Rainy day with some TV valves

[G6Tanuki]

Originally Posted by Tubeglow

Some tubes specify pin alignment for heater sag.

I thought that sort of issue was left behind half-a-century back. If it can't fly inverted, or deal with enough "G" to shear the wings from the airframe I don't want to use it.

[Tubeglow]

5Y3 from the data sheet.

Horizontal operation allowed if pins 2 & 4 are in a vertical plane.

Tubeglow.

[k_yller]

"sweep tubes" was designed to working around 16kHz

6P45C from Russian colour TV
up to 90W from pair

[turretslug]

I expect that the directly-heated types with long, thin ribbon cathodes could suffer long-term from gravity's depredations if unsympathetically orientated- the 5Y3 being a prime example. Many who've used the AR88 will know that they can get surprisingly fragile with age.

[G6Tanuki]

Originally Posted by k_yller

"sweep tubes" was designed to working around 16kHz

They happily go way, way beyond that: us radio-amateur types happily run them up to 21MHz (or 28MHz with slightly reduced performance) in grounded-grid service.

You can push a single 6LF6 to 175-watts PEP. It's rated for 40-watts continuous anode dissipation, temporary overload of 200 Watts. I'd say a single PL519 should deliver 150W PEP out without being unduly stressed.

Google "Skinnier Linear" for more details.

[kalee20]

Originally Posted by k_yller

"sweep tubes" was designed to working around 16kHz

Yes- and to achieve the 16kHz prf, the valves had to be designed to be switched on and off in microseconds (at most). Which explains why they work well up to RF, they have low lead inductances etc.

[HamishBoxer]

Keep say how good the PL5 range is and it will become the next PX4 with mega price to match.

[Ed_Dinning]

Probably a good valve for instrument amp use, but very non linear when driven by G1.
It does work well when driven on G2, but then it needs more drive and drive must be at about +130v !!!

Ed