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381. Re: [Amps] Sad State of the Hobby (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Fri, 19 Jan 2018 19:03:27 +0000; Hi Lee, and all, we are in the same boat there... A friend of mine has been getting himself interested in building a super Full legal limit solid state amplifier. This evening I started researching t; /archives//html/Amps/2018-01/msg00093.html (15,007 bytes)
382. [Amps] LDMOSFET input impedance (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Sat, 27 Jan 2018 22:59:07 +0000; Hello, does anybody have any data about the input impedance of the MRF1K50N or any other broadly comparable LDMOSFET, at 30MHz and possibly below? The datasheets typically only give this data for som; /archives//html/Amps/2018-01/msg00141.html (6,502 bytes)
383. Re: [Amps] new 2200m/630m amplifier - distorted waveform output (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Sun, 27 May 2018 18:58:47 +0000; Roger, 1) When PTT is asserted (with no RF drive), which results in a relay applying the gate bias and doing the antenna change over, there is a turn on transient visible on an oscilloscope. There ar; /archives//html/Amps/2018-05/msg00031.html (17,226 bytes)
384. Re: [Amps] new 2200m/630m amplifier - distorted waveform output (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Mon, 28 May 2018 01:43:57 +0000; Roger, I will follow your advice and work on eliminating the turn-on transient. There are 56 Ohm gate resistors That's quite high for such large FETs. I would use much lower ones. Note that I'm assum; /archives//html/Amps/2018-05/msg00032.html (11,288 bytes)
385. Re: [Amps] new 2200m/630m amplifier - distorted waveform output (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Mon, 28 May 2018 17:05:48 +0000; Roger, I will try lower value gate resistors. That will also have the advantage that I will be able to drive to higher output on 160 I think. (My 1W drive is not sufficient on 160.) Ops... We have a; /archives//html/Amps/2018-05/msg00039.html (16,071 bytes)
386. Re: [Amps] MOSFET amp for 80 m (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Wed, 18 Jul 2018 19:49:26 +0000; Angel, you are forgetting that this is a push-pull amplifier. If the MOSFETs were perfect (zero saturation voltage), then the available voltage swing would be ą13.8V for each, which equals 9.76V RMS.; /archives//html/Amps/2018-07/msg00058.html (7,627 bytes)
387. Re: [Amps] MOSFET amp for 80 m (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Sat, 21 Jul 2018 17:40:35 +0000; Angel, I built your ESR meter last year, and right away, it allowed me to repair several SMPS I had collected over the years! Good! It's a really useful gadget. OK, since it is a push-pull, the calcu; /archives//html/Amps/2018-07/msg00067.html (19,718 bytes)
388. Re: [Amps] 47 Ohm 5 watt (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Wed, 08 Aug 2018 16:50:37 +0000; Joe, I hope someone has in their parts box. (2) 5 Watt 47 ohm non inductive resistors. Actually I do have a few, apparently metal oxide, but shipping them to you would cost more and take much longer; /archives//html/Amps/2018-08/msg00024.html (7,727 bytes)
389. Re: [Amps] 130 V MOV placement ?? (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Sat, 22 Sep 2018 18:19:15 +0000; Jim, IF using a 130 V rated MOV, where does it get wired ? Do you wire between 120 vac and neutral.... or 120 vac and chassis of equipment in question ? Between 120VAC phase and neutral. NOT to the c; /archives//html/Amps/2018-09/msg00026.html (10,569 bytes)
390. Re: [Amps] Solid state amp high SWR distortion (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Mon, 24 Sep 2018 18:04:14 +0000; John, I'm converting from a tube amp to a solid state amp. I've seen references to increased distortion caused by a solid state amp when the SWR is high, not high enough to cause reduced (foldback) p; /archives//html/Amps/2018-09/msg00033.html (11,720 bytes)
391. Re: [Amps] Flex Power Genius XL 2KW amplifier (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Mon, 08 Oct 2018 20:58:05 +0000; Considering how much care went into the design of the Flex amplifier, which in many ways is quite remarkable, it?s surprising how basic CW operation seems to have been shortchanged. Could it be that; /archives//html/Amps/2018-10/msg00027.html (10,400 bytes)
392. Re: [Amps] Flex Power Genius XL 2KW amplifier (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Thu, 11 Oct 2018 16:47:02 +0000; Tom, Just because you don't operate CW doesn't mean there isn't a market out there for a CW amplifier. I fully agree on that. The question is just how large that market is, compared to the market for; /archives//html/Amps/2018-10/msg00035.html (13,796 bytes)
393. Re: [Amps] Super Cathode Driven Tetrodes (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Mon, 29 Oct 2018 17:38:45 +0000; Bill, Can anyone give me a reason why a cathode driven tetrode with the control grid connected directly to the cathode be unstable. The screen grid is connected directly to ground. While I'm definite; /archives//html/Amps/2018-10/msg00108.html (10,036 bytes)
394. Re: [Amps] Fwd: Fwd: *** PGXL Questions on CW Operation (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Wed, 31 Oct 2018 19:41:07 +0000; Jim, interesting replies there. I would like to add some comments, for the possible benefit of readers: when using a Flex transceiver with the amp, there is no control cable between it and the transc; /archives//html/Amps/2018-11/msg00005.html (15,759 bytes)
395. [Amps] *** PGXL Questions on CW Operation (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Fri, 02 Nov 2018 18:46:32 +0000; Jim, other fellows transmissions, delayed or otherwise, so that you know you are ...doubling with him. That makes sense. Anyway I see two requirements for speed: One is to hear between dits, or at le; /archives//html/Amps/2018-11/msg00018.html (10,884 bytes)
396. Re: [Amps] Choke anomoly (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Sun, 11 Nov 2018 17:49:09 +0000; Jim, I measured the DC resistance, using my fluke 87..and it measured exactly 10.0 ohms. Then re-measured using my B+K 875-A... and it spits out 8.7 ohms. Such a big choke can easily fool a multimete; /archives//html/Amps/2018-11/msg00045.html (14,252 bytes)
397. [Amps] LDMOSFET questions for insiders (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Sat, 17 Nov 2018 18:48:09 +0000; Hello, is there anyone on this forum who knows LDMOSFETs really well and could answer a few questions? My questions refer to a high power device like the BLF188XR or the MRF1K50N, operating in a broa; /archives//html/Amps/2018-11/msg00057.html (8,616 bytes)
398. Re: [Amps] heat sinks (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Fri, 16 Nov 2018 20:39:45 +0000; Larry, my reply won't be the most helpful, but anyway: Make a highly efficient amplifier. Then you don't need a huge heatsink. Other than this, Heatsink USA is where I have bought heatsinks several t; /archives//html/Amps/2018-11/msg00058.html (7,907 bytes)
399. Re: [Amps] heat sinks (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Mon, 19 Nov 2018 14:45:10 +0000; Ron, With the high cost aluminum I can't help but wonder if something like copper sheeting could be used instead. (1/4" thick or so) Copper is nearly twice as good a thermal conductor as pure alumini; /archives//html/Amps/2018-11/msg00064.html (9,456 bytes)
400. Re: [Amps] LDMOSFET questions for insiders (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Mon, 19 Nov 2018 14:07:42 +0000; Doug, thanks for that link. What I take home from reading it is that I should expect a somewhat reduced total dissipation capability when avalanching is involved. But doubts remain as to whether that; /archives//html/Amps/2018-11/msg00065.html (8,578 bytes)

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