the Gunns are loads cheaper and easier as well. Indeed,
my favourite Gunn PSU is the same design as I used to like for use in
audio preamps. :-)

FWIW My experience with domestic audio is that the main reliability
problems [1] are down to things like switches, contacts, etc. e.g.
essentially 'mechanical' in nature. With electrolytic caps wearing
out as a secondary issue.

[1] Ignoring 'hostile action' by the user. 8-


Yup. The only grasp I get on this tubed amp think is that people are
afllicted with

(1) Excess sentimentality
(2) Desire to fiddle - like vinyl cleaning rituals
(3) Desire for bragging rights - something out of the ordinary even if
backwards