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321. Re: [Amps] Tubes, transistors, and 'abuse' (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Tue, 25 Apr 2017 19:51:55 +0000; Steve, It would also be interesting to get Manfred's views on the Hardrock 50: https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxoYXJkcm9jazUwYmV0YXxneDoxOGMwZTJiMDIzYjZmOWE Oh bo; /archives//html/Amps/2017-04/msg00280.html (17,094 bytes)
322. Re: [Amps] Price per Watt Conversation (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Tue, 25 Apr 2017 20:37:07 +0000; Jim, lousy imd, or better IMD and lousy 35% eff..take your pick. Yes. You see? That's why I think that we need to look forward, forget conventional old-fashioned class AB linear amplifiers, and devel; /archives//html/Amps/2017-04/msg00281.html (14,553 bytes)
323. Re: [Amps] Emergency communication (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Mon, 01 May 2017 18:59:53 +0000; Roger, and all, Without a lot of compression and clipping the duty cycle for SSB is only 20%. Given 100W out at 60% efficiency, we are looking at roughly 167W input at the 20% duty cycle or roughly 3; /archives//html/Amps/2017-05/msg00011.html (8,334 bytes)
324. Re: [Amps] Emergency communication (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Mon, 01 May 2017 19:12:07 +0000; Cathy, My K1 draws about 55 mA on receive and puts out 7 watts on transmit. Of course it's CW only. :-) Well, let me brag a little: My PQD5, homebrew in 1987, draws only 33mA on receive. And it's SSB; /archives//html/Amps/2017-05/msg00016.html (7,887 bytes)
325. Re: [Amps] Ham Tests, was Price per Watt Conversation (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Mon, 01 May 2017 19:22:11 +0000; Jim, a ten-tec hercules SS 500 watt amp. Transistors are un obtainium. There is no drop in replacement either. There is no way to even re-design and rebuild the damned thing. Its a door stop, worth n; /archives//html/Amps/2017-05/msg00018.html (8,675 bytes)
326. Re: [Amps] Efficient amplifier design (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Mon, 01 May 2017 19:38:02 +0000; Cathy, How much easier does the design become if we select an upper frequency bound of 15 MHz instead of 30 MHz? To give a simple-to-grasp figure, I would say it becomes roughly 3 times easier. That'; /archives//html/Amps/2017-05/msg00019.html (8,867 bytes)
327. Re: [Amps] Price per Watt Conversation (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Mon, 01 May 2017 20:08:32 +0000; Cathy, When we get to 3000V, we can have drop-in replacements for our tube amplifier finals! :-) That would be fun... :-) But not really practical. The high voltage needed for tubes is a nuisance rat; /archives//html/Amps/2017-05/msg00020.html (10,350 bytes)
328. Re: [Amps] High voltage MOSFETs (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Thu, 04 May 2017 23:29:59 +0000; Bill, One intriguing possibility with these is direct coupling (through an LP filter and DC isolation of course) to 50 ohm coax. Forget the low Q lowpass filter. This transistor is rated for 300pF ou; /archives//html/Amps/2017-05/msg00059.html (15,104 bytes)
329. Re: [Amps] High voltage MOSFETs (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Fri, 05 May 2017 22:17:37 +0000; Jim, of these proposed configurations ?? I have often tuned up solid state amps. While I have never so far seen one that has tune and load controls on the front panel, or anything like that, many sol; /archives//html/Amps/2017-05/msg00077.html (14,181 bytes)
330. Re: [Amps] HV MOSFETs for RF (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Fri, 05 May 2017 23:26:20 +0000; Cathy, To your list of other services needing linear amps you can add analog TV transmitters (where still used), digital TV transmitters, certain medical equipment, marine and aeronautical HF communi; /archives//html/Amps/2017-05/msg00079.html (11,168 bytes)
331. Re: [Amps] HV MOSFETs for RF (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Wed, 10 May 2017 16:17:26 +0000; Jim, main 100 watt pa need a serious re-design. What exactly would you improve in that design? I just had a look at those schematics. The driver section looks pretty OK to me, while the 100W amp suff; /archives//html/Amps/2017-05/msg00106.html (9,002 bytes)
332. Re: [Amps] HV MOSFETs for RF (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Thu, 11 May 2017 18:21:01 +0000; Kevin, I don't think so...! 12V 100W amplifiers do have their place - in mobile rigs. Although nowadays it does make sense to use a DC-DC converter to raise the 12V to something more convenient, the; /archives//html/Amps/2017-05/msg00114.html (12,298 bytes)
333. Re: [Amps] HV MOSFETs for RF (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Fri, 12 May 2017 02:09:05 +0000; Cathy, What is that flaw in most 100W radios, Manfred? It's the lack of coupling between the two sides (the two drains, or collectors) of the push-pull stage. In linear class AB or B push-pull stages; /archives//html/Amps/2017-05/msg00115.html (9,255 bytes)
334. Re: [Amps] Real time tests to see if an RF transformer is saturating? (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Sun, 14 May 2017 16:55:49 +0000; Chris, it's very easy to calculate the flux density. Easier than measuring it. So, let's do the maths: You have 2kW applied to a 7 turn winding. Assuming the impedance at that point is 50 ohm, 2kW is; /archives//html/Amps/2017-05/msg00137.html (11,712 bytes)
335. Re: [Amps] Real time tests to see if an RF transformer is saturating? (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Sun, 14 May 2017 18:16:49 +0000; Alan, I can only say that great minds often think quite alike - and sometimes even at roughly the same time! ;-) Manfred == Visit my hobby homepage! http://ludens.cl == ______________________________; /archives//html/Amps/2017-05/msg00138.html (7,619 bytes)
336. Re: [Amps] Real time tests to see if an RF transformer is saturating? (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Tue, 16 May 2017 15:36:31 +0000; Chris, at that low frequency, indeed you can make the individual amps for 100 ohm and put them in parallel, or for 25 ohm and put them in series. There should be no phasing problems, at such a low fr; /archives//html/Amps/2017-05/msg00149.html (18,396 bytes)
337. Re: [Amps] Real time tests to see if an RF transformer is saturating? (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Tue, 16 May 2017 18:25:40 +0000; Chris, I stacked 3 off 78 material cores in the same size as the 77 material toroids and wound them with 180 strand speaker wire with a conductor diameter of about 2mm. This sounds like you misunders; /archives//html/Amps/2017-05/msg00154.html (9,786 bytes)
338. Re: [Amps] Stripping Litz (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Wed, 17 May 2017 17:11:29 +0000; Litz wire most commonly has polyurethane insulation. This is solderable - you don't need to strip it! Just set the soldering iron to a slightly hotter temperature than normal, then take the iron and; /archives//html/Amps/2017-05/msg00167.html (8,285 bytes)
339. Re: [Amps] Stripping Litz (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Sun, 21 May 2017 15:58:58 +0000; Chris, Even using the hot air tip on a butane soldering iron for a minute fails to do more than darken the insulation, as does a bare flame. It's a nightmare to strip,.... Well, MOST Litz wire is of; /archives//html/Amps/2017-05/msg00207.html (11,097 bytes)
340. Re: [Amps] new amp race (score: 1): Author: Manfred Mornhinweg <manfred@ludens.cl>; Date: Sun, 21 May 2017 17:03:16 +0000; My own motivation to use legal limit power is man-made noise on the other end. In the 1980's I worked lots of QRP. First just one watt in DSB, then I improved to 5W in DSB, then 5W in SSB, then 30W.; /archives//html/Amps/2017-05/msg00209.html (11,988 bytes)

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