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21. [AMPS] series filaments (score: 1): Author: w8jitom@postoffice.worldnet.att.net (w8jitom@postoffice.worldnet.att.net); Date: Fri, 14 Nov 1997 07:20:05 +0000; Hi Peter, The problems associated with series filaments would escape anyone who considers the accumulated damage to be a current-only time independent problem. With a one track "it's the magnetic fie; /archives//html/Amps/1997-11/msg00197.html (9,483 bytes)
22. [AMPS] VHF amp bias (score: 1): Author: w8jitom@postoffice.worldnet.att.net (w8jitom@postoffice.worldnet.att.net); Date: Fri, 14 Nov 1997 07:20:06 +0000; Carl sez: They will continue to use it until more people start to care about signal purity on VHF, and let them know they care. Actually the diode works very well if the stage has very little RF dri; /archives//html/Amps/1997-11/msg00198.html (9,393 bytes)
23. [AMPS] MLA 2500B mod (score: 1): Author: w8jitom@postoffice.worldnet.att.net (w8jitom@postoffice.worldnet.att.net); Date: Sun, 16 Nov 1997 07:13:15 +0000; Hi Johnny, Be careful with that "mod". It has very poor screen regulation, greatly overtaxes the 120 volt (12 VA ICAS) winding of the Dentron power transformer, and drives too easy for most exciters; /archives//html/Amps/1997-11/msg00210.html (7,760 bytes)
24. [AMPS] series filaments (score: 1): Author: w8jitom@postoffice.worldnet.att.net (w8jitom@postoffice.worldnet.att.net); Date: Mon, 17 Nov 1997 08:58:36 +0000; It's mostly a function of surface area with indirectly heated tubes, so they can have very high peak emissions. There are no hard and fast rules for indirectly heated tubes. They are permanently dam; /archives//html/Amps/1997-11/msg00225.html (9,094 bytes)
25. [AMPS] Alpha 87A Owners! - I want to hear from you!! (score: 1): Author: w8jitom@postoffice.worldnet.att.net (w8jitom@postoffice.worldnet.att.net); Date: Tue, 18 Nov 1997 07:52:33 +0000; More nonsense designed to sell magical "kits" . 8877's, both in commercial and amateur service, had a very high failure rate through the 80's and early 90's. Over 90% of some batches of tubes would; /archives//html/Amps/1997-11/msg00238.html (9,888 bytes)
26. [AMPS] AMPLIFIER QUESTIONS? (score: 1): Author: w8jitom@postoffice.worldnet.att.net (w8jitom@postoffice.worldnet.att.net); Date: Tue, 18 Nov 1997 07:52:33 +0000; Hi Gerald. The Bird, Drake, and even the lowly MFJ meter are ALL directional couplers that respond to current AND voltage. If the current is half, the voltage is double....and vice versa for a const; /archives//html/Amps/1997-11/msg00239.html (9,153 bytes)
27. [AMPS] RE: 8877 failures; thoriated tungsten vs. indirectly (score: 1): Author: w8jitom@postoffice.worldnet.att.net (w8jitom@postoffice.worldnet.att.net); Date: Tue, 18 Nov 1997 09:11:45 +0000; Hi Rich, I don't know what Dick did, but I can tell you I opened and inspected tubes...as did Eimac. There were two modes of failure. One was the heat dam problems Dick pointed out, and another was; /archives//html/Amps/1997-11/msg00240.html (8,787 bytes)
28. [AMPS] USE OF AUTO TRANSFORMER (score: 1): Author: w8jitom@postoffice.worldnet.att.net (w8jitom@postoffice.worldnet.att.net); Date: Tue, 18 Nov 1997 09:11:45 +0000; Hi Bob, You can run into several problems. First, all steel cores saturate at some flux level. When that happens, any additional primary voltage no longer adds core flux at the same rate. The result; /archives//html/Amps/1997-11/msg00241.html (9,510 bytes)
29. [AMPS] series filaments (score: 1): Author: w8jitom@postoffice.worldnet.att.net (w8jitom@postoffice.worldnet.att.net); Date: Tue, 18 Nov 1997 09:11:46 +0000; To: <amps@contesting.com> Rich. Read more carefully. I said it was a bias problem that affected emission. Bias voltage does affect emission, at least in my gridded tubes. 73, Tom W8JI -- FAQ on WWW:; /archives//html/Amps/1997-11/msg00242.html (8,651 bytes)
30. [AMPS] USE OF AUTO TRANSFORMER (score: 1): Author: w8jitom@postoffice.worldnet.att.net (w8jitom@postoffice.worldnet.att.net); Date: Wed, 19 Nov 1997 07:51:51 +0000; 73, Tom W8JI -- FAQ on WWW: http://www.contesting.com/ampfaq.html Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com Search: ht; /archives//html/Amps/1997-11/msg00266.html (9,490 bytes)
31. [AMPS] Re: series filaments (score: 1): Author: w8jitom@postoffice.worldnet.att.net (w8jitom@postoffice.worldnet.att.net); Date: Thu, 20 Nov 1997 07:17:51 +0000; OK, let me re-word that. It affects the anode and grid current sourced by the filament, by changing the BIAS voltage from each area of the filament. IMO, it's a poor idea to have one end of a direct; /archives//html/Amps/1997-11/msg00281.html (7,638 bytes)
32. [AMPS] Re question (score: 1): Author: w8jitom@postoffice.worldnet.att.net (w8jitom@postoffice.worldnet.att.net); Date: Thu, 20 Nov 1997 07:17:51 +0000; Exactly the same. I can't think of how to make one that isn't the same. The all respond to the SUM of line voltage and current. Within the published accuracy of the meter (+ or - 5% of FS anywhere o; /archives//html/Amps/1997-11/msg00282.html (7,643 bytes)
33. [AMPS] tube compatability (score: 1): Author: w8jitom@postoffice.worldnet.att.net (w8jitom@postoffice.worldnet.att.net); Date: Thu, 20 Nov 1997 07:17:51 +0000; Same tube in this case Steve, but better testing. Be sure to add a grid over-current protection circuit to your amp. If it does not have one, or you will eat up the new tubes. A fuse is NOT enough,; /archives//html/Amps/1997-11/msg00283.html (8,588 bytes)
34. [AMPS] Screen Supplys (score: 1): Author: w8jitom@postoffice.worldnet.att.net (w8jitom@postoffice.worldnet.att.net); Date: Thu, 20 Nov 1997 08:15:59 +0000; Hi Ian, I certainly agree with you Ian. Zeners make poor regulators for screen supplies unless you use some type of gain loop to reduce the effective ESR of the supply, and hold the current in the z; /archives//html/Amps/1997-11/msg00285.html (8,610 bytes)
35. [AMPS] Solid State Relay for Anode Primary ? (score: 1): Author: w8jitom@postoffice.worldnet.att.net (w8jitom@postoffice.worldnet.att.net); Date: Thu, 20 Nov 1997 08:15:59 +0000; Hi Dave, That's a total misconception Dave, and you are not alone. One amplifier manufacturer I know of also sells an amp with a zero crossing turn on "thinking" and claiming it limits inrush. What; /archives//html/Amps/1997-11/msg00286.html (8,669 bytes)
36. [AMPS] tube compatability (score: 1): Author: w8jitom@postoffice.worldnet.att.net (w8jitom@postoffice.worldnet.att.net); Date: Fri, 21 Nov 1997 09:50:21 +0000; We've been over this a hundred times. You wrongly insist you can simply multiply the RMS drive voltage against the indicated meter current. That's nonsense. We have no idea what the grid dissipation; /archives//html/Amps/1997-11/msg00307.html (9,170 bytes)
37. [AMPS] tube compatability (score: 1): Author: w8jitom@postoffice.worldnet.att.net (w8jitom@postoffice.worldnet.att.net); Date: Fri, 21 Nov 1997 09:50:21 +0000; Hi Bob, You might contact Ten Tec and see what they did to the later units. Otherwise, Ameritron can sell a timer-overload board that is easily modified for any rig. It responds within a few millisec; /archives//html/Amps/1997-11/msg00308.html (9,253 bytes)
38. [AMPS] Loading problem (score: 1): Author: w8jitom@postoffice.worldnet.att.net (w8jitom@postoffice.worldnet.att.net); Date: Fri, 21 Nov 1997 09:50:21 +0000; To: <amps@contesting.com> Ken, The usual problem is not enough inductance in the anode RF choke, or drifting and small padding capacitors in the tank. A better description of the tank and choke woul; /archives//html/Amps/1997-11/msg00309.html (7,611 bytes)
39. [AMPS] SB 220 vice SB221 (score: 1): Author: w8jitom@postoffice.worldnet.att.net (w8jitom@postoffice.worldnet.att.net); Date: Sun, 23 Nov 1997 08:10:16 +0000; Hi Bob and all, That's utter nonsense. The spitting and sputtering is not due to parasitics at all. The plate variable/ tank arcing problem most often is incorrect tuning, and secondarily incorrect r; /archives//html/Amps/1997-11/msg00323.html (10,230 bytes)
40. [AMPS] SB 220 vice SB221 (score: 1): Author: w8jitom@postoffice.worldnet.att.net (w8jitom@postoffice.worldnet.att.net); Date: Mon, 24 Nov 1997 07:39:42 +0000; If you read what I wrote carefully, you'll see I specified the tank IS resonant, the load is simply removed. How this happens is simple. A tube appears like a diode in series with a time varying res; /archives//html/Amps/1997-11/msg00336.html (12,364 bytes)

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