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1. [AMPS] DC Filaments??? (score: 1): Author: jeff@wa1hco.mv.com (jeff millar); Date: Wed, 1 Nov 2000 02:09:58 -0500; Then why to tubes have a finite service life? Maybe because the filament gets poisoned by gases...then DC or AC won't matter. Maybe because sustained emission degrades emission...then DC will make a; /archives//html/Amps/2000-11/msg00002.html (9,529 bytes)
2. [AMPS] DC Filaments??? (score: 1): Author: Wlfuqu00@pop.uky.edu (William Fuqua); Date: Wed, 01 Nov 2000 09:07:49 -0500; The amount of current drawn form the cathode has nothing to do with the emission life. In fact the hot cathode produces a cloud of electrons around it and creates a virtual cathode that is about one; /archives//html/Amps/2000-11/msg00004.html (8,421 bytes)
3. [AMPS] DC Filaments??? (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Wed, 1 Nov 2000 12:58:49 -0500; That's my understanding also, with the exception of MOX cathode tubes that can be permanently damaged by excessive high voltage or use of the cathode at emission limits (cathode too cold for the amo; /archives//html/Amps/2000-11/msg00006.html (9,338 bytes)
4. [AMPS] DC Filaments??? (score: 1): Author: n1rj@pivot.net (Roger D. Johnson); Date: Wed, 01 Nov 2000 16:45:36 -0500; I've heard pilot lamps last longer when run on AC but I'm not sure why. BTW the reason the ART-13, T-195, etc filaments were run on DC is that they are aircraft/mobile rigs where the primary power is; /archives//html/Amps/2000-11/msg00010.html (7,936 bytes)
5. [AMPS] DC Filaments??? (score: 1): Author: jeff@wa1hco.mv.com (jeff millar); Date: Wed, 1 Nov 2000 20:48:21 -0500; Even with AC on the filament, the voltage between grid and filament varies along the length of the filament at any instant in time. The filament voltage varies very slowly compared to both the RF car; /archives//html/Amps/2000-11/msg00012.html (8,961 bytes)
6. [AMPS] DC Filaments??? (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Wed, 1 Nov 2000 21:03:17 -0500; Hi Jeff, The problem is the hum it adds, as it changes bias. I'd worry about the bias being uneven from end to end of the filament. That can't be good, if the filament voltage is a large part of the; /archives//html/Amps/2000-11/msg00013.html (9,593 bytes)
7. [AMPS] DC Filaments??? (score: 1): Author: jeff@wa1hco.mv.com (jeff millar); Date: Wed, 1 Nov 2000 21:33:12 -0500; is I though you liked AC on the filaments and saw problems with DC? RF amps with AC filaments don't seem to have hum problems from AC filaments. What did I miss, here? I tried to make the point that; /archives//html/Amps/2000-11/msg00015.html (10,354 bytes)
8. [AMPS] DC Filaments??? (score: 1): Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK); Date: Thu, 2 Nov 2000 08:01:25 +0000; In a push-pull stereo system, you MUST periodically swap the tubes around - left to right, push to pull - in order to even out the wear. Incorrect adjustment of the stereo balance can cause premature; /archives//html/Amps/2000-11/msg00018.html (9,133 bytes)
9. [AMPS] DC Filaments??? (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Thu, 2 Nov 2000 06:31:17 -0500; I think you missed the fact the bias was applied to one end of the filament, instead of the middle of the filament. I was responding to the Hi Fi amp with the directly heated filaments, and the tube; /archives//html/Amps/2000-11/msg00019.html (10,000 bytes)
10. [AMPS] DC Filaments??? (score: 1): Author: rakefet@rakefet.com (Vic Rosenthal); Date: Thu, 02 Nov 2000 07:31:47 -0800; With the advent of radially-finned anodes this advice is out of date. Tubes should only be swapped from back to front! 73, Vic, K2VCO Fresno CA -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submi; /archives//html/Amps/2000-11/msg00021.html (8,783 bytes)
11. [AMPS] DC Filaments??? (score: 1): Author: k7fm@teleport.com (Colin Lamb); Date: Thu, 2 Nov 2000 08:18:09 -0800; Statement: "With the advent of radially-finned anodes this advice is out of date. Tubes should only be swapped from back to front!" Question: Shouldn't the tubes be inverted every 6 months to even ou; /archives//html/Amps/2000-11/msg00022.html (8,625 bytes)
12. [AMPS] DC Filaments??? (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Thu, 2 Nov 2000 11:33:02 -0500; You also must after a few hours throw the tubes away, and get new ones to maintain clear crisp warm audio sound. This even applies to ham amplifiers according to one source. Dave Ingram (K4TWJ) has; /archives//html/Amps/2000-11/msg00024.html (10,070 bytes)
13. [AMPS] DC Filaments??? (score: 1): Author: kc4slk@csrlink.net (Mike Sawyer); Date: Thu, 2 Nov 2000 16:01:12 -0500; I know that because of the DC voltage, you are less subject to hum! Mike(y) W3SLK -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQU; /archives//html/Amps/2000-11/msg00029.html (10,099 bytes)
14. [AMPS] DC Filaments??? (score: 1): Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK); Date: Thu, 2 Nov 2000 16:36:03 +0000; To coin a phrase: [chortle]! 73 from Ian G3SEK Editor, 'The VHF/UHF DX Book' 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.com/g3sek -- FAQ on WWW: http://www.contesting.com/FAQ/amps S; /archives//html/Amps/2000-11/msg00030.html (9,209 bytes)
15. [AMPS] DC Filaments??? (score: 1): Author: Peter_Chadwick@mitel.com (Peter Chadwick); Date: Fri, 3 Nov 2000 11:30:42 -0000; Hi all, Just got back from holiday, which is why I haven't commented before. One problem you can get with DC on filaments is metal migration. The filaments used in battery tubes such as the 1L4, were; /archives//html/Amps/2000-11/msg00039.html (9,291 bytes)
16. [AMPS] DC Filaments??? (score: 1): Author: ohashi@ny.airnet.ne.jp (ohashi); Date: Sat, 04 Nov 2000 10:26:39 +0900; Peter, Thank you very much for your nice information. As I mentioned in my previous post, I swap my 211's every half year. This is intended to reverse the DC polarity for each tube's filament. I was; /archives//html/Amps/2000-11/msg00050.html (8,327 bytes)
17. [AMPS] DC Filaments??? (score: 1): Author: randyd@specent.com (Randall D. DuCharme); Date: Tue, 31 Oct 2000 18:37:23 -0600; Greetings, I was toying with the idea of running the filaments DC in an 813 amplifier I'm starting. I was just told today that if I did that I'd have to reverse the polarity on the tubes periodically; /archives//html/Amps/2000-10/msg00001.html (7,489 bytes)
18. [AMPS] DC Filaments??? (score: 1): Author: jeff@wa1hco.mv.com (jeff millar); Date: Tue, 31 Oct 2000 23:52:25 -0500; A DC filament has a varying grid to filament voltage along its length and so has uneven cathode to plate current along its length. Thus in theory, one end runs out of emission life faster than the ot; /archives//html/Amps/2000-10/msg00002.html (7,527 bytes)
19. [AMPS] DC Filaments??? (score: 1): Author: ohashi@ny.airnet.ne.jp (Kazuo Ohashi); Date: Wed, 01 Nov 2000 10:24:23 +0900; Greetings AMP folks, from Japan ! I have no experiences to use DC to 813 but I am using DC for 211(GE's VT-4C) with thoriated-tungsten filament for my home brew stereo amplifier. I applied the revers; /archives//html/Amps/2000-10/msg00003.html (8,449 bytes)
20. [AMPS] DC Filaments??? (score: 1): Author: wlfuqu00@pop.uky.edu (Bill Fuqua); Date: Tue, 31 Oct 2000 20:41:49 -0500; This is the same as saying the emission life is related to plate current. I think it is the filament temperature that determines the emission life and that is no different for DC or AC. 73 Bill wa4la; /archives//html/Amps/2000-10/msg00004.html (7,486 bytes)

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