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Total 419 documents matching your query.

241. Re: [Amps] HV transformer and Variac (score: 1)
Author: Manfred Mornhinweg <manfred@ludens.cl>
Date: Wed, 22 Jul 2015 17:57:49 +0000
Some general concepts about using transformers at lower voltage than rated: The magnetic flux density in the core will be proportionally lower, and for this reason the power loss in the core will be
/archives//html/Amps/2015-07/msg00097.html (11,381 bytes)

242. Re: [Amps] HV transformer and Variac (score: 1)
Author: Manfred Mornhinweg <manfred@ludens.cl>
Date: Thu, 23 Jul 2015 14:09:11 +0000
Buy a 3KVA transformer from Heybour for $500.00 and be done with it. Small, compact, and it will work better. Yes. Or buy the materials and wind it yourself. It will be some work, but the cost will b
/archives//html/Amps/2015-07/msg00103.html (9,116 bytes)

243. Re: [Amps] HV transformer and Variac (score: 1)
Author: Manfred Mornhinweg <manfred@ludens.cl>
Date: Fri, 24 Jul 2015 18:22:15 +0000
Just a little more trivia on the comparison between transformers and autotransformers: Let's consider an autotransformer with the tap at the center. Assume we are applying 240V input, and get 120V ou
/archives//html/Amps/2015-07/msg00117.html (11,899 bytes)

244. Re: [Amps] HV transformer and Variac (score: 1)
Author: Manfred Mornhinweg <manfred@ludens.cl>
Date: Sun, 26 Jul 2015 21:17:22 +0000
About the carbon tap of a VARIAC: I also have wondered about the loss caused by the nearly shorted turn or turns. And I have a slightly more elaborate theory about what happens there: It happens that
/archives//html/Amps/2015-07/msg00147.html (10,260 bytes)

245. Re: [Amps] Transmit signal monitoring AM & SSB (score: 1)
Author: Manfred Mornhinweg <manfred@ludens.cl>
Date: Wed, 29 Jul 2015 23:51:28 +0000
Joe, I plan on trying some AM. I remember the old dedicated station monitors of the past. I've seen some RF samplers & AF demodulators. These seem to be in the $200 + range, along with the used older
/archives//html/Amps/2015-07/msg00182.html (11,655 bytes)

246. [Amps] IMD and spurious measurements (score: 1)
Author: Manfred Mornhinweg <manfred@ludens.cl>
Date: Sat, 08 Aug 2015 17:07:45 +0000
Hi all, I have been playing yesterday and today, measuring the signal purity of my station under many different conditions. The test equipment used is the one I described a few days ago: A DDS signal
/archives//html/Amps/2015-08/msg00007.html (15,172 bytes)

247. Re: [Amps] IMD and spurious measurements (score: 1)
Author: Manfred Mornhinweg <manfred@ludens.cl>
Date: Sun, 09 Aug 2015 14:24:29 +0000
Hi all, thanks for all the replies about my funny signals! I will make more tests, and reply in detail once I think I know what's really happening. Manfred == Visit my hobby homepage! http://ludens.c
/archives//html/Amps/2015-08/msg00017.html (7,401 bytes)

248. Re: [Amps] IMD and spurious measurements (score: 1)
Author: Manfred Mornhinweg <manfred@ludens.cl>
Date: Tue, 11 Aug 2015 15:49:50 +0000
Hi Gary, Karl-Arne, Steve, Bill, Ron, Peter, etc, As promised, here is the follow-up of my strange spurs measurements. Indeed it would be quite strange to see DX broadcast signals, that come in at ab
/archives//html/Amps/2015-08/msg00018.html (13,742 bytes)

249. [Amps] Blower noise (score: 1)
Author: Manfred Mornhinweg <manfred@ludens.cl>
Date: Tue, 11 Aug 2015 16:13:21 +0000
Does anyone have a good idea for reducing blower noise? I end up rarely using my NCL-2000 amplifier, because the blower noise is so disturbing! I measured it now. The intensity is 52dBA, measured at
/archives//html/Amps/2015-08/msg00020.html (11,163 bytes)

250. Re: [Amps] Blower noise (score: 1)
Author: Manfred Mornhinweg <manfred@ludens.cl>
Date: Thu, 13 Aug 2015 15:13:12 +0000
Steven, Jim, Drax, Mike, Alek, Russ, Chris, Roger, However, 12Vdc brushless motors usually have an inverter inside them, so they're really AC motors (higher frequency) operated from a DC source; as s
/archives//html/Amps/2015-08/msg00040.html (20,135 bytes)

251. Re: [Amps] Blower noise (score: 1)
Author: Manfred Mornhinweg <manfred@ludens.cl>
Date: Fri, 14 Aug 2015 19:21:42 +0000
Mike, Slowing a blower can significantly reduce the back pressure. Be careful that you have enough pressure to get the required airflow for the rated anode dissipation. I'm very well aware of that. I
/archives//html/Amps/2015-08/msg00046.html (10,765 bytes)

252. Re: [Amps] Regulated filament current (score: 1)
Author: Manfred Mornhinweg <manfred@ludens.cl>
Date: Fri, 04 Sep 2015 17:06:46 +0000
Bob, I'm 100% with Jim here. If the tube manufacturer tells you "use 12.6V, plus/minus 5%", then do that! It means that the manufacturer tested his tubes with higher and lower voltage, trimmed the fi
/archives//html/Amps/2015-09/msg00011.html (9,693 bytes)

253. Re: [Amps] BLF188xr amp (score: 1)
Author: Manfred Mornhinweg <manfred@ludens.cl>
Date: Thu, 15 Oct 2015 17:00:08 +0000
Hi Chris, They brag about 65:1 swr survivability, but this is pulsed. It's thermally limited. Basically this rating means that the FET can avalanche safely if a high SWR results in high voltage pulse
/archives//html/Amps/2015-10/msg00046.html (9,617 bytes)

254. Re: [Amps] Amps Digest, Vol 154, Issue 9 (score: 1)
Author: Manfred Mornhinweg <manfred@ludens.cl>
Date: Sat, 17 Oct 2015 18:25:41 +0000
Bill, It isn't SWR that kills a transistor, it's the EFFECT of SWR - excess voltage or current at the drain. Or excess dissipated power. Some load impedances result in acceptable voltages and current
/archives//html/Amps/2015-10/msg00048.html (8,152 bytes)

255. Re: [Amps] question about SPE 1.3K FA amp (score: 1)
Author: Manfred Mornhinweg <manfred@ludens.cl>
Date: Tue, 10 Nov 2015 18:41:43 +0000
Probably something similar to the NXP BLF188XR According to what's stated on some websites, they used an MRFE6VP61K25H. From the IMD data given in previous posts, I suspect that the amplifier is desi
/archives//html/Amps/2015-11/msg00051.html (11,113 bytes)

256. Re: [Amps] Question about SPE 1.3K-FA amplifier (score: 1)
Author: Manfred Mornhinweg <manfred@ludens.cl>
Date: Thu, 12 Nov 2015 14:02:16 +0000
Here is a link to what looks like the Test Report for FCC Type Acceptance. https://fccid.io/pdf.php?id=2443307 Curious as to what folks think about the results. It seems to be a test report made _by_
/archives//html/Amps/2015-11/msg00067.html (14,189 bytes)

257. Re: [Amps] SPE 1.3K-FA and FTDX-5KMP / IMD at rated PEP (score: 1)
Author: Manfred Mornhinweg <manfred@ludens.cl>
Date: Mon, 16 Nov 2015 21:18:09 +0000
I agree on the fact that there is currently too much hype about signal purity on the side of some hams, while other hams coulnd't care less about signal purity, and just want to get out as loud as po
/archives//html/Amps/2015-11/msg00107.html (17,953 bytes)

258. Re: [Amps] SPE 1.3K-FA and FTDX-5KMP / IMD at rated PEP (score: 1)
Author: Manfred Mornhinweg <manfred@ludens.cl>
Date: Wed, 18 Nov 2015 15:15:16 +0000
Joe, and all, Even linearity correction will not work if the devices are being driven into saturation - the TV transmitter designers know that very well. Linearity correction works as long as there i
/archives//html/Amps/2015-11/msg00117.html (15,467 bytes)

259. Re: [Amps] SPE 1.3K-FA and FTDX-5KMP (score: 1)
Author: Manfred Mornhinweg <manfred@ludens.cl>
Date: Wed, 18 Nov 2015 19:24:11 +0000
Jim, and all, SPE is delusional if they think they are building state of the art amps. While I tend to smile about a manufacturer that brags about having 35,000 lines of code in the controller of his
/archives//html/Amps/2015-11/msg00121.html (13,456 bytes)

260. Re: [Amps] SPE 1.3K-FA and FTDX-5KMP (score: 1)
Author: Manfred Mornhinweg <manfred@ludens.cl>
Date: Sun, 22 Nov 2015 00:07:04 +0000
Cool, Compact, Quiet: choose any TWO. 73 from Ian GM3SEK REPLY: Cool, compact, headphones. 73, Bill W6WRT And my choice would be: High efficiency amplifier. Cool, compact, AND quiet. Plus a lower pow
/archives//html/Amps/2015-11/msg00144.html (9,384 bytes)

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