How rugged are vintage 2A3 tubes?

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Posted by LowRedMoon (A) on October 23, 2020 at 09:47:38

I'm building a pair of push pull 2A3 amplifiers using RCA bi-plate 2A3s. The design I'm startimg with is Pete Millett's PP 6B4G, except with 2A3 tubes, with individual 2.5V 3A AC heater supplies (Hammond 166M5 - no center tap) and a 750 ohm 10W resistor between each cathode and ground.
As published, this will run each 2A3 at 15W dissipation (100% of RCA's dissipation rating). This seems to be pretty common for cathode biased push pull 2A3 designs.
Is the RCA 2A3 able to be pushed that hard without wearing out quickly? They are expensive, and I'd like to run them at a point that won't chew them up too quickly.
I know how to adjust the bias, but I'm still new to drawing composite curves.

Thanks for your input!

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Topic - How rugged are vintage 2A3 tubes? - LowRedMoon 09:47:38 10/23/20 (15)

Great thread guys! - Jim D. 06:16:42 10/30/20 (1)

RE: Great thread guys! - rmyauck 19:03:43 02/03/21 (0)

RE: How rugged are vintage 2A3 tubes? - ivan_terrible 07:58:35 10/26/20 (0)

RE: How rugged are vintage 2A3 tubes? - dave slagle 06:31:31 10/24/20 (7)

Have you ever pushed a 2A3 to 20W dissipation? (nt) - LowRedMoon 18:30:44 10/25/20 (2)

RE: Have you ever pushed a 2A3 to 20W dissipation? (nt) - dave slagle 05:07:42 10/26/20 (1)

Great! Glad to hear that. (nt) - LowRedMoon 11:11:19 10/26/20 (0)

RE: How rugged are vintage 2A3 tubes? - LowRedMoon 07:56:12 10/25/20 (0)

RE: How rugged are vintage 2A3 tubes? - kobasa@xs4all.nl 12:03:49 10/24/20 (2)

RE: How rugged are vintage 2A3 tubes? - LowRedMoon 08:06:25 10/25/20 (1)

RE: How rugged are vintage 2A3 tubes? - kobasa@xs4all.nl 12:08:01 10/25/20 (0)

RE: How rugged are vintage 2A3 tubes? - Paul Joppa 16:10:15 10/23/20 (1)

RE: How rugged are vintage 2A3 tubes? - LowRedMoon 17:46:30 10/23/20 (0)

RE: How rugged are vintage 2A3 tubes? - kobasa@xs4all.nl 12:10:38 10/23/20 (1)

RE: How rugged are vintage 2A3 tubes? - LowRedMoon 17:46:52 10/23/20 (0)

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