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301. Re: [TenTec] [Fwd: Line Isolator Balun (sorta) question.] (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Sun, 08 Aug 2010 10:25:05 -0500
However, for the ferrite makers, its virtually always true that at HF a ferrite with permeability of 1200 has lots of resistive loss. And the distributors rate only on permeability, getting that resi
/archives//html/TenTec/2010-08/msg00064.html (11,253 bytes)

302. Re: [TenTec] [Fwd: Line Isolator Balun (sorta) question.] (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Sun, 08 Aug 2010 10:27:20 -0500
One has to take care that the added reactive impedance doesn't become series resonant with the available wire length. You wish to shift to a wire plus reactance that makes an odd multiple of a quarte
/archives//html/TenTec/2010-08/msg00065.html (13,226 bytes)

303. Re: [TenTec] [Fwd: Line Isolator Balun (sorta) question.] (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Sun, 08 Aug 2010 15:28:05 -0500
The benefits on receive are that they can reduce the noise picked up by the outside of the coax. That noise can come from the house, or the neighborhood, or a vertically polarized storm many miles aw
/archives//html/TenTec/2010-08/msg00073.html (14,369 bytes)

304. Re: [TenTec] Jupiter 538 always on transmit (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Sun, 08 Aug 2010 15:38:01 -0500
Then you have to open it up and by voltage checks, find out what is causing it to transmit. It could be many things: It could be that the transistor that supplies +TX has shorted. I could be that the
/archives//html/TenTec/2010-08/msg00075.html (9,518 bytes)

305. Re: [TenTec] OT: automotive lightning hit (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Sun, 08 Aug 2010 18:38:11 -0500
Several years ago KD9UD, Charlie Corcoran, took a direct hit on his 2m antenna. It was hard on the radio, and I don't remember what happened to the car. I recall the 2m antenna was shortened, and the
/archives//html/TenTec/2010-08/msg00080.html (9,853 bytes)

306. Re: [TenTec] [Fwd: Line Isolator Balun (sorta) question.] (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Mon, 09 Aug 2010 13:47:46 -0500
The classic three winding voltage baluns force balance, but that can be upset by the antenna not being quite balanced. The choke baluns allow floating without forced ground reference that often gives
/archives//html/TenTec/2010-08/msg00094.html (11,547 bytes)

307. Re: [TenTec] [Fwd: Line Isolator Balun (sorta) question.] (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Mon, 09 Aug 2010 13:51:09 -0500
And the feed line not leaving the antenna at exactly 90 degrees. That's what the choke balun is all about. 73, Jerry, K0CQ _______________________________________________ TenTec mailing list TenTec@c
/archives//html/TenTec/2010-08/msg00095.html (10,627 bytes)

308. Re: [TenTec] [Fwd: Line Isolator Balun (sorta) question.] (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Mon, 09 Aug 2010 18:29:24 -0500
With so few radio/tv makers in this country practically no distributors stock "radio" parts, only computer parts. A couple sunspot minimums ago (at the approach of that minimum), I took on the design
/archives//html/TenTec/2010-08/msg00102.html (13,226 bytes)

309. Re: [TenTec] Headphones for ORION I? (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Wed, 11 Aug 2010 19:35:42 -0500
And so the voltage swing is limited to keep from overdriving the low impedance heaphones. Sometimes a voltage step up or impedance match will get more signal to higher impedance headphones and that i
/archives//html/TenTec/2010-08/msg00126.html (9,592 bytes)

310. Re: [TenTec] Headphones for ORION I? (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Thu, 12 Aug 2010 04:12:34 -0500
Heil did the luncheon speech at Central States VHF Conference in St. Louis last month and to hear him talk he's the worlds best expert on audio bar absolutely none. And he's proud that he flunked out
/archives//html/TenTec/2010-08/msg00144.html (10,281 bytes)

311. Re: [TenTec] Headphones for ORION I? (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Thu, 12 Aug 2010 16:08:09 -0500
One solution I use for really noise free audio is posted at: http://www.geraldj.networkiowa.com/papers/speakerfilter.pdf This filter has selectable cut off frequencies and being passive and built for
/archives//html/TenTec/2010-08/msg00155.html (10,933 bytes)

312. Re: [TenTec] Headphones for ORION I? (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Thu, 12 Aug 2010 17:35:16 -0500
There are 9 pages of rotary switches in the Mouser catalog that arrived this morning. pages 1727 through 1735. A very suitable switch and box could be had for a few bucks in a serial or parallel 1 to
/archives//html/TenTec/2010-08/msg00160.html (13,662 bytes)

313. Re: [TenTec] Headphones for ORION I? (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Thu, 12 Aug 2010 19:31:38 -0500
Back when I designed that filter, the coils I used were fairly expensive, so I used the varying impedance to allow using the same coils for all the frequencies. Plus large value capacitors were not e
/archives//html/TenTec/2010-08/msg00163.html (14,153 bytes)

314. Re: [TenTec] Headphones for ORION I? (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Fri, 13 Aug 2010 21:03:12 -0500
Lots of active filters can do the filtering function, but DSP and switched capacitor filters do have some noisy artifacts left in the stop band and the audio output amp they require also tends to hav
/archives//html/TenTec/2010-08/msg00183.html (17,004 bytes)

315. Re: [TenTec] swr (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Sun, 15 Aug 2010 20:18:50 -0500
A series loading coil at the vertical base might do the job but only on 160m. You have 43 feet of vertical, and a quarter wave at 160 meters is about 120 feet, so you need a coil containing about 77
/archives//html/TenTec/2010-08/msg00194.html (11,119 bytes)

316. Re: [TenTec] swr (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Sun, 15 Aug 2010 21:02:56 -0500
That much coax, about a half wave with velocity factor included, moves the capacitive antenna to inductive and allows some sort of resonating with just a series capacitor at the tuner (away from the
/archives//html/TenTec/2010-08/msg00201.html (11,761 bytes)

317. Re: [TenTec] swr (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Mon, 16 Aug 2010 01:17:00 -0500
Try it. Yes,its not perfect, but its as close as computing the C of the short antenna and computing the inductance required, and then the coil dimensions and the computation took much less time. If t
/archives//html/TenTec/2010-08/msg00205.html (10,275 bytes)

318. Re: [TenTec] swr (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Mon, 16 Aug 2010 02:01:18 -0500
You could always try a Hygain AV-6110 for $250 bucks. Grabbing my handy Lightning Calculator copyright 1932, I see my coil would be about 300 microhenries and the few on line references about such a
/archives//html/TenTec/2010-08/msg00206.html (9,991 bytes)

319. Re: [TenTec] Test again (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Mon, 16 Aug 2010 21:15:25 -0500
In the user options for this list there is the option to select whether your posts are returned to you or are not returned. Go here and log in to get to those options. 73, Jerry, K0CQ _______________
/archives//html/TenTec/2010-08/msg00233.html (8,484 bytes)

320. Re: [TenTec] swr (score: 1)
Author: "Dr. Gerald N. Johnson" <geraldj@weather.net>
Date: Mon, 16 Aug 2010 21:18:44 -0500
A 43' vertical is a serious mismatch on 160 and 80, its too short, has a low radiation resistance and lots of reactance. That makes a tuner run a high loaded Q and have lots of circulating current in
/archives//html/TenTec/2010-08/msg00234.html (10,312 bytes)

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