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References: [ +from:dmills@exponent.myzen.co.uk: 26 ]

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1. Re: [Amps] New NXP BLF578XR 1200W LDMOS FET is "indestructible" (score: 1): Author: Dan Mills <dmills@exponent.myzen.co.uk>; Date: Sat, 23 Jul 2011 16:45:22 +0100; Yep, ask the Lasers community about that little gotcha. You think power FETs are a pain to cool, you want to try a high power laser diode bar array.... Not only are they temperature tuned to match th; /archives//html/Amps/2011-07/msg00279.html (9,900 bytes)
2. Re: [Amps] Any new tube research? (score: 1): Author: Dan Mills <dmills@exponent.myzen.co.uk>; Date: Sat, 20 Aug 2011 18:18:04 +0100; Agreed that FETs on a reasonable DC rail will likely become increasingly popular, but you forgot the major component count from your list of boxes: Solid state amps use low Q output networks requirin; /archives//html/Amps/2011-08/msg00107.html (8,445 bytes)
3. Re: [Amps] Can distilled water be used for a dummy load ?? (score: 1): Author: Dan Mills <dmills@exponent.myzen.co.uk>; Date: Tue, 29 Nov 2011 16:17:52 +0000; I would be careful, distilled (or more commonly DI) water is corrosive as hell, and will tend to pick up metal ions over time. We use it in the primary cooling loop of things like YAG lasers, but the; /archives//html/Amps/2011-11/msg00173.html (8,193 bytes)
4. Re: [Amps] IMD (score: 1): Author: Dan Mills <dmills@exponent.myzen.co.uk>; Date: Sat, 31 Dec 2011 22:34:17 +0000; If and only if, the bandwidth of the baseband signal fed to the modulator is band limited to the width of the main channel (Unless there is a RF BPF further up the chain limiting the transmitted band; /archives//html/Amps/2012-01/msg00004.html (7,938 bytes)
5. Re: [Amps] Length of coax from xcvr to amp affecting input swr. (score: 1): Author: Dan Mills <dmills@exponent.myzen.co.uk>; Date: Sat, 31 Dec 2011 22:46:33 +0000; The in band match may well be just fine, but any harmonic energy will be mismatched by the tuned input stage and will be reflected, upsetting the impedance seen by the rigs LPF at that harmonic in a; /archives//html/Amps/2012-01/msg00005.html (8,989 bytes)
6. Re: [Amps] IMD (score: 1): Author: Dan Mills <dmills@exponent.myzen.co.uk>; Date: Mon, 02 Jan 2012 18:16:50 +0000; It does not actually take much of a limiter, the expense in broadcast limiters is in getting as close to 100% mod as possible, which is actually a secondary consideration for us. A clipper made from; /archives//html/Amps/2012-01/msg00018.html (8,767 bytes)
7. Re: [Amps] IMD (score: 1): Author: Dan Mills <dmills@exponent.myzen.co.uk>; Date: Mon, 02 Jan 2012 18:26:13 +0000; I was assuming something basically designed to be linear..... I have actually been playing with a modulating power supply in a SSB rig using cartesian feedback to linearise the modulation response an; /archives//html/Amps/2012-01/msg00020.html (8,539 bytes)
8. Re: [Amps] IMD (score: 1): Author: Dan Mills <dmills@exponent.myzen.co.uk>; Date: Tue, 03 Jan 2012 00:23:39 +0000; The PM component can be ignored if the modulation bandwidth is very small compared to the RF frequency (Always the case in SSB), in which case the envelope is simply sqrt (I^2+ Q^2) which is trivial; /archives//html/Amps/2012-01/msg00051.html (12,095 bytes)
9. Re: [Amps] IMD (score: 1): Author: Dan Mills <dmills@exponent.myzen.co.uk>; Date: Tue, 03 Jan 2012 01:21:32 +0000; Bear in mind that a communications SSB rig is only a decade wide (300Hz to 3K give or take), and a square wave is odd harmonics, so at most you will fit a 300Hz fundamental, plus 4 harmonics, which i; /archives//html/Amps/2012-01/msg00052.html (9,777 bytes)
10. Re: [Amps] IMD (score: 1): Author: Dan Mills <dmills@exponent.myzen.co.uk>; Date: Sat, 07 Jan 2012 01:57:00 +0000; Which is a problem for the design of a band limited clipper, rather then anything unique to SSB. There are ways to design band limited limiters and clippers that do not overshoot and do stay within a; /archives//html/Amps/2012-01/msg00097.html (9,566 bytes)
11. Re: [Amps] IMD (score: 1): Author: Dan Mills <dmills@exponent.myzen.co.uk>; Date: Sun, 08 Jan 2012 22:01:26 +0000; Interesting. I have just been doing some modelling, and it transpires that the peaks in the RF envelope are (pretty much as expected) strictly limited to rf| < sqrt(I^2 + Q^2) where I and Q are the b; /archives//html/Amps/2012-01/msg00109.html (11,336 bytes)
12. Re: [Amps] IMD (score: 1): Author: Dan Mills <dmills@exponent.myzen.co.uk>; Date: Wed, 11 Jan 2012 01:40:31 +0000; I generated my square wave approximation in the obvious fashion (sum of series of sines), then stuffed it through a IIR hilbert transform (and appropriate delay) to get the I,Q pair, standard phasing; /archives//html/Amps/2012-01/msg00127.html (8,905 bytes)
13. Re: [Amps] IMD (score: 1): Author: Dan Mills <dmills@exponent.myzen.co.uk>; Date: Fri, 13 Jan 2012 00:12:31 +0000; Of course, which is what is required to generate an I/Q analytic pair. Thanks, better to avoid making a fool of myself before I commit code to hardware (And worse, RF to aerial). In C.... include <st; /archives//html/Amps/2012-01/msg00139.html (12,307 bytes)
14. Re: [Amps] 50 volt power supply (score: 1): Author: Dan Mills <dmills@exponent.myzen.co.uk>; Date: Sun, 05 Feb 2012 18:29:14 +0000; Ebay, used computer or telecom supplies. Usually 48 - 52V, and a few KW is quite common. There is a 48V HP server supply that is rated for 3KW, and usually goes for $50 or so that pretty much always; /archives//html/Amps/2012-02/msg00021.html (8,128 bytes)
15. Re: [Amps] Capacitors vs No Capacitors (score: 1): Author: Dan Mills <dmills@exponent.myzen.co.uk>; Date: Thu, 19 Apr 2012 22:47:55 +0100; If the rig was big enough to operate on three phase power then there would only have been about 30% ripple even without a cap in there, so I am not at all surprised that an FM TX would work without a; /archives//html/Amps/2012-04/msg00187.html (7,850 bytes)
16. Re: [Amps] Capacitors vs No Capacitors (score: 1): Author: Dan Mills <dmills@exponent.myzen.co.uk>; Date: Fri, 20 Apr 2012 01:03:29 +0100; Ick! Yea, brain fart on my part, you are of course correct, but in either case a FM set running from a three phase 6 pulse rectifier with no bulk supply filtering is clearly entirely possible. Regard; /archives//html/Amps/2012-04/msg00194.html (9,832 bytes)
17. Re: [Amps] Capacitors vs No Capacitors (score: 1): Author: Dan Mills <dmills@exponent.myzen.co.uk>; Date: Mon, 23 Apr 2012 20:57:19 +0100; The only gotcha is that that the 6 phase bridge needs two transformers, both with the same secondary voltage, but one setup for three phase star and one for three phase delta primaries (The phase shi; /archives//html/Amps/2012-04/msg00223.html (9,348 bytes)
18. [Amps] Why are we building amps rather then transmitters? (Tubes vs. Solid State) (score: 1): Author: Dan Mills <dmills@exponent.myzen.co.uk>; Date: Thu, 03 May 2012 21:37:43 +0100; This whole topic has got me thinking.... Given that small signal RF generation is pretty much a non issue these days, I have to ask why build amps intended to take a modulated RF signal at significan; /archives//html/Amps/2012-05/msg00129.html (9,633 bytes)
19. Re: [Amps] Why are we building amps rather then transmitters? (Tubes vs. Solid State) (score: 1): Author: Dan Mills <dmills@exponent.myzen.co.uk>; Date: Thu, 03 May 2012 23:03:53 +0100; I was thinking in terms of taking the data (possibly as ethernet frames) straight into a modest FPGA and then doing the upsample followed by cordic carrier generation thing in the gate array. Somethi; /archives//html/Amps/2012-05/msg00131.html (10,454 bytes)
20. Re: [Amps] Why are we building amps rather then transmitters? (Tubes vs. Solid State) (score: 1): Author: Dan Mills <dmills@exponent.myzen.co.uk>; Date: Thu, 03 May 2012 23:35:54 +0100; Yea, I know about the HPSDR project. AM is really the easy case as there is no phase modulation component, so EER is really simple and class E (as long as you don't want easy tuning across a wide ban; /archives//html/Amps/2012-05/msg00136.html (10,224 bytes)

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