"Mike Gilmour" wrote in message

"Arny Krueger" wrote in message
...
"Jim Lesurf" wrote in message

In article , Patrick Turner
wrote:



And I am only one of maybe 50 repair blokes in a town of 300,000
ppl.

Says something good about the actual reliability of modern
electronic components.

There shouldn't be a single failure of an SS amp in my town in any
given year.

How many commercial valve amp designs can you quote reliability
statistics for that show failure rates of 1:300,000 or less per
working year?

The other half of the story is the genesis of the missile defense
system that I worked on in the Vietnam era. Interesting because it
is still in service today. An apples-to-apples comparison is
possible. When I worked on it, a Hawk system was composed of about
10 major functional units, each barely small enough for highway
travel. It was powered by about 8 45 KW diesel generators. With
full complement of staff it took about 100 men and 35
duce-and-a-half trucks to move. At least 5 of the 10 functional
units had MTBFs on the order of a day or less. Each was tuned and
thoroughly checked several times a day. The rest were only a bit
more reliable. Three of them had about 400 tubes each. Just the
cables required to tie this system together weighed over a ton.

The Hawk missile batteries were only deployed & never actually used
in the Vietnam conflict.

Something about the non-threat posed by the NV Air Force.

Kept personnel busy though.....

You skipped the part where the NVA overran one and sent the parts to Moscow.

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.

.......and it fits into your top pocket now ;-)

No, its still pretty much filling up the tail section of a HumVee. The last
major update cut the minimum height of the antenna down to that of smaller
air transport planes than a C5A.