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181. [Amps] Alpha 77Dx Filament Mod (Epilougue) (score: 1)
Author: "Paul Christensen" <w9ac@arrl.net>
Date: Sat, 7 Feb 2009 19:42:40 -0500
Just received my new 8877 and thought I would share with the group the final outcome of my results. Recall in prior postings that my intent for the Alpha 77Dx modification was to: (1) un-ground the f
/archives//html/Amps/2009-02/msg00184.html (7,356 bytes)

182. Re: [Amps] High SWR (score: 1)
Author: "Paul Christensen" <w9ac@arrl.net>
Date: Thu, 23 Apr 2009 09:47:38 -0400
Like their RG-8M class of cable they've sold since ca. 1981? I just conducted a search and they still sell it -- only it seems to be limited to a 10-foot jumper cable product rather than large spool
/archives//html/Amps/2009-04/msg00251.html (10,213 bytes)

183. Re: [Amps] High SWR (score: 1)
Author: "Paul Christensen" <w9ac@arrl.net>
Date: Thu, 23 Apr 2009 12:44:01 -0400
I think the importance VSWR in HF multiband operation lies somewhere in between extreme views. I need to know three things before I become worried about VSWR: (1) line characteristic Z; (2); the mat
/archives//html/Amps/2009-04/msg00268.html (9,697 bytes)

184. Re: [Amps] High SWR, (score: 1)
Author: "Paul Christensen" <w9ac@arrl.net>
Date: Thu, 23 Apr 2009 13:30:26 -0400
Agreed, Jim. But I would take exception to "power at any point on a transmission line." Part of the problem as I see it stems from viewing reflected power as a "thing" that reflects. Reflected power
/archives//html/Amps/2009-04/msg00272.html (9,671 bytes)

185. Re: [Amps] High SWR (score: 1)
Author: "Paul Christensen" <w9ac@arrl.net>
Date: Thu, 23 Apr 2009 13:55:47 -0400
VSWR in broadcasting applications is especially a concern when complex modulation schemes are used. FM stereophonic separation is highly dependent on line VSWR. Line reflections degrade stereo perfo
/archives//html/Amps/2009-04/msg00275.html (8,151 bytes)

186. Re: [Amps] High SWR (score: 1)
Author: "Paul Christensen" <w9ac@arrl.net>
Date: Thu, 23 Apr 2009 14:31:07 -0400
VSWR has been an obsession at least since the advent of Lew McCoy's Monimatch. For League members: http://tinyurl.com/c3ru92 http://tinyurl.com/dy84pw I wasn't around then, but I figure coax must ha
/archives//html/Amps/2009-04/msg00281.html (8,315 bytes)

187. Re: [Amps] Junk Connectors (score: 1)
Author: "Paul Christensen" <w9ac@arrl.net>
Date: Thu, 23 Apr 2009 15:31:44 -0400
Same here. For low/medium power, I'm using crimped silver-plated BNC connectors from either Amphenol or RF Industries. I've also standardized on RG-400 for all station interconnect cables less than
/archives//html/Amps/2009-04/msg00285.html (9,198 bytes)

188. Re: [Amps] Junk Connectors (score: 1)
Author: "Paul Christensen" <w9ac@arrl.net>
Date: Thu, 23 Apr 2009 18:41:43 -0400
I recently purchased a set of Amphenol "N" to SO-239 adapters. The loss of quality was very apparent versus the same product purchased ten years prior. The quality was so inferior, that I had to go
/archives//html/Amps/2009-04/msg00296.html (10,081 bytes)

189. Re: [Amps] DEAD Alpha 91B (score: 1)
Author: "Paul Christensen" <w9ac@arrl.net>
Date: Mon, 18 May 2009 13:06:24 -0400
As I recall, some of the old Henry amps used chassis ground as a neutral as well. On the Alpha 70 and 77 series, the fix to the amp is easy and doesn't even require turning a single cabinet screw. N
/archives//html/Amps/2009-05/msg00109.html (8,776 bytes)

190. Re: [Amps] DEAD Alpha 91B (score: 1)
Author: "Paul Christensen" <w9ac@arrl.net>
Date: Mon, 18 May 2009 14:34:11 -0400
Phil: My line voltage runs 255VAC and after two 8877 replacements in three years, I began to take this a bit more seriously. When I made the RFC mod, everything is easily reversible if someone wante
/archives//html/Amps/2009-05/msg00112.html (9,324 bytes)

191. Re: [Amps] Alpha 77 blower (score: 1)
Author: "Paul Christensen" <w9ac@arrl.net>
Date: Thu, 21 May 2009 06:57:18 -0400
Jim, Back in the early '90s, I serviced the bearings on a 77Dx blower. It was not difficult and as I recall, it uses a standard bearing. I purchased mine through a local industrial bearing supplier
/archives//html/Amps/2009-05/msg00148.html (7,033 bytes)

192. Re: [Amps] Checking relay timing with a scope (score: 1)
Author: "Paul Christensen" <w9ac@arrl.net>
Date: Sat, 20 Jun 2009 16:12:08 -0400
Pete: Here's a method I use to ensure proper amp relay sequencing: First, I utilize a dual trace scope (Tektronix SC 504). Channel 1 is DC-coupled and is used to monitor the amp key line closure, an
/archives//html/Amps/2009-06/msg00084.html (9,756 bytes)

193. Re: [Amps] Checking relay timing with a scope (score: 1)
Author: "Paul Christensen" <w9ac@arrl.net>
Date: Sat, 20 Jun 2009 16:12:12 -0400
_______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
/archives//html/Amps/2009-06/msg00085.html (8,101 bytes)

194. Re: [Amps] Grounded Grid (Screen) 4CX250B power gain (score: 1)
Author: "Paul Christensen" <w9ac@arrl.net>
Date: Tue, 21 Jul 2009 14:11:56 -0400
I did a "double-take" the first time I had seen one since Tokyo Hy-Power is more commonly known as a SS amp manufacturer. What's really got me excited is the use of adaptive pre-distortion in the ne
/archives//html/Amps/2009-07/msg00240.html (8,952 bytes)

195. Re: [Amps] 240V Outlet (score: 1)
Author: "Paul Christensen" <w9ac@arrl.net>
Date: Sun, 9 Aug 2009 14:32:14 -0400
That's a problem and needs correction. It wasn't a safe design practice in 1955 and it's just as much a safety concern in 2009. Here's why: If the current-carrying neutral+ground lead faults with a
/archives//html/Amps/2009-08/msg00162.html (9,381 bytes)

196. Re: [Amps] 240V Outlet (score: 1)
Author: "Paul Christensen" <w9ac@arrl.net>
Date: Sun, 9 Aug 2009 15:12:36 -0400
Excellent advice. It's been a while since I've reviewed that section of the NEC, but I suspect over-sizing the wire size is fine, but I would never oversize the breaker current rating, nor would I o
/archives//html/Amps/2009-08/msg00166.html (9,022 bytes)

197. Re: [Amps] 240V Outlet (score: 1)
Author: "Paul Christensen" <w9ac@arrl.net>
Date: Sun, 9 Aug 2009 19:59:08 -0400
If I was pretty sure that my amp powering needs didn't change in the future and had no issue with a slightly more invasive approach to modifying the PS (versus lifting neutral from ground), I would
/archives//html/Amps/2009-08/msg00178.html (9,294 bytes)

198. Re: [Amps] 240V Outlet (score: 1)
Author: "Paul Christensen" <w9ac@arrl.net>
Date: Sun, 9 Aug 2009 20:26:35 -0400
Upgrading the breaker to 20A is not an issue with 12/2 w/Ground since it's rated for 120VAC/20A service. Myself, I would then upgrade the receptacle to one rated for 20A. The question is whether or
/archives//html/Amps/2009-08/msg00181.html (8,845 bytes)

199. Re: [Amps] 240V Outlet (score: 1)
Author: "Paul Christensen" <w9ac@arrl.net>
Date: Sun, 9 Aug 2009 20:33:41 -0400
I see where Jim Smith had answered the last sentence above with this... "True, but the NEC makes an exception for 15 ampere general purpose receptacles on a 20 ampere circuit." Paul, W9AC __________
/archives//html/Amps/2009-08/msg00184.html (8,883 bytes)

200. Re: [Amps] 240V Outlet (score: 1)
Author: "Paul Christensen" <w9ac@arrl.net>
Date: Mon, 10 Aug 2009 09:39:59 -0400
Right, as long as only the wiring is "super-sized" in that application But to Carl's point, if the 240VAC demand is > 20A, then pricing of 30A material goes up on a seemingly exponential curve. When
/archives//html/Amps/2009-08/msg00220.html (9,852 bytes)

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