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21. [AMPS] SB-1000 mods? (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Sat, 8 Sep 2001 15:35:07 -0400; My homemade PA has a pair of 50 ohm ~200 watt very long carbon resistors in parallel. It dumps a primary disconnect during a fault of over 5 amperes. Normally all I hear is a little faint tic as it; /archives//html/Amps/2001-09/msg00140.html (9,209 bytes)
22. [AMPS] SB-1000 mods? (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Sat, 8 Sep 2001 15:35:07 -0400; The resistor must be surge rated for the voltage across the resistor and the peak energy. RCD makes xxx-P series pulse rated resistors, or you can use a "glow-bar" type. The RCD pulse rated resistor; /archives//html/Amps/2001-09/msg00141.html (9,666 bytes)
23. [AMPS] SB-1000 mods? (score: 1): Author: 2@vc.net (2); Date: Sat, 8 Sep 2001 16:30:11 -0700; Tom: Do u have a phone number or a URL? - R. L. Measures, 805.386.3734,AG6K, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administra; /archives//html/Amps/2001-09/msg00147.html (9,418 bytes)
24. [AMPS] SB-1000 mods? (score: 1): Author: philk5pc@tyler.net (Phil Clements); Date: Sat, 8 Sep 2001 21:12:40 -0500; The point is that they are both too small if they fail. At C. 3800-4000v, a 10 ohm 10 watt resistor will fail. The glass coated ones usually break cleanly, as if they were sawed in two. I have learne; /archives//html/Amps/2001-09/msg00149.html (9,039 bytes)
25. [AMPS] SB-1000 mods? (score: 1): Author: 2@vc.net (2); Date: Sat, 8 Sep 2001 21:26:36 -0700; // Failure is also dependent on the number of watt-seconds/Joules of stored energy in the filter C. How about putting two 10Wers in series for potentials above 3kV? cheers, Phil - R. L. Measures, 80; /archives//html/Amps/2001-09/msg00151.html (9,607 bytes)
26. [AMPS] SB-1000 mods? (score: 1): Author: Mike" <W4EF@dellroy.com (Mike); Date: Sun, 9 Sep 2001 15:14:08 -0700; Looks like the RCD resistors will do the trick (the 20W parts should fit nicely in the space available inside the L-7 PS). Thanks to Tom, Rich, Todd, Ian, Phil et al for the quick education on glitch; /archives//html/Amps/2001-09/msg00159.html (10,510 bytes)
27. [AMPS] SB-1000 mods? (score: 1): Author: 2@vc.net (2); Date: Sun, 9 Sep 2001 16:11:27 -0700; Their 5Watter (140 watt-seconds/joules) will do an L-7 with ease since stored energy is c. 80-joules. If you get a price, please post it. cheers, Mike. - R. L. Measures, 805.386.3734, AG6K, www.vcne; /archives//html/Amps/2001-09/msg00160.html (11,063 bytes)
28. [AMPS] SB-1000 mods? (score: 1): Author: Mike" <W4EF@dellroy.com (Mike); Date: Sun, 9 Sep 2001 19:27:07 -0700; Hi Rich, Would there be any concern about the lower maximum resistance dictated by the use of the 5 watt steady-state rating versus using a 20 or 50 watt resistor? At 750mA worst case steady-state an; /archives//html/Amps/2001-09/msg00163.html (12,542 bytes)
29. [AMPS] SB-1000 mods? (score: 1): Author: 2@vc.net (2); Date: Sun, 9 Sep 2001 20:13:11 -0700; // The power supply is not able to do 750mA continuous. Average duty-cycle on SSB is c. 15% - CW is c. 30%. // The lowest value made is 10-ohms. // A faster dump means more peak current. ESR adds pe; /archives//html/Amps/2001-09/msg00164.html (13,560 bytes)
30. [AMPS] SB-1000 mods? (score: 1): Author: Mike" <W4EF@dellroy.com (Mike); Date: Sun, 9 Sep 2001 21:03:50 -0700; Hi Rich, Yes, of course, a faster dump means more peak current - that is my concern. The 10 ohm resistor and the components/wiring in series with it will experience a peak current ~3.6 times greater; /archives//html/Amps/2001-09/msg00165.html (15,081 bytes)
31. [AMPS] SB-1000 mods? (score: 1): Author: philk5pc@tyler.net (Phil Clements); Date: Mon, 10 Sep 2001 00:02:18 -0500; Eimac's bulletin says that they want the peak energy limited to 50 joules. They say that a 50 ohm resistor will limit current to 40 amps. If the value of the resistor is larger than necessary, it wil; /archives//html/Amps/2001-09/msg00167.html (9,580 bytes)
32. [AMPS] SB-1000 mods? (score: 1): Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK); Date: Mon, 10 Sep 2001 10:08:56 +0100; The real limitation for this application is power dissipation in normal operation. For say a 30 ohm resistance, 5W size clearly won't handle even 0.5A. Dissipation is downrated drastically with ambie; /archives//html/Amps/2001-09/msg00173.html (9,978 bytes)
33. [AMPS] SB-1000 mods? (score: 1): Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK); Date: Mon, 10 Sep 2001 10:28:46 +0100; Not my thumb, but Eimac's. Based on the 40A limit that Phil summarizes below, it would actually be 25 ohms per kV. However, many people tend to use less than this (in consideration of the voltage dr; /archives//html/Amps/2001-09/msg00174.html (11,469 bytes)
34. [AMPS] SB-1000 mods? (score: 1): Author: philk5pc@tyler.net (Phil Clements); Date: Mon, 10 Sep 2001 10:00:23 -0500; Jolly good show, Ian! It will save us all a lot of typing every time the subject comes up! Many thanks! Phil, K5PC -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com; /archives//html/Amps/2001-09/msg00178.html (9,189 bytes)
35. [AMPS] SB-1000 mods? (score: 1): Author: 2@vc.net (2); Date: Mon, 10 Sep 2001 09:28:20 -0700; // Ohm's Law: P=I^2 x R = 0.5A x 0.5A x 10-ohms = 2.5W. On SSB duty-cycle is around 30%, so avg. dissipation should be c. 2w. 5-second dissipation for a PCN5 is rated at 50 watts. // So, when operat; /archives//html/Amps/2001-09/msg00180.html (10,470 bytes)
36. [AMPS] SB-1000 mods? (score: 1): Author: 2@vc.net (2); Date: Mon, 10 Sep 2001 09:28:21 -0700; // Typical ESR in a modern 200uF, 450v electrolytic filter cap is c. 0.5-ohms. Eight such caps would be c, 4-ohms. At 3200v, peak discharge current would limit at c. 700A. In my opinion, this is not; /archives//html/Amps/2001-09/msg00181.html (13,242 bytes)
37. [AMPS] SB-1000 mods? (score: 1): Author: 2@vc.net (2); Date: Mon, 10 Sep 2001 09:28:23 -0700; // 20-ohms/kV would be c. 60-ohms for a 3kV anode supply amplifier. However 10-0hms apparently works ok in a SB-220, of course, c. 1-ohm is added by the 2 RFCs and a bit more from the ESR of the 8 f; /archives//html/Amps/2001-09/msg00182.html (9,258 bytes)
38. [AMPS] SB-1000 mods? (score: 1): Author: W8JI@contesting.com (Tom Rauch); Date: Mon, 10 Sep 2001 13:16:39 -0400; RCD? I'd suggest people check manufacturers. I'm sure many have stock components that will do. For example, Ameritron has a variety of globar resistors and also a 400 joule 13 watt dissipation 1500; /archives//html/Amps/2001-09/msg00185.html (9,775 bytes)
39. [AMPS] SB-1000 mods? (score: 1): Author: 2@vc.net (2); Date: Mon, 10 Sep 2001 11:33:27 -0700; // At one time, no Ameritron/MFJ amplifier used a glitch resistor. Which models currently do, Me. Rauch? tnx. // Amen to that. A fast-acting 250v fuse in the power transformer's primary in the scrre; /archives//html/Amps/2001-09/msg00189.html (10,122 bytes)
40. [AMPS] SB-1000 mods? (score: 1): Author: Ian White, G3SEK" <g3sek@ifwtech.com (Ian White, G3SEK); Date: Mon, 10 Sep 2001 18:48:45 +0100; Count on it :-) 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 Submissions: a; /archives//html/Amps/2001-09/msg00191.html (9,113 bytes)

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