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301. [Amps] RF In the Shack, and Antennas (score: 1)
Author: Jim Brown <jim@audiosystemsgroup.com>
Date: Tue, 05 Apr 2011 10:01:23 -0700
Sam, There are at least a half dozen interesting antenna concepts in your post. The "RF in the shack" part of the problem can be solved by more effectively de-coupling your feedlines with very good c
/archives//html/Amps/2011-04/msg00179.html (13,255 bytes)

302. Re: [Amps] 4 wire 240VAC service? What to do now? (score: 1)
Author: Jim Brown <jim@audiosystemsgroup.com>
Date: Tue, 05 Apr 2011 10:05:09 -0700
Remember that this is what I described as Method #2. Method #1 allows bonding neutral in the second building with no ground between buildings. 73, Jim K9YC ___________________________________________
/archives//html/Amps/2011-04/msg00180.html (10,670 bytes)

303. Re: [Amps] 4 wire 240VAC service? What to do now? (score: 1)
Author: Jim Brown <jim@audiosystemsgroup.com>
Date: Tue, 05 Apr 2011 21:26:39 -0700
It's in my NEC book. Don't recall the year, but not that old. Jim _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/am
/archives//html/Amps/2011-04/msg00205.html (10,311 bytes)

304. Re: [Amps] Where is power measured ? (score: 1)
Author: Jim Brown <jim@audiosystemsgroup.com>
Date: Thu, 07 Apr 2011 10:10:22 -0700
The current FCC is a bad joke. There's a station near me that's licensed for a 3-tower DA. They're only driving one of them, running Non-Dir. But they bought another station, and are running that sta
/archives//html/Amps/2011-04/msg00287.html (9,948 bytes)

305. Re: [Amps] Where is power measured ? (score: 1)
Author: Jim Brown <jim@audiosystemsgroup.com>
Date: Thu, 07 Apr 2011 10:24:38 -0700
Good question. When I lived in Chicago, I heard occasional mixes that I'm pretty sure were NOT generated at any of the stations involved. They came and went as if switched at random times, and not at
/archives//html/Amps/2011-04/msg00288.html (9,625 bytes)

306. Re: [Amps] DIN vs N (score: 1)
Author: Jim Brown <jim@audiosystemsgroup.com>
Date: Mon, 25 Apr 2011 16:20:57 -0700
I wouldn't blame this on the cell phone industry -- you just got suckered by JUNK connectors. Don't feel like the Lone Ranger -- I did too, buying a bunch at hamfests about 8 years ago. Caused me no
/archives//html/Amps/2011-04/msg00527.html (8,347 bytes)

307. Re: [Amps] 4-400A ratings (score: 1)
Author: Jim Brown <jim@audiosystemsgroup.com>
Date: Mon, 09 May 2011 08:51:50 -0700
It's when your signal is on the edge of the other guy's noise that small increases matter. Several years ago, I went through the process of squeezing a few extra dB out of my antenna system, raising
/archives//html/Amps/2011-05/msg00017.html (8,215 bytes)

308. Re: [Amps] T-T Titan with Pro III Question (score: 1)
Author: Jim Brown <jim@audiosystemsgroup.com>
Date: Thu, 26 May 2011 17:38:32 -0700
The control inputs of the Titan 425 are the base of a chip that you pull to ground to put in TX mode. It draws VERY little current, and it's not bitchy about how good the pull to ground is. You can d
/archives//html/Amps/2011-05/msg00247.html (9,544 bytes)

309. Re: [Amps] Titan 425 power transformer question (score: 1)
Author: Jim Brown <jim@audiosystemsgroup.com>
Date: Tue, 07 Jun 2011 14:41:32 -0700
YES! You'll also be getting reports of hum (or a buzzy CW note). Don't try testing by voltage measurements. You need an old fashioned analog VOM, like a Simpson 260 or even a cheaper equivalent. Let
/archives//html/Amps/2011-06/msg00090.html (8,306 bytes)

310. Re: [Amps] Ferrite toroids (score: 1)
Author: Jim Brown <jim@audiosystemsgroup.com>
Date: Fri, 26 Aug 2011 11:58:57 -0700
DANGER, WILL ROBINSON! Ferrite materials have VERY different characteristics as a function of frequency. This simple-minded sort of procedure only tells you about the low frequency behavior of the co
/archives//html/Amps/2011-08/msg00194.html (8,227 bytes)

311. Re: [Amps] RF on audio using 374A (score: 1)
Author: Jim Brown <jim@audiosystemsgroup.com>
Date: Tue, 13 Sep 2011 14:39:48 -0700
The problem is almost certainly at the Flex, and I'm guessing that the difference is the additional power of the larger amp. Assume a Pin One problem at the Flex, and add multi-turn ferrite chokes to
/archives//html/Amps/2011-09/msg00072.html (7,799 bytes)

312. Re: [Amps] RF on audio using 374A (score: 1)
Author: Jim Brown <jim@audiosystemsgroup.com>
Date: Wed, 14 Sep 2011 08:25:44 -0700
Ah, but it most likely WAS a Pin One Problem, and the choke to keep RF off the line was the easiest fix. Think, Carl, about HOW the RF on the coax shield gets into the equipment! The way equipment is
/archives//html/Amps/2011-09/msg00096.html (8,140 bytes)

313. Re: [Amps] RF on audio using 374A (score: 1)
Author: Jim Brown <jim@audiosystemsgroup.com>
Date: Wed, 14 Sep 2011 09:27:55 -0700
A balanced input is no cure for a Pin One Problem -- indeed, the entire concept of a Pin One Problem was first observed and identified by Neil Muncy, ex-W3WJE, with BALANCED inputs of pro audio gear.
/archives//html/Amps/2011-09/msg00099.html (8,980 bytes)

314. Re: [Amps] RF on audio using 374A (score: 1)
Author: Jim Brown <jim@audiosystemsgroup.com>
Date: Wed, 14 Sep 2011 13:34:33 -0700
You would likely change your mind (assuming it is still open for change) if you took the time to read the extensive documentation of it, some of which is on my website. It is a very clear concept, ea
/archives//html/Amps/2011-09/msg00106.html (8,646 bytes)

315. Re: [Amps] RF on audio using 374A (score: 1)
Author: Jim Brown <jim@audiosystemsgroup.com>
Date: Thu, 15 Sep 2011 10:36:57 -0700
That's a VERY optimistic assumption. :) Virtually all computer gear, ham gear, and consumer audio gear is built with Pin One Problems. Before Neil Muncy published his work, so did almost all pro gear
/archives//html/Amps/2011-09/msg00111.html (10,344 bytes)

316. Re: [Amps] RF in the Audio (score: 1)
Author: Jim Brown <jim@audiosystemsgroup.com>
Date: Fri, 23 Sep 2011 14:38:26 -0700
It is generally a good thing to seriously choke all feedlines to keep common mode RF off of them. Not only does common mode current conduct into the shack and excite Pin One problems like you have de
/archives//html/Amps/2011-09/msg00155.html (7,859 bytes)

317. Re: [Amps] RF in the Audio (score: 1)
Author: Jim Brown <jim@audiosystemsgroup.com>
Date: Fri, 23 Sep 2011 15:27:53 -0700
Wind a bifilar choke using 12-14 bifilar turns of #12 THHN on a #31 2.4-in o.d. toroid. It introduces a small mismatch (Zo approx 100 ohms), but only about two feet of line. Photos and details in the
/archives//html/Amps/2011-09/msg00157.html (7,080 bytes)

318. Re: [Amps] RF in the Audio (score: 1)
Author: Jim Brown <jim@audiosystemsgroup.com>
Date: Fri, 23 Sep 2011 18:50:23 -0700
You may not have heard about the concept, but it works quite well. DX Engineering has done similar things, but don't publish it. I've done considerable work on the topic, and published both the theor
/archives//html/Amps/2011-09/msg00159.html (7,813 bytes)

319. Re: [Amps] RF in the Audio (score: 1)
Author: Jim Brown <jim@audiosystemsgroup.com>
Date: Sat, 24 Sep 2011 08:18:22 -0700
If you think there's a difference between theory and practice, you don't know enough about one or the other. 73, Jim K9YC _______________________________________________ Amps mailing list Amps@contes
/archives//html/Amps/2011-09/msg00162.html (7,645 bytes)

320. Re: [Amps] RF in the Audio (score: 1)
Author: Jim Brown <jim@audiosystemsgroup.com>
Date: Sat, 24 Sep 2011 13:50:16 -0700
MANY of the DX Engineering so-called baluns are common mode chokes -- indeed, what is commonly called a "current balun" IS a common mode choke. Many DXE baluns that transform impedance are ARRAYS of
/archives//html/Amps/2011-09/msg00171.html (10,771 bytes)

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