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1. [Amps] Life and gain of 3-500Z (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Tue, 18 Jul 2006 06:14:21 -0400; The filament life issue is primarily an issue with good manufacturing quality and steady operation at conservative values. Say you run a tube 24/7/52. In a week you have 168 hours. In a year 8736 ho; /archives//html/Amps/2006-07/msg00558.html (9,465 bytes)
2. Re: [Amps] Life and gain of 3-500Z (score: 1): Author: R L Measures <r@somis.org>; Date: Tue, 18 Jul 2006 04:07:28 -0700; As a thoriated tungsten filament ages, carbon atoms slowly depart from the ditungsten carbide (W^2C) emissive-layer, leaving tungsten behind. Since tungsten is more conductive than ditungsten carbide; /archives//html/Amps/2006-07/msg00568.html (11,105 bytes)
3. Re: [Amps] Life and gain of 3-500Z (score: 1): Author: "k7rdx" <k7rdx@charter.net>; Date: Tue, 18 Jul 2006 07:09:15 -0700; The tubes (3-500z`s) were from RF Parts. I replaced (Henry 3K repair job)some low hr Eimacs that one had developed a grid to filament short. Gain was compared to a nos pair of Eimac`s.Higher zsac for; /archives//html/Amps/2006-07/msg00569.html (11,297 bytes)
4. Re: [Amps] Life and gain of 3-500Z (score: 1): Author: "Mike Schatzberg" <cherokeehillfarm@earthlink.net>; Date: Tue, 18 Jul 2006 10:33:46 -0400; So Jim, with the new Chinese tubes, RF Parts (probably made by Pride), with a 3,200 VDC supply, a reasonably stiff AC mains (240 volts at 30 amps), and a drive limit of 100 Watts, idling current set; /archives//html/Amps/2006-07/msg00571.html (12,868 bytes)
5. Re: [Amps] Life and gain of 3-500Z (score: 1): Author: Joe Isabella <n3ji@yahoo.com>; Date: Tue, 18 Jul 2006 07:37:15 -0700 (PDT); I noticed the same thing on my amps. The RF Parts 3-500ZGs had more output in both my TL-922 and the Henry. The first set of Eimacs (that were in the TL-922) had bad plate welds that eventually short; /archives//html/Amps/2006-07/msg00572.html (12,618 bytes)
6. Re: [Amps] Life and gain of 3-500Z (score: 1): Author: "Mike Schatzberg" <cherokeehillfarm@earthlink.net>; Date: Tue, 18 Jul 2006 10:41:44 -0400; Oh, one last parameter, please allow for the grids to be strapped to ground also. Sorry for the omission. Gain _______________________________________________ Amps mailing list Amps@contesting.com ht; /archives//html/Amps/2006-07/msg00573.html (12,447 bytes)
7. Re: [Amps] Life and gain of 3-500Z (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Tue, 18 Jul 2006 12:28:32 -0400; The trend is generally this: Higher quiescent current for fixed bias and HV generally indicates lower mu, not higher. It takes more negative bias to reduce anode current as mu is increased. Lower mu; /archives//html/Amps/2006-07/msg00581.html (9,710 bytes)
8. Re: [Amps] Life and gain of 3-500Z (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Tue, 18 Jul 2006 12:29:58 -0400; What is the fusing current rating of the resistor? Why would you fuse a grid? 73 Tom _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com; /archives//html/Amps/2006-07/msg00582.html (9,033 bytes)
9. Re: [Amps] Life and gain of 3-500Z (score: 1): Author: "k7rdx" <k7rdx@charter.net>; Date: Tue, 18 Jul 2006 14:00:37 -0700; If your theory is correct concerning tube gain (Mu) how do you explain this: A gs-35b requires around 40 volts bias for zsac of 150ma with 4kv Ep...A 8877 at the same Ep requires much less for simila; /archives//html/Amps/2006-07/msg00595.html (10,755 bytes)
10. Re: [Amps] Life and gain of 3-500Z (score: 1): Author: "Phil Clements" <philc@texascellnet.com>; Date: Tue, 18 Jul 2006 16:53:03 -0500; Assuming it is correct that the Chinese tubes are higher mu, and higher gain than an Eimac, the zsac would be higher, and the input vswr would change, with the same HV and bias voltages applied? (((; /archives//html/Amps/2006-07/msg00597.html (8,857 bytes)
11. Re: [Amps] Life and gain of 3-500Z (score: 1): Author: "Peter Voelpel" <df3kv@t-online.de>; Date: Wed, 19 Jul 2006 00:12:14 +0200; When I recently repaired a TL-922 for a friend the original tubes where replaced by RFP 3-500ZG. There was no adjustment necessary to the input circuits, if I remember right the idling current in SSB; /archives//html/Amps/2006-07/msg00599.html (9,818 bytes)
12. Re: [Amps] Life and gain of 3-500Z (score: 1): Author: R L Measures <r@somis.org>; Date: Tue, 18 Jul 2006 09:37:17 -0700; Amperex 3-500Zs have an avg. Mu of c. 190 compared to Eimac's 130. I measure about the same PEP output from either brand, but Amperexes require c. 10% less drive to get there. ... R L MEASURES, AG6K.; /archives//html/Amps/2006-07/msg00601.html (9,547 bytes)
13. Re: [Amps] Life and gain of 3-500Z (score: 1): Author: R L Measures <r@somis.org>; Date: Tue, 18 Jul 2006 09:48:33 -0700; Before strapping a grid directly to ground, please measure the grid's resonant frequency with a dipmeter. After strapping a grid to ground, please re-measure the resonant frequency and publish the re; /archives//html/Amps/2006-07/msg00602.html (13,741 bytes)
14. Re: [Amps] Life and gain of 3-500Z (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Tue, 18 Jul 2006 19:07:27 -0400; Hi Jim, Yes. For a clearer example, look at tubes with very similar internal geometry and ratings but different mu. Try the 3CX3000A1 and 3CX3000A7 You will see the higher the mu, the less grid bias; /archives//html/Amps/2006-07/msg00603.html (11,902 bytes)
15. Re: [Amps] Life and gain of 3-500Z (score: 1): Author: "Mike Schatzberg" <cherokeehillfarm@earthlink.net>; Date: Tue, 18 Jul 2006 19:08:49 -0400; According to the Richardson Electronics Data Sheet for the Amperex 3-500Z, with the heavy graphite anode with the zirconium coating, the amplification factor for the tube is 130 average. Richardson a; /archives//html/Amps/2006-07/msg00606.html (11,366 bytes)
16. Re: [Amps] Life and gain of 3-500Z (score: 1): Author: Steve Katz <stevek@jmr.com>; Date: Tue, 18 Jul 2006 16:07:09 -0700; Good old Richardson...a pox on them! (General discussion, unrelated to 3-500Zs...) -WB2WIK/6 According to the Richardson Electronics Data Sheet for the Amperex 3-500Z, with the heavy graphite anode w; /archives//html/Amps/2006-07/msg00607.html (9,371 bytes)
17. Re: [Amps] Life and gain of 3-500Z (score: 1): Author: R L Measures <r@somis.org>; Date: Tue, 18 Jul 2006 18:55:46 -0700; correct. the opposite is true. Example -- With higher Mu Amperex tubes in a SB-220, the 5V bias zener needs to be shorted (0V) to increase the ZSAC. correct In g-g configuration, lower Mu means highe; /archives//html/Amps/2006-07/msg00624.html (10,765 bytes)
18. Re: [Amps] Life and gain of 3-500Z (score: 1): Author: R L Measures <r@somis.org>; Date: Tue, 18 Jul 2006 19:09:40 -0700; What was wrong with them, Peter? R L MEASURES, AG6K. 805-386-3734 r@somis.org _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman; /archives//html/Amps/2006-07/msg00625.html (10,992 bytes)
19. Re: [Amps] Life and gain of 3-500Z (score: 1): Author: R L Measures <r@somis.org>; Date: Tue, 18 Jul 2006 18:57:55 -0700; Because 0.25w carbon-film resistors cost less than 3-500s. R L MEASURES, AG6K. 805-386-3734 r@somis.org _______________________________________________ Amps mailing list Amps@contesting.com http://li; /archives//html/Amps/2006-07/msg00631.html (9,637 bytes)
20. Re: [Amps] Life and gain of 3-500Z (score: 1): Author: "Mike Schatzberg" <cherokeehillfarm@earthlink.net>; Date: Wed, 19 Jul 2006 11:20:30 -0400; "the opposite is true. Example -- With higher Mu Amperex tubes in a SB-220, the 5V bias zener needs to be shorted (0V) to increase the ZSAC." The published data sheets as per the Richardson , state t; /archives//html/Amps/2006-07/msg00636.html (10,349 bytes)

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