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241. Re: [Amps] Tuned Input - IMD and efficiency (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Tue, 8 Aug 2006 18:30:09 -0400; If the cathode sees a high impedance on even harmonics, looking back at the input circuit, it rounds the transition between off and on. I can easily hurt efficiency by making the cathode see a high; /archives//html/Amps/2006-08/msg00306.html (11,120 bytes)
242. [Amps] Impedance meters and test sets (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Tue, 8 Aug 2006 21:49:10 -0400; <Also, concerning the so-called comparison by Coilcraft, I didn't want to sound biased so I did some research to prove my point. Will, It appears you are missing the entire point of the coilcraft art; /archives//html/Amps/2006-08/msg00314.html (12,317 bytes)
243. Re: [Amps] Tuned Input - IMD and efficiency (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Tue, 8 Aug 2006 21:51:08 -0400; I wonder why Eimac entered a marketing agreement with Richardsons. 73 Tom _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/li; /archives//html/Amps/2006-08/msg00315.html (9,448 bytes)
244. Re: [Amps] Tuned Input - IMD and efficiency (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Wed, 9 Aug 2006 10:25:15 -0400; Since the primary current path at low frequencies is through the copper, and the primary current path at the highest frequencies is through the parallel resistrance chaning the resistance of the con; /archives//html/Amps/2006-08/msg00335.html (8,377 bytes)
245. Re: [Amps] Spam from Members of this List ... (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Wed, 9 Aug 2006 12:06:31 -0400; I think what the moderator was talking about are members of this list who copy and save email addresses from the list and use them to send messages to list members in bulk. Good manners dictates not; /archives//html/Amps/2006-08/msg00346.html (9,133 bytes)
246. Re: [Amps] Tuned Input - IMD and efficiency (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Wed, 9 Aug 2006 13:26:17 -0400; I wouldn't take that number to the bank since the result would have to depend heavily on the impedance seen at the cathode, how the exciter behaves, and even cable lengths. It might be something tha; /archives//html/Amps/2006-08/msg00352.html (10,482 bytes)
247. Re: [Amps] crying abt spam (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Wed, 9 Aug 2006 17:31:00 -0400; 1.) Fisher always felt this list was a particular problem. He actually didn't like this list at all, but he also had a hands-off policy. 2.) I can guess where Rich is heading but the administrator c; /archives//html/Amps/2006-08/msg00364.html (7,899 bytes)
248. Re: [Amps] solid-state amp "suckout" (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Thu, 10 Aug 2006 19:12:12 -0400; I thought the same thing. The problem is the load impedance presented by the transformer is always frequency dependent. If it goes through a peak at a certain frequency, the PA can saturate easier.; /archives//html/Amps/2006-08/msg00390.html (7,207 bytes)
249. Re: [Amps] Checking for IMD (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Fri, 11 Aug 2006 15:46:39 -0400; You either need to run two radios through attenuators into a combiner and through a 50 ohm input class A amplifier into the amp (I use a class A 8877/3CX1500A7), or find a radio that by itself has -; /archives//html/Amps/2006-08/msg00412.html (8,725 bytes)
250. Re: [Amps] Checking for IMD (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Fri, 11 Aug 2006 16:32:19 -0400; One thing everyone needs to keep in mind is IMD products at one point can even cancel other IMD products produced at another point in the system. You don't necessarily get the worse case condition, y; /archives//html/Amps/2006-08/msg00414.html (10,046 bytes)
251. Re: [Amps] Checking for IMD (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Fri, 11 Aug 2006 17:08:25 -0400; That would require syllabic variations along with two tones. It isn't difficult to do that. Do you mean for hum and noise? 73 Tom _______________________________________________ Amps mailing list Am; /archives//html/Amps/2006-08/msg00417.html (9,422 bytes)
252. Re: [Amps] Checking for IMD (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Fri, 11 Aug 2006 19:13:21 -0400; When you use two RF sources the closest harmonic is twice the operating frequency, so it normally isn't an issue. 73 Tom _______________________________________________ Amps mailing list Amps@contes; /archives//html/Amps/2006-08/msg00421.html (9,518 bytes)
253. Re: [Amps] Checking for IMD (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Fri, 11 Aug 2006 19:18:20 -0400; Since the IMD can add or subtract with variations in power level, cable lengths, and other things I would think a person would want to know how much contribution the amplifier makes when determining; /archives//html/Amps/2006-08/msg00422.html (9,902 bytes)
254. Re: [Amps] Checking for IMD (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Fri, 11 Aug 2006 20:35:50 -0400; It depends on the transmitter. You'd have harmonics at 4000 and 5000Hz although down 40dB or more, so I wouldn't think it too bad unless a harmonics would blow through the filter and wind up on the; /archives//html/Amps/2006-08/msg00425.html (10,007 bytes)
255. Re: [Amps] Checking for IMD (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Sat, 12 Aug 2006 00:27:32 -0400; If you get an old analyzer be very careful. Even the better of the old analyzers, like the HP141, requires a narrow frequency range RF section to be useful. There are a lot of analyzers out there th; /archives//html/Amps/2006-08/msg00434.html (9,389 bytes)
256. Re: [Amps] Questions on hot switching 2700V B+ to a 3CX800 amp. (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Sat, 12 Aug 2006 12:55:05 -0400; Mike, How much power are the bleeders actually dissipating? Did you ever look at that? I'd know that first before planning anything. The things I'd learn are the power in bleeders, the power to run; /archives//html/Amps/2006-08/msg00446.html (8,718 bytes)
257. Re: [Amps] Checking for IMD (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Sat, 12 Aug 2006 21:09:11 -0400; I'm pretty sure that does not give you the average IM level Tony. I'll have to think about that a little bit more, but off the top it seems wrong because the meter on our receivers detects peaks, no; /archives//html/Amps/2006-08/msg00451.html (11,202 bytes)
258. Re: [Amps] Checking for IMD (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Sun, 13 Aug 2006 05:51:42 -0400; The important point is to know the flaws and keep the flaws of most receivers from being what we measure. You'd have to look at the adjacent channel IM characteristics of the receiver and know its S; /archives//html/Amps/2006-08/msg00457.html (10,505 bytes)
259. Re: [Amps] Checking for IMD (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Sun, 13 Aug 2006 15:02:30 -0400; It's certainly easy. Let's see. The frequency spread of IM is the difference of the two frequencies. So if we have speech (an ahhh won't work well to replicate real speech) we can consider the frequ; /archives//html/Amps/2006-08/msg00462.html (10,537 bytes)
260. Re: [Amps] Checking for IMD (score: 1): Author: "Tom W8JI" <w8ji@w8ji.com>; Date: Sun, 13 Aug 2006 23:16:49 -0400; The extremes of IM3 product are the *highest frequency transmitted* plus 2.7 kHz and the *lowest frequency transmitted* minus 2.7kHz. Consider a 7 MHz USB signal . The upper IM3 would be 7.003 plus; /archives//html/Amps/2006-08/msg00465.html (11,609 bytes)

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