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221. Re: [Amps] grid resonance (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Fri, 4 Aug 2006 21:43:49 -0400
A series circuit can not do this and thus can not be measured by a GDO. You can rewire the series resonant circuit in any number of ways to make it into a parallel equivalent, but then you no longer
/archives//html/Amps/2006-08/msg00155.html (9,450 bytes)

222. Re: [Amps] Grid Vs cathode drive (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Fri, 4 Aug 2006 21:54:05 -0400
Someone earlier said that the FCC didn't screw the pooch when they did. When the law was changed, 11 meter amps were already a hot item, and the ones who thought up the rules ought to have had enough
/archives//html/Amps/2006-08/msg00156.html (8,745 bytes)

223. Re: [Amps] grid resonance (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Sat, 5 Aug 2006 05:43:48 -0400
So the loading coil is like a trap, and the coax sees an open circuit? The idea a GDO can sort "good resonances" that make low impedances from "bad resonances" that make high impedances seems pretty
/archives//html/Amps/2006-08/msg00176.html (10,241 bytes)

224. Re: [Amps] Ameritron Amps (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Sat, 5 Aug 2006 06:00:17 -0400
The only commercial amplifier using those tubes changed to a nichrome suppressor and continued to have the same problem with the same tube source. That means either the parasitic thing was wrong, or
/archives//html/Amps/2006-08/msg00177.html (9,163 bytes)

225. Re: [Amps] grid resonance (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Sat, 5 Aug 2006 08:13:06 -0400
I want to learn how to sort good parallel resonances from bad series-resonances and measure Q with mine! All mine seems to do is measure resonance, and it does not always do well at that. 73 Tom ___
/archives//html/Amps/2006-08/msg00179.html (9,825 bytes)

226. Re: [Amps] grid resonance (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Sat, 5 Aug 2006 10:16:30 -0400
Careful Peter! The next thing you will be telling us is the GDO won't measure Q or impedances, and then some might realize what a nice house of cards can be built by misusing or misunderstanding bas
/archives//html/Amps/2006-08/msg00184.html (8,264 bytes)

227. Re: [Amps] Grid Vs cathode drive (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Sat, 5 Aug 2006 13:30:44 -0400
160 meters had a power limit of 10 watts in most foreign countries. In the USA it changed over the years from a low of 25 watts on permitted segments to a high of 200 watts night power. It was only
/archives//html/Amps/2006-08/msg00190.html (11,647 bytes)

228. Re: [Amps] grid resonance (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Sat, 5 Aug 2006 13:40:50 -0400
The sharpness of the dip only gives an indication of the load impedance seen at the grid or gate. Distance, turns ratio between the oscillator coil and the DUT, and many other things determine dip d
/archives//html/Amps/2006-08/msg00192.html (10,489 bytes)

229. Re: [Amps] grid resonance (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Sat, 5 Aug 2006 13:52:07 -0400
"The Hewlett Packard HP4191A is emerging as the new standard for inductance measurements of RF coils. The HP4191A has an accuracy that can be better than 1%" I guess I won't be trading my 4191A in f
/archives//html/Amps/2006-08/msg00194.html (8,658 bytes)

230. Re: [Amps] grid resonance (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Sun, 6 Aug 2006 10:58:49 -0400
It's a general statement. A series resonant circuit doesn't change modes until the stray capacitance effectively shunting the inductor from end-to-end is equal to inductance. A short mobile antenna
/archives//html/Amps/2006-08/msg00208.html (8,460 bytes)

231. Re: [Amps] Ameritron Amps (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Sun, 6 Aug 2006 14:37:48 -0400
Almost all "problems" with dielectrics come from use in capacitors or insulation applications with concentrated electric fields in high-impedance areas. I can't understand why people seem to keep ri
/archives//html/Amps/2006-08/msg00223.html (9,184 bytes)

232. Re: [Amps] grid resonance (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Sun, 6 Aug 2006 14:51:23 -0400
When you include the car body, it is a parallel resonant circuit, not series. The whip is electromagnetically coupled to the car body and that makes it parallel resonant. >> What does that mean? Anyt
/archives//html/Amps/2006-08/msg00224.html (11,255 bytes)

233. Re: [Amps] Henry 2KD-5 120 Hz Hum (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Sun, 6 Aug 2006 15:50:33 -0400
Are you sure it is 120 Hz and not 60Hz? _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
/archives//html/Amps/2006-08/msg00227.html (6,470 bytes)

234. Re: [Amps] Henry 2KD-5 120 Hz Hum (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Sun, 6 Aug 2006 17:09:39 -0400
Sounds like a filament balance problem to me. 73 Tom _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
/archives//html/Amps/2006-08/msg00231.html (7,175 bytes)

235. Re: [Amps] grid resonance (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Sun, 6 Aug 2006 17:14:40 -0400
It the antenna's capacitance is indeed exclusively across the loading coil, we are in big trouble. We have lost all common mode currents and radiation resistance is zero. 73 Tom ____________________
/archives//html/Amps/2006-08/msg00232.html (9,877 bytes)

236. Re: [Amps] grid resonance (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Mon, 7 Aug 2006 16:42:49 -0400
Of course it is large enough to have resonances at frequencies we might be interested in. We not only have to contend with lead lengths there is also considerable capacitance, both distributed and l
/archives//html/Amps/2006-08/msg00267.html (9,401 bytes)

237. Re: [Amps] grid resonance (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Tue, 8 Aug 2006 05:57:19 -0400
You need to reread the article Wil. What they said and what you got from it are two totally different things. You also better look at how the equipment works before launching into oversimplification
/archives//html/Amps/2006-08/msg00282.html (12,057 bytes)

238. Re: [Amps] Tuned Input - IMD and efficiency (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Tue, 8 Aug 2006 11:50:49 -0400
I've never compared IM performance related to input circuits, but I have observed efficiency changes. A prototype (pair of 3-500Z amp) I built for Heath had horrible ten meter efficiency. It was in
/archives//html/Amps/2006-08/msg00293.html (11,398 bytes)

239. Re: [Amps] Tuned Input - IMD and efficiency (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Tue, 8 Aug 2006 12:41:02 -0400
Based on how the system works (as shown in changes in efficiency) it would depend on the exciter, cable lengths, and the impedance presented at the cathode. There can be cases where it doesn't chang
/archives//html/Amps/2006-08/msg00299.html (9,915 bytes)

240. Re: [Amps] grid resonance (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Tue, 8 Aug 2006 13:01:25 -0400
N7WS measured a nichrome suppressor and a regular suppressor and found no difference at all behavior at VHF. I've done the same. Nichrome causes the greatest Q change at the lowest frequency, and ha
/archives//html/Amps/2006-08/msg00301.html (9,313 bytes)

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