Increasing life of tube by reducing cathode current - will it work?

[PRR]

> GE  5 star tubes are supposed to be good for 10,000 hours, no?

The tubes he cites appear to be in the ECC199 family. The '199 data gives >5,000 hours AT conditions similar to his (12-15mA).

So something isn't right.

> Sky King, Twighlight Zone, then the test pattern...

OTOH, we observed anecdotally that if you left the TV on after the transmitter was shut-down, regularly, the Tuner tube would fade or crap-out. The theory was that it was idle-biased at 10-20mA for lowest snow on weak stations, but the makers knew people didn't watch weak stations much. When a usable signal was received, the AGC would throw the tuner current down to 5mA, 2mA, whatever was needed. And that non-pro TV sets were value-engineered with this pattern in mind.

You forgot the Sermonette.

 

[CJ]

of course we have a site for this,

http://www.tv-signoffs.com/signoffs_A-E.htm

 

[PRR]

> tube life is about 20 hours before emission starts to drop on the tube.

Remarkable echo on Broskie -- link, go about 1/6 down the page.

A friend once complained to me that his recently purchased NOS and super-expensive tubes stank, as they quickly, with as little as six hours of use, lost transconductance. I took his box filled with super-expensive "bad" tubes home with me, so I could test them with my mutual-conductance (gm) meter. They all passed, which made sense as they were all NOS tubes from great European tube manufactures, such as Mullard, Philips, Seimens, and Telefunken. I returned the box, which cost him about $500 then and today would be worth closer to $2,000, with the good news that they were all "good" tubes and with the observation that whatever problem his system was suffering from "bad" tubes were not the cause. A few months later I asked him what he had done with the box of tubes. He had, of course, thrown it away; what else would you do with "bad" tubes?

 

[ruffrecords]

I loved this bit:

'Since there are more than 200 classified forms of mental illness, it's a wonder that audiophilia has not been added to the list.'

Cheers

Ian