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1. [Amps] sb-220 questions (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Fri, 20 Feb 2004 16:04:38 -0800; All, I just picked up an sb-220 and it is not behaving 'properly'. It draws about 100 ma of plate current with no input, just the relay closed. Is this normal?? It behaves predictably up to about 20; /archives//html/Amps/2004-02/msg00194.html (7,015 bytes)
2. Re: [Amps] sb-220 questions (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Sat, 21 Feb 2004 16:23:35 -0800; All, follow-up; The 100 ma idle plate current is on low power. It is 140 ma on high power; so the "idle" state seems ok. However the amp defiantly will not put out full power. Grid current 'hockey st; /archives//html/Amps/2004-02/msg00201.html (9,291 bytes)
3. [Amps] sb-220 80 meter output cap ?? (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Sun, 22 Feb 2004 18:34:57 -0800; All, Wow!! The journey to understand and incorporate this amp has been problematic. The first symptoms seemed to point toward a total amp problem such as very weak tubes. However it was a trail a win; /archives//html/Amps/2004-02/msg00209.html (7,168 bytes)
4. [Amps] sb-220 non uniform grid current ?? (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Tue, 24 Feb 2004 15:06:40 -0800; All, I have an sb-220 with non-uniform grid current. With low to medium drive grid current is linear (or apparently close to it) with plate current (minus about 100 ma base) and output power. However; /archives//html/Amps/2004-02/msg00232.html (7,228 bytes)
5. Re: [Amps] sb-220 non uniform grid current ?? (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Wed, 25 Feb 2004 08:25:15 -0800; Thanks, The following data was collected from an antenna with an SWR of about 1.5. Plate ma Grid ma 100 0 120 10 140 20 160 30 180 40 200 50 300 100 600 150 These were obtained by carefully increasin; /archives//html/Amps/2004-02/msg00243.html (9,323 bytes)
6. Re: [Amps] sb-220 non uniform grid current ?? (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Wed, 25 Feb 2004 10:46:21 -0800; Thank you, The exciter is a Heathkit 5400. In the last reading below it is driving the amp with about 30 watts. If I increase the input drive power from that point the grid current rises very rapidly; /archives//html/Amps/2004-02/msg00246.html (10,677 bytes)
7. Re: [Amps] Sb-220 grid Chokes (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Wed, 25 Feb 2004 10:57:22 -0800; All, What is the recommended grid-gnd circuit?? The original sb-220 had an LC network; it seems to be a common recommendation to replace the coil with a 33 OHM resister. Are the caps changed as well?; /archives//html/Amps/2004-02/msg00247.html (8,380 bytes)
8. [Amps] high sb-220 grid current - follow up ?? (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Sat, 28 Feb 2004 12:14:53 -0800; All, I posted here about an SB-220 exhibiting non-linear, hockey stick, grid current. This pattern starts at between 20 and 30 watts drive. This post is after gaining additional information. My habit; /archives//html/Amps/2004-02/msg00299.html (7,998 bytes)
9. [Amps] sb-220 tuning question - closing in (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Tue, 02 Mar 2004 16:12:02 -0800; All, I am closing in on 'tuning' an sb-220. To make a long story short I was tuning at low power and running it at a higher power. Now I am tuning up incrementally in 3 steps from 10 watts to 100 wat; /archives//html/Amps/2004-03/msg00023.html (7,609 bytes)
10. [Amps] a really dumb question ?? (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Thu, 11 Mar 2004 19:04:43 -0800; All, I have an amplifier with two MFR150's in a push pull configuration. Each transistor is rated at 150 watts. Is the max output 150 or 300 watts?? Part of me argues because each transistor is only; /archives//html/Amps/2004-03/msg00120.html (6,895 bytes)
11. [Amps] transistor specs ?? (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Thu, 11 Mar 2004 21:16:37 -0800; All, I have picked an HF amp with two stages. The driver stages uses ST or STi transistors labeled 148; the output stages uses ST or STi transistors labeled TH 430 C. I cannot find specs for these. D; /archives//html/Amps/2004-03/msg00121.html (6,830 bytes)
12. [Amps] off topic - loaded verticles ?? (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Wed, 31 Mar 2004 21:30:47 -0800; All, I am trying tune a loaded vertical. Do any of you know about a reflector that would deal with loaded vertical topics such as input impedance and resonance calculations?? Thanks, Dan ____________; /archives//html/Amps/2004-04/msg00000.html (6,502 bytes)
13. [Amps] help with mosfet power amp (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Sun, 25 Apr 2004 15:41:12 -0700; All, I need help in learning how to handle and bring up a power mosfet amp. I have purchased a single stage power amp with 2 MRF154's. The amp has three inputs, power, RF in, and RF out. The power in; /archives//html/Amps/2004-04/msg00198.html (7,560 bytes)
14. [Amps] proud owner of a 1000 watt MOSFET amp ?? (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Thu, 29 Apr 2004 20:21:44 -0700; All, I am the proud owner of a dual MRF154 MOSFET amp. It is a surplus amp without directions. There are 5 connections; 3 are well marked, they are RF IN, RF OUT, and VCC +50. The 2 remaining ones ar; /archives//html/Amps/2004-04/msg00246.html (7,101 bytes)
15. [Amps] yeah - it works !! (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Sat, 01 May 2004 18:42:28 -0700; All, I recently posted "proud owner of a ... MRF154 amp" and got back a lot of helpful replies. Well I brought up the gate voltage first. The current draw was very low and there was no bias across th; /archives//html/Amps/2004-05/msg00018.html (7,662 bytes)
16. [Amps] cooling a high power rf mosfet amp?? (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Sun, 02 May 2004 19:49:23 -0700; All, The MRF154 amp is working well. The gain is 19db in the 80 and 40 meter bands. The move from 30 Volts Vcc to 50 Volts was uneventful. That move went without incident and it resulted in improved; /archives//html/Amps/2004-05/msg00026.html (7,194 bytes)
17. [Amps] ganging 2 switching power supplies in parallel (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Wed, 05 May 2004 20:23:16 -0700; Hello, I need to gang two switching power in parallel to double current capacity. What is a good voltage drop to target for the balancing resistors?? Thanks, Dan _____________________________________; /archives//html/Amps/2004-05/msg00057.html (6,926 bytes)
18. [Amps] MRF154 amp update (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Sun, 09 May 2004 09:47:41 -0700; All, I have been bringing an MRF 154 based amp on line for HF. The process of 'configuring' the power supplies is going smoothly. The design is based on ganging 5 x 500 watt switching supplies. The v; /archives//html/Amps/2004-05/msg00101.html (8,128 bytes)
19. [Amps] exciter compression ?? (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Sat, 15 May 2004 16:24:42 -0700; Hello, I am starting this thread here because it relates to linears although the actual question is about exciters. I have a 1 KW solid state linear with a gain of about 20db. This implies 10 watts d; /archives//html/Amps/2004-05/msg00133.html (6,860 bytes)
20. [Amps] a 'circuits' question (score: 1): Author: Dan Sawyer <dansawyer@earthlink.net>; Date: Wed, 08 Sep 2004 06:44:21 -0700; This is a circuits question from a 575 curve tracer being used to match MOSFETs for an HF amp so it is a least close to topic. The problem is the difference in granularity between the 'steps' circuit; /archives//html/Amps/2004-09/msg00171.html (7,605 bytes)

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