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References: [ +from:4cx250b@miamioh.edu: 327 ]

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121. Re: [Amps] Topband: AC line bypass capacitors (score: 1): Author: "Jim Garland" <4cx250b@miamioh.edu>; Date: Wed, 4 Feb 2015 12:49:14 -0700; Yes, there are now standard bypass caps rated specifically for bypassing the AC line. There are two basic types, called X1 and Y2. They're made by numerous manufacturers. Here's a link to the ones I; /archives//html/Amps/2015-02/msg00054.html (7,977 bytes)
122. Re: [Amps] more - oil bath GS-35b (score: 1): Author: MU 4CX250B <4cx250b@miamioh.edu>; Date: Wed, 1 Apr 2015 11:22:14 -0600; I haven't thought about this deeply, but I'm thinking the rate of heat transfer to the oil bath depends only on the temperature difference between the oil (adjacent to the tube anode) and the anode t; /archives//html/Amps/2015-04/msg00010.html (10,445 bytes)
123. Re: [Amps] Time for New Power Meter (score: 1): Author: "Jim Garland" <4cx250b@miamioh.edu>; Date: Wed, 22 Apr 2015 09:32:09 -0600; Don, how do you know the LP-100A is the more accurate of the two? 73, Jim W8ZR Telepost Inc. would not hesitate wrote: _______________________________________________ Amps mailing list Amps@contestin; /archives//html/Amps/2015-04/msg00153.html (11,916 bytes)
124. Re: [Amps] Time for New Power Meter (score: 1): Author: "Jim Garland" <4cx250b@miamioh.edu>; Date: Sun, 3 May 2015 07:22:33 -0600; Joe and Roger are correct about Bird Wattmeter accuracy. It's 5% of full scale. I've not been following this thread closely, so I apologize if I'm duplicating what others have said, but I find the on; /archives//html/Amps/2015-05/msg00021.html (11,488 bytes)
125. [Amps] W8ZR QSK Circuit (score: 1): Author: "Jim Garland" <4cx250b@miamioh.edu>; Date: Wed, 6 May 2015 06:26:53 -0600; Hi All, I designed a QSK amplifier keying circuit last year for a homebrew amplifier, and QST is publishing a writeup on the design in this month's (June') QST. If you're interested, you can read an; /archives//html/Amps/2015-05/msg00090.html (7,208 bytes)
126. Re: [Amps] Looking for a 68pF 7KV HEC doorknob (score: 1): Author: "Jim Garland" <4cx250b@miamioh.edu>; Date: Fri, 22 May 2015 18:24:54 -0600; Gary, I've been out of town and just returned. I checked my doorknob inventory and have a 63pF/4500V, 5 % tolerance doorknob cap, made by Jennings. It looks just like the Centralab common 858 series,; /archives//html/Amps/2015-05/msg00166.html (10,284 bytes)
127. Re: [Amps] Fan for SB220 (score: 1): Author: "Jim Garland" <4cx250b@miamioh.edu>; Date: Mon, 8 Jun 2015 18:19:17 -0600; Sorry Adrian, but I respectfully disagree with your perceived "flaw" in my reasoning. (When did I post that, anyway? Don't remember doing it!) A "blackbody" (one word) is a well-understood physics co; /archives//html/Amps/2015-06/msg00011.html (11,279 bytes)
128. Re: [Amps] Regulated filament current (score: 1): Author: MU 4CX250B <4cx250b@miamioh.edu>; Date: Thu, 3 Sep 2015 17:00:10 -0600; Bob, If I understand your question, you want to feed the filament of your GS35b with a current source, rather than a voltage source. On the face of it, that seems like an unorthodox thing to do, sinc; /archives//html/Amps/2015-09/msg00005.html (8,479 bytes)
129. Re: [Amps] Regulated filament current (score: 1): Author: "Jim Garland" <4cx250b@miamioh.edu>; Date: Thu, 3 Sep 2015 21:46:14 -0600; I'm still a bit uncertain whether Bob W4OAS is speaking about a constant current power supply, or a constant voltage power supply which has current limiting. They're very different creatures, but as; /archives//html/Amps/2015-09/msg00007.html (10,798 bytes)
130. Re: [Amps] vacuum relay (score: 1): Author: MU 4CX250B <4cx250b@miamioh.edu>; Date: Tue, 8 Sep 2015 21:17:13 -0600; DPDT vacuum relays are unusual and typically sell for about $150, if you can find one. Nearly all of them have 26.5V coils. Most are made by Kilovac and Jennings, in my experience. If you can't find; /archives//html/Amps/2015-09/msg00030.html (7,402 bytes)
131. Re: [Amps] Alpha 76 question (score: 1): Author: MU 4CX250B <4cx250b@miamioh.edu>; Date: Tue, 24 Nov 2015 09:51:55 -0700; I have an Alpha 76 that I converted to 6 m years ago, which exhibited the same symptoms. The problem was internal arcing in one of the elderly electrolytic capacitors in the power supply. I ended up; /archives//html/Amps/2015-11/msg00152.html (8,986 bytes)
132. Re: [Amps] Need for bias switch (CW/SSB) (score: 1): Author: "Jim Garland" <4cx250b@miamioh.edu>; Date: Tue, 12 Jan 2016 08:48:13 -0700; Charlie, With an 8877, two bias settings aren't necessary. You'd gain a bit more efficiency on CW and slightly ower heat dissipation in the room, but that's about all. It's pretty important with tetr; /archives//html/Amps/2016-01/msg00004.html (8,709 bytes)
133. Re: [Amps] NCL-2000 (score: 1): Author: MU 4CX250B <4cx250b@miamioh.edu>; Date: Sat, 23 Jan 2016 08:36:03 -0700; A good source of HV wire is silicone test lead wire, available from MCMelectronics.com. It's about 1/8 in diameter, comes in red and black, is extremely flexible, and is rated at 10kV. 73, Jim w8zr S; /archives//html/Amps/2016-01/msg00062.html (9,843 bytes)
134. Re: [Amps] NTC thermistors as soft start (score: 1): Author: MU 4CX250B <4cx250b@miamioh.edu>; Date: Tue, 2 Feb 2016 09:40:25 -0600; It's true that the resistance of inrush current limiters varies with the load, but the time constant is long, 30 seconds or longer, for the resistance to return to the initial cold value. They work f; /archives//html/Amps/2016-02/msg00016.html (11,188 bytes)
135. Re: [Amps] 8877 heater inrush (score: 1): Author: "Jim Garland" <4cx250b@miamioh.edu>; Date: Tue, 26 Apr 2016 14:28:35 -0600; Alan, I wonder if you've considered using an inrush current limiter on either the primary or secondary side of your filament transformer? For the secondary side, the NTC B57127P0100M301 (Digi-key pp/; /archives//html/Amps/2016-04/msg00048.html (10,184 bytes)
136. Re: [Amps] SELL: Mint Drake L4B amplifier Package (score: 1): Author: "Jim Garland" <4cx250b@miamioh.edu>; Date: Fri, 6 May 2016 10:39:32 -0600; Ron, how do you get "legal limit ++" out of an L4B? I've owned several of them and get only 1200-1300W output, measured on accurately calibrated wattmetes. My latest one has the same mods (new caps,; /archives//html/Amps/2016-05/msg00004.html (9,790 bytes)
137. Re: [Amps] Cooling 77SX (score: 1): Author: MU 4CX250B <4cx250b@miamioh.edu>; Date: Fri, 6 May 2016 16:18:15 -0600; Hi Gary, The 77D and 77SX use a lovely mil spec Rotron blower. I've used the same model blower in a homebrew 8877 amp for thirty years and would love to find another one. Unfortunately, the blower us; /archives//html/Amps/2016-05/msg00011.html (9,416 bytes)
138. Re: [Amps] Alpha 77DX (score: 1): Author: MU 4CX250B <4cx250b@miamioh.edu>; Date: Tue, 17 May 2016 13:04:05 -0600; Lou, do you get any grid current and plate current? And I assume you've got HV. How about input VSWR? Shouldn't be a hard problem to diagnose. 73, Jim W8ZR Sent from my iPhone _______________________; /archives//html/Amps/2016-05/msg00029.html (7,492 bytes)
139. Re: [Amps] Acom 2000A - typical output power? (score: 1): Author: MU 4CX250B <4cx250b@miamioh.edu>; Date: Wed, 14 Sep 2016 11:29:09 -0600; The Alpha 9500 comes with somewhat noisy Gigavac vacuum relays. It's very easy to retrofit them with Jennings RJ1a relays, which are very quiet, have no contact bounce, and are faster. Ive done the c; /archives//html/Amps/2016-09/msg00045.html (11,448 bytes)
140. Re: [Amps] Acom 2000A - typical output power? (score: 1): Author: MU 4CX250B <4cx250b@miamioh.edu>; Date: Sat, 17 Sep 2016 18:59:54 -0600; The two Alpha 9500s I worked on each had two Gigavac G41C relays. They're fine, rugged relays, rated at higher power than the RJ1A, but are significantly noisier and slower (5uS typ). The relays I te; /archives//html/Amps/2016-09/msg00091.html (11,256 bytes)

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