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201. [AMPS] Switches (score: 1): Author: Peter_Chadwick@mitel.com (Peter Chadwick); Date: Thu, 12 Oct 2000 07:33:37 +0100; What do the manufacturers rate them at? Or is it a case that a switch that the manufacturers rate for the job is prohibitively expensive? 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/a; /archives//html/Amps/2000-10/msg00204.html (7,778 bytes)
202. [AMPS] MFJ-259B Question (score: 1): Author: Peter_Chadwick@mitel.com (Peter Chadwick); Date: Thu, 12 Oct 2000 08:00:42 +0100; I I bought a MFJ484 keyer for the XYL some 14 years ago. The electronics is well made: the plastic laminate is tending to unstick from the case, and the holes for the monitor speaker are randomly dri; /archives//html/Amps/2000-10/msg00205.html (9,437 bytes)
203. [AMPS] MFJ-259B Question (score: 1): Author: Peter_Chadwick@mitel.com (Peter Chadwick); Date: Thu, 12 Oct 2000 09:21:37 +0100; Ain't this the truth!!!!! But it don't stop some of them bitching about what they get for their money. Not, usually, those with any technical knowledge. But I hear some of them over here on 80m SSB,; /archives//html/Amps/2000-10/msg00208.html (9,070 bytes)
204. [AMPS] Switches (score: 1): Author: Peter_Chadwick@mitel.com (Peter Chadwick); Date: Thu, 12 Oct 2000 10:21:25 +0100; Manufacturers ratings are a very good guide. If I design in a part rated at 4kV, and at 4kV, it doesn't hack it, the manufacturer is in for a very bad time. Generally, this is why manufacturers ratin; /archives//html/Amps/2000-10/msg00212.html (8,915 bytes)
205. [AMPS] Switches (score: 1): Author: Peter_Chadwick@mitel.com (Peter Chadwick); Date: Thu, 12 Oct 2000 11:56:47 +0100; I think Tom needs a manufacturer of switches for a design to be put in production. 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative req; /archives//html/Amps/2000-10/msg00216.html (8,480 bytes)
206. [AMPS] Switches (score: 1): Author: Peter_Chadwick@mitel.com (Peter Chadwick); Date: Thu, 12 Oct 2000 13:11:31 +0100; For 9 ham bands, do you have to have 9 switch positions? 5 PA positions can cover 1.8 to 30 MHz without too much variation in operating Q; admittedly, you need something clever to switch input circui; /archives//html/Amps/2000-10/msg00219.html (8,679 bytes)
207. [AMPS] Switches (score: 1): Author: Peter_Chadwick@mitel.com (Peter Chadwick); Date: Thu, 12 Oct 2000 13:26:48 +0100; Figure the best answer is building one, given the constraints. The Rich Measures web site has enough switch horror pictures; regardless of whether or not you accept his explanation of the cause of th; /archives//html/Amps/2000-10/msg00221.html (8,660 bytes)
208. [AMPS] 811A Plate Impedance? (score: 1): Author: Peter_Chadwick@mitel.com (Peter Chadwick); Date: Mon, 16 Oct 2000 09:17:54 +0100; How come? If you double Q, do you not double the circulating current? In that case, isn't the power lost quadrupled ( I squared R) leading to 4 times as much heating? Where have I gone wrong? 73 Pete; /archives//html/Amps/2000-10/msg00358.html (7,419 bytes)
209. [AMPS] Series Tuned Tank? (score: 1): Author: Peter_Chadwick@mitel.com (Peter Chadwick); Date: Mon, 16 Oct 2000 09:35:14 +0100; Correct, if anyhting, by having a larger coil, it increases tank circuit Q. It is a technique that allows the use of a practical sized capacitor and coil, though. I've never seen it used on anything; /archives//html/Amps/2000-10/msg00359.html (7,920 bytes)
210. [AMPS] a sticky issue. (score: 1): Author: Peter_Chadwick@mitel.com (Peter Chadwick); Date: Mon, 16 Oct 2000 10:29:02 +0100; The suppressor coil wound with resistance wire has one advantage to my mind - it stays pretty much the same resistance over time; we know that carbon comp resistors do go go high. Even better is a la; /archives//html/Amps/2000-10/msg00364.html (8,386 bytes)
211. [AMPS] Tank circuit heating (score: 1): Author: Peter_Chadwick@mitel.com (Peter Chadwick); Date: Mon, 16 Oct 2000 11:43:43 +0100; There's been a fair bit of discussion on this, and Rich always suggests making sure that there's some extra cooling around the tank coil and the bandswitch. I've seen amplifiers where the 'cooling' w; /archives//html/Amps/2000-10/msg00366.html (7,605 bytes)
212. [AMPS] AMERITRON AL80A (score: 1): Author: Peter_Chadwick@mitel.com (Peter Chadwick); Date: Mon, 16 Oct 2000 13:33:39 +0100; Could someone explain how this can be so? Or perhaps the choke is supposed to be a series impedance at 60Hz, keeping the filament current and thus the emission, down? (No, I'm not serious!) 73 Peter; /archives//html/Amps/2000-10/msg00372.html (8,406 bytes)
213. [AMPS] 811A Plate Impedance? (score: 1): Author: Peter_Chadwick@mitel.com (Peter Chadwick); Date: Mon, 16 Oct 2000 13:37:30 +0100; So doubling the Q does not double the circulating current? 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@cont; /archives//html/Amps/2000-10/msg00373.html (7,463 bytes)
214. [AMPS] AMERITRON AL80A (score: 1): Author: Peter_Chadwick@mitel.com (Peter Chadwick); Date: Mon, 16 Oct 2000 16:05:53 +0100; If the inductance was insufficient, Dave, why should it affect the DC conditions? If the rewound choke had higher RESISTANCE, then it could caused increased bias - and lower filament voltage, which w; /archives//html/Amps/2000-10/msg00390.html (8,926 bytes)
215. [AMPS] AMERITRON AL80A (score: 1): Author: Peter_Chadwick@mitel.com (Peter Chadwick); Date: Tue, 17 Oct 2000 09:13:49 +0100; Well, the 3-500Z isn't that much bigger plate construction than the 4-400. In GG, with grid and screen grounded and 3600 on the plate, mine certainly glows under zero signal conditions at about 300 w; /archives//html/Amps/2000-10/msg00426.html (8,186 bytes)
216. [AMPS] Bird Wattmeters (score: 1): Author: Peter_Chadwick@mitel.com (Peter Chadwick); Date: Tue, 17 Oct 2000 09:27:15 +0100; For anyone interested, thanks to the help received here, the panel is finished. An 8 inch panel, a two hole Bird pick up line, and two meters fitted with Bird scales. Op amps to drive the meters, bec; /archives//html/Amps/2000-10/msg00427.html (7,680 bytes)
217. [AMPS] Screen protection WHAAAATTTTTT!!!! (score: 1): Author: Peter_Chadwick@mitel.com (Peter Chadwick); Date: Tue, 17 Oct 2000 09:28:20 +0100; Why not? 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com; /archives//html/Amps/2000-10/msg00428.html (8,187 bytes)
218. [AMPS] Screen protection WHAAAATTTTTT!!!! (score: 1): Author: Peter_Chadwick@mitel.com (Peter Chadwick); Date: Tue, 17 Oct 2000 09:30:58 +0100; So why use a 600volt rated FET? You can't get a 1500 volt rated FET? How about a glass encapsulated, hermetically sealed, hollow state FET capable of running high voltage, current and temperature - s; /archives//html/Amps/2000-10/msg00429.html (8,419 bytes)
219. [AMPS] Screen protection WHAAAATTTTTT!!!! (score: 1): Author: Peter_Chadwick@mitel.com (Peter Chadwick); Date: Tue, 17 Oct 2000 10:13:11 +0100; If the dissipation is going to be high in the dropper, a constant current source feeding the shunt screen regulator from a lower voltage can have the same effect. The current can be set to the maximu; /archives//html/Amps/2000-10/msg00430.html (9,371 bytes)
220. [AMPS] Screen protection WHAAAATTTTTT!!!! (score: 1): Author: Peter_Chadwick@mitel.com (Peter Chadwick); Date: Tue, 17 Oct 2000 12:18:50 +0100; an If there's no negative screen current, then you can get away without a shunt screen supply, admittedly. But you made a blanket, general staement. There are ways of shunt and series regulating at v; /archives//html/Amps/2000-10/msg00434.html (8,677 bytes)

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