Meat Plow wrote:

On Wed, 11 Nov 2009 14:01:33 -0500, "Michael A. Terrell"
wrote:


Meat Plow wrote:

On Tue, 10 Nov 2009 22:46:14 -0500, "Michael A. Terrell"
wrote:


Trevor Wilson wrote:

"Sylvia Else" wrote in message
...

Whatever happened to circuits that just contained a couple of valves?


**There never were any "circuits that just contained a couple of valves".
When they first arrived, TV sets were mindbogglingly complex devices
compared to anything that preceded them (in domestic appliance-speak). They
were also fabulously unreliable. You could figure that the average TV set
would require several repair jobs every year. Your incredibly complex, LSI
controlled, TV set is likely to be vastly more reliable. You've probably
found the first fault it has ever had.


It sounds like they only sold crap in Australia, and that you've
never seen the very low parts count in a Muntz TV.

My parents had three service calls in 15 years. Two of those were
due to lightning taking out the front end in the VHF tuner. The third
was a bad electrolytic in a voltage doubler that took out a fusible
resistor. That isn't a couple times a year.

My dad always bought RCA even though the RCA tube guy seemed to visit
monthly. (color sets)


I did TV repair for about 20 years, and never saw anything that bad.
Most customers got three or four years out of a new set before the first
service call. By the time a set needed a lot of repairs, it was cheaper
to replace. I went on some calls on Zenith sets that were almost 20
years old, and it was the first service call. The cost of 12 service
calls in one year would be higher than a new TV set.


Only tubes I deal with these days are in guitar amps.


Whoopie. I won't touch tube sets, unless they get a full overhaul.
I no longer work with multiple 65 KW Klystrons, or transmitter tubes
made with beryllium oxide ceramics. Have you ever used a water cooled
power tetrode with two, 1000 A, 1.5 volt filaments? The AC had to match
to a few millivolts, or it would modulate the output current. You had to
use an open ended wrench to adjust the length of a copper buss bar. Its
resistance went up as it was stretched. This was in the RCA TTU-25
series UHF transmitter.

I have seen a TV transmitter, a Doppler radar transmitter and a huge
mercury vapor rectifier. Have seen a walkin klystron but only in
pictures.


Ever seen a klystrode?


--
The movie 'Deliverance' isn't a documentary!