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221. Re: [Amps] HV relay (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Fri, 05 Feb 2010 09:46:06 -0800
It's OK to put HV on the tube during the warmup time. What you don't want to do is ask it to draw plate current or generate power. A simple delay circuit that locks out TX is all you need. 73, Jim K9
/archives//html/Amps/2010-02/msg00119.html (7,329 bytes)

222. Re: [Amps] HV relay (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sat, 06 Feb 2010 09:39:18 -0800
This is also what Ten Tec does with the Titan 425, using tubes that also require 3 min warmup. Tubes last a LONG time if not mistreated. 73, Jim K9YC _______________________________________________ A
/archives//html/Amps/2010-02/msg00146.html (8,338 bytes)

223. Re: [Amps] Tentec Titan 425 (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sun, 07 Feb 2010 11:41:32 -0800
Greg, There were several versions of this amp, all "running mods" that made relatively minor changes. Adding the WARC bands was one of them. I have three of these amps, one without the WARC band mods
/archives//html/Amps/2010-02/msg00199.html (9,523 bytes)

224. Re: [Amps] OT - source of flooded coax? (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 09 Feb 2010 10:24:36 -0800
Yes. As I recall, it's a Commscope cable they're selling. About five years ago, I wanted to have RG6 in stock to rewire my home for FM and TV, and for other general uses. I bought 1,000 ft of a very
/archives//html/Amps/2010-02/msg00283.html (8,438 bytes)

225. Re: [Amps] EBM Fan (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Thu, 18 Feb 2010 08:52:59 -0800
There is nothing "non-ideal" about this -- it is a perfectly good way to operate a 120V fan from a 240 volt source. Many good power amps are built that way, including some Ten Tec and Alpha models. 7
/archives//html/Amps/2010-02/msg00520.html (7,365 bytes)

226. Re: [Amps] Step Start circuit - needed or not? (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 23 Feb 2010 21:20:38 -0800
On Tue, 23 Feb 2010 22:42:35 -0500, herzog@frontiernet.net@frontiernet.net wrote: We learned that in the pro audio world too, again with the power supplies for big power amps. If you've got a couple
/archives//html/Amps/2010-02/msg00710.html (7,843 bytes)

227. Re: [Amps] soft start, how to determine if needed? (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Wed, 24 Feb 2010 09:17:15 -0800
The power supply for the Ten Tec Titan 425 (1980 vintage) uses a 20 ohm 25W resistor in series with one side of the primary. I haven't one apart for a while, but I recall the relay contacts looking l
/archives//html/Amps/2010-02/msg00724.html (7,919 bytes)

228. Re: [Amps] 120 cycle hum from Henry 2K-4 (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Thu, 04 Mar 2010 08:43:56 -0800
Clarification. I can believe magnetic coupling as the cause of 60 Hz hum, but a connection to EARTH has NOTHING to do with magnetic coupling. Magnetic coupling requires a loop for current that couple
/archives//html/Amps/2010-03/msg00074.html (7,675 bytes)

229. Re: [Amps] coaxial stub on amplifier output (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sat, 03 Apr 2010 08:57:34 -0700
Yes. I'm currently working on a Q&A style tutorial on coax and stubs. The first draft is at http://audiosystemsgroup.com/Coax-Stubs.pdf Comments are appreciated. I would especially appreciate additio
/archives//html/Amps/2010-04/msg00034.html (8,475 bytes)

230. [Amps] Eimac YC-238 (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sat, 03 Apr 2010 09:08:26 -0700
I have come into a pair of these tubes, which appear to be private-labeled 3CX800A7s. They are obviously used. I stuck them in my Titan 425 to see how they work. They seem to need about half as much
/archives//html/Amps/2010-04/msg00036.html (7,214 bytes)

231. Re: [Amps] coaxial stub on amplifier output (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sat, 03 Apr 2010 11:25:23 -0700
Yes, the stub burns most of the harmonic power that hits it. While we talk about a "zero ohm load," it's really some fraction of an ohm depending on the loss in the coax used to make the stub, so the
/archives//html/Amps/2010-04/msg00050.html (8,613 bytes)

232. [Amps] GigaVac Relays (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Mon, 26 Apr 2010 10:40:29 -0700
In the past year or two, there have been questions about Gigavac relays and their reliability. Up to now, I've heard no assessments one way or the other. At the Visalia DX convention last weekend, I
/archives//html/Amps/2010-04/msg00656.html (6,928 bytes)

233. [Amps] (no subject) (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Fri, 07 May 2010 08:09:15 -0700
In cleaning out the estate of a local silent key, we've come across a bunch of antique tubes. Here's a list. 210 800 815 955 2C43 344A Western Electric 3C24 from 1944 CUE838 S200 Matsushita VT127A VT
/archives//html/Amps/2010-05/msg00090.html (7,384 bytes)

234. [Amps] Collectible and TX Tubes Looking for a Home (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Fri, 07 May 2010 08:19:12 -0700
Re-posting with a subject line. :) Sorry for the goof. In cleaning out the estate of a local silent key, we've come across a bunch of antique tubes. Here's a list. 210 800 815 955 2C43 344A Western E
/archives//html/Amps/2010-05/msg00091.html (7,163 bytes)

235. [Amps] Tubes (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Fri, 07 May 2010 17:51:13 -0700
The TX tubes are spoken for. Some of the "collector" tubes are still available. Thanks for all the responses. 73, Jim K9YC _______________________________________________ Amps mailing list Amps@conte
/archives//html/Amps/2010-05/msg00108.html (6,396 bytes)

236. Re: [Amps] What's the story on these companies? (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Tue, 11 May 2010 20:51:37 -0700
That company was related to Crown, the company that first made tape recorders for missionaries, and later expanded into excellent audio power amps. The factory was in Elkhart, IN. I've been both a cu
/archives//html/Amps/2010-05/msg00139.html (8,822 bytes)

237. Re: [Amps] Heath copyright (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Fri, 21 May 2010 10:51:29 -0700
YES! It may come as a surprise to some, but there are people who LIVE by creating things that we benefit from. Their income DEPENDS on receiving money from the sale of their work, whether it's writin
/archives//html/Amps/2010-05/msg00249.html (9,613 bytes)

238. [Amps] 4CX250B Ratings in Dentron Clipperton V (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Fri, 21 May 2010 11:15:47 -0700
I've just fired up a Dentron Clipperton V modified for 6M operation per Dentron instructions. It uses a single 4CX250B in Class AB2. The bias is adjustable, and the factory recommends 50mA plate curr
/archives//html/Amps/2010-05/msg00250.html (8,165 bytes)

239. Re: [Amps] Heath copyright (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Fri, 21 May 2010 13:13:18 -0700
But that's capitalism -- your position sounds like socialism to me. :) But that's not what we're talking about in the case of the Heath manual, which documents a product that they sold (and with it,
/archives//html/Amps/2010-05/msg00255.html (8,904 bytes)

240. Re: [Amps] 4CX250B Ratings in Dentron Clipperton V (score: 1)
Author: "Jim Brown" <jim@audiosystemsgroup.com>
Date: Sat, 22 May 2010 10:22:49 -0700
So if I watch the screen current, am I tuning for minimum? Do I need to watch grid current, or will that take care of itself if the screen current is right? Many thanks for all the great responses, b
/archives//html/Amps/2010-05/msg00299.html (8,072 bytes)

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