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141. [AMPS] AL1500 (score: 1): Author: Peter.Chadwick@zarlink.com (Peter Chadwick); Date: Thu, 6 Dec 2001 07:58:01 -0000; So you can with good tubes. There are many evidences of tubes such as klystrons in TV and radar service which have still met full spec after 120,000 operating hours. My 6L6 regulator tube still meets; /archives//html/Amps/2001-12/msg00139.html (11,845 bytes)
142. [AMPS] AL1500 (score: 1): Author: Peter.Chadwick@zarlink.com (Peter Chadwick); Date: Fri, 7 Dec 2001 07:58:05 -0000; If you use a resistor as a fuse, how do you guarantee the fusing characteristics (except for fusible resistors)? Even fusible resistors have enormous tolerances on them, while similar resistors from; /archives//html/Amps/2001-12/msg00156.html (8,047 bytes)
143. [AMPS] 4-400 amp (score: 1): Author: Peter.Chadwick@zarlink.com (Peter Chadwick); Date: Fri, 7 Dec 2001 08:54:24 -0000; My experience is that's a bit low for 4-400s, although it depends how much you expect out, while for CW, you don't need linearity. I'd go for passive grid with 100 watts drive: for 10 watts, you can; /archives//html/Amps/2001-12/msg00159.html (6,852 bytes)
144. [AMPS] FW: Dec 7th (score: 1): Author: Peter.Chadwick@zarlink.com (Peter Chadwick); Date: Fri, 7 Dec 2001 13:06:01 -0000; -- 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/2001-12/msg00160.html (7,214 bytes)
145. [AMPS] Rotary Inductors in Amps (score: 1): Author: Peter.Chadwick@zarlink.com (Peter Chadwick); Date: Thu, 13 Dec 2001 07:37:49 -0000; Additional to Dan's comments: I've seen an edge wound coil where the coil was fixed, and a central spindle carried a wiping arm. This had two large contact pads each side of the actual coil strip. Wo; /archives//html/Amps/2001-12/msg00215.html (7,652 bytes)
146. [AMPS] SB-200 & 10MHz (score: 1): Author: Peter.Chadwick@zarlink.com (Peter Chadwick); Date: Thu, 13 Dec 2001 13:24:38 -0000; I've done sums on pi networks for 10 and 14 MHz, which suggets you can do it OK. However, the technique is design for Q of about 13 at at the geometric average of the two frequencies, and then work b; /archives//html/Amps/2001-12/msg00218.html (7,808 bytes)
147. [AMPS] SB-200 & 10MHz++ (score: 1): Author: Peter.Chadwick@zarlink.com (Peter Chadwick); Date: Mon, 17 Dec 2001 07:44:38 -0000; How do you meet FCC Part 97.307(d) with such an arangement? In a class AB amplifier, the second harmonic component of plate current is 6dB down on fundamental, so you need another 34dB out of the tan; /archives//html/Amps/2001-12/msg00277.html (7,792 bytes)
148. [AMPS] Transformer Current ratings (score: 1): Author: Peter.Chadwick@zarlink.com (Peter Chadwick); Date: Mon, 17 Dec 2001 07:49:12 -0000; One other trick to check a transformer is to measure the resistance of the secondary winding. Then using a variac, connect an ammeter across the secondary, and wind up the primary volts until the sec; /archives//html/Amps/2001-12/msg00278.html (9,432 bytes)
149. [AMPS] Transformer Current ratings (score: 1): Author: Peter.Chadwick@zarlink.com (Peter Chadwick); Date: Mon, 17 Dec 2001 13:09:21 -0000; For finding the winding temperature rise at a given load, (which is the context for which this was suggested), it doesn't matter which winding resistance you measure. You are only interested in cold; /archives//html/Amps/2001-12/msg00282.html (9,103 bytes)
150. [AMPS] SB-200 & 10MHz++ (score: 1): Author: Peter.Chadwick@zarlink.com (Peter Chadwick); Date: Mon, 17 Dec 2001 14:13:37 -0000; So what? The amplifiers have Pi-L networks, and the tuner the T network. Going to a straight pi network in the amplifier and no tuner is going to reduce the overall harmonic suppression. Interestingl; /archives//html/Amps/2001-12/msg00285.html (7,525 bytes)
151. [AMPS] SB-200 & 10MHz++ (score: 1): Author: Peter.Chadwick@zarlink.com (Peter Chadwick); Date: Mon, 17 Dec 2001 14:35:02 -0000; Sorry Alex, don't quite follow you. Are you suggesting that I'm wondering why I didn't think about getting rid of the tuner and going to a pi tank instead of a Pi-L? If that is what you are suggesti; /archives//html/Amps/2001-12/msg00287.html (8,090 bytes)
152. [AMPS] Transformer Current ratings (score: 1): Author: Peter.Chadwick@zarlink.com (Peter Chadwick); Date: Mon, 17 Dec 2001 15:56:20 -0000; ??????????? What I'm suggesting is that a transformer can be checked for temperature rise at a given current by doing the short circuit test. This heats the windings because of the copper loss (i.e.; /archives//html/Amps/2001-12/msg00292.html (9,895 bytes)
153. [AMPS] Transformer Current ratings (score: 1): Author: Peter.Chadwick@zarlink.com (Peter Chadwick); Date: Wed, 19 Dec 2001 07:50:45 -0000; // What if said transformer is to be used for voice SSB? It's your decision on what temperature rise is acceptable under your the desired ratings. You decide on the ratings. Voice SSB can mean anythi; /archives//html/Amps/2001-12/msg00335.html (8,661 bytes)
154. [AMPS] Inductors (score: 1): Author: Peter.Chadwick@zarlink.com (Peter Chadwick); Date: Wed, 19 Dec 2001 08:17:17 -0000; Variometers were used a lot in 500kHz marine tx's. The big problem with them is at minimum inductance, where Lt = L1 - L2 - 2M, but R is the same. The Q gets a bit abysmal if you want a wide range. A; /archives//html/Amps/2001-12/msg00336.html (7,676 bytes)
155. [AMPS] Transformer Current ratings (score: 1): Author: Peter.Chadwick@zarlink.com (Peter Chadwick); Date: Thu, 20 Dec 2001 10:25:42 -0000; Careful, Rich, or he'll bad mouth you in his broadcasts, just as he did me! Incidentally, I don't understand how the FCC have let him back on. In many cases, I reckon that could well be the limiting; /archives//html/Amps/2001-12/msg00379.html (8,301 bytes)
156. FW: [AMPS] Bypassing Screen of 4cx800a for 50 MHz (score: 1): Author: Peter.Chadwick@zarlink.com (Peter Chadwick); Date: Thu, 20 Dec 2001 11:38:22 -0000; -- 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/2001-12/msg00382.html (12,918 bytes)
157. [AMPS] HV Pole Pig Transformers (score: 1): Author: Peter.Chadwick@zarlink.com (Peter Chadwick); Date: Thu, 20 Dec 2001 11:41:29 -0000; I thought the the term 'PCB' was supposed to automatically produce a major hysteric reaction? Jim's measured comments are very welcome. 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amp; /archives//html/Amps/2001-12/msg00383.html (8,350 bytes)
158. FW: [AMPS] Bypassing Screen of 4cx800a for 50 MHz (score: 1): Author: Peter.Chadwick@zarlink.com (Peter Chadwick); Date: Fri, 21 Dec 2001 07:26:51 -0000; I agree with that sentiment - even if you have a supply of free tubes! 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-; /archives//html/Amps/2001-12/msg00426.html (8,328 bytes)
159. [AMPS] 1.8kHz filters (score: 1): Author: Peter.Chadwick@zarlink.com (Peter Chadwick); Date: Fri, 21 Dec 2001 07:50:20 -0000; I got the 1.8kHz filter for the FT102 at the last Dayton. It's proved worth it on a few occasions, but only for getting the callsign and report through in bad conditions, not if you want to chat. In; /archives//html/Amps/2001-12/msg00427.html (6,727 bytes)
160. [AMPS] How to control a vacuum C ?? (score: 1): Author: Peter.Chadwick@zarlink.com (Peter Chadwick); Date: Thu, 1 Nov 2001 07:46:38 -0000; Stopping the motor can be done by dropping a short circuit (or, more kindly, a 5 to 10 ohm resistor) across it when the power is removed. This is the technique I use on my motor driven VVC's: however; /archives//html/Amps/2001-11/msg00005.html (7,468 bytes)

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