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Total 417 documents matching your query.

321. Re: [Amps] SB-220 HV Transformer Wanted ; thread stolen for (score: 1)
Author: Vic Rosenthal <k2vco.vic@gmail.com>
Date: Sat, 2 Nov 2019 07:21:52 +0200
We had one of those 1 kw Raytheon transmitters at WKOP in the early 60s and the 833A modulators were class B. But the push-pull RF final pair of 833As was class C. Victor 4X6GP (ex K2VCO) ___________
/archives//html/Amps/2019-11/msg00025.html (10,474 bytes)

322. Re: [Amps] SB-220 flash over in power supply (score: 1)
Author: Victor Rosenthal 4X6GP <k2vco.vic@gmail.com>
Date: Sat, 14 Dec 2019 06:35:02 +0200
_______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
/archives//html/Amps/2019-12/msg00021.html (6,655 bytes)

323. Re: [Amps] SB-220 flash over in power supply (score: 1)
Author: Victor Rosenthal 4X6GP <k2vco.vic@gmail.com>
Date: Sat, 14 Dec 2019 17:15:07 +0200
Sorry. Here it is: I've heard that RF can damage electrolytic caps, so it it a problem. You might try paralleling a larger bypass capacitor at the bottom of the choke. If you do that, you will notice
/archives//html/Amps/2019-12/msg00025.html (10,521 bytes)

324. Re: [Amps] Low efficiency on 160 m (score: 1)
Author: Victor Rosenthal 4X6GP <k2vco.vic@gmail.com>
Date: Mon, 16 Dec 2019 21:26:07 +0200
I am sure most know this, but if you use a scope to measure RF voltage, be sure to compare the voltage rating of your scope probes to the maximum voltage that you expect. Note that the rating goes do
/archives//html/Amps/2019-12/msg00034.html (10,330 bytes)

325. Re: [Amps] Laminated core toroids (score: 1)
Author: Victor Rosenthal <k2vco.vic@gmail.com>
Date: Mon, 20 Jan 2020 18:38:32 +0200
I don't think so. I think they are "tape wound cores", useful for low audio frequencies. 73, Victor, 4X6GP Rehovot, Israel Formerly K2VCO CWops no. 5 http://www.qsl.net/k2vco/ On 20/01/2020 17:30, Ji
/archives//html/Amps/2020-01/msg00028.html (7,426 bytes)

326. Re: [Amps] Transformer Question (score: 1)
Author: Victor Rosenthal 4X6GP <k2vco.vic@gmail.com>
Date: Thu, 27 Feb 2020 14:49:27 +0200
I suspect those capacitors were actually in series and he added up the values printed on them. 73, Victor, 4X6GP Rehovot, Israel Formerly K2VCO CWops no. 5 http://www.qsl.net/k2vco/ On 27/02/2020 14:
/archives//html/Amps/2020-02/msg00124.html (8,052 bytes)

327. Re: [Amps] Henry 2K-4 Failure (score: 1)
Author: Victor Rosenthal 4X6GP <k2vco.vic@gmail.com>
Date: Wed, 18 Mar 2020 18:11:14 +0200
_______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
/archives//html/Amps/2020-03/msg00074.html (6,822 bytes)

328. Re: [Amps] Ten Tec Titan Power Supply (score: 1)
Author: Vic Rosenthal <k2vco.vic@gmail.com>
Date: Wed, 25 Mar 2020 07:28:09 +0200
But if it turns out some are bad, replace ALL of them with 105c caps from a reputable distributor, like Digikey or Mouser, etc. Old electrolytics can be unreliable and a failure could damage the tran
/archives//html/Amps/2020-03/msg00105.html (9,679 bytes)

329. [Amps] Johnson KW Matchbox relay question (score: 1)
Author: Victor Rosenthal 4X6GP <k2vco.vic@gmail.com>
Date: Tue, 21 Apr 2020 17:56:07 +0300
Not exactly an amp question, but you guys will know. I have a relay that was removed from a Johnson KW matchbox. I know the Matchbox relay operated from 115 vac, but the relay is not an AC relay. I s
/archives//html/Amps/2020-04/msg00008.html (7,167 bytes)

330. Re: [Amps] Johnson KW Matchbox relay question (score: 1)
Author: Victor Rosenthal <k2vco.vic@gmail.com>
Date: Tue, 21 Apr 2020 19:29:49 +0300
Paul, Thanks. It's a DC relay then. I'll put together a little power supply for it. I want it to reconfigure my open-wire dipole as a T shaped vertical for 80m. I need a relay that can stand the very
/archives//html/Amps/2020-04/msg00011.html (9,225 bytes)

331. Re: [Amps] Matchbox and relay (score: 1)
Author: Victor Rosenthal 4X6GP <k2vco.vic@gmail.com>
Date: Wed, 22 Apr 2020 18:44:20 +0300
Yes, I remember the smell of burning selenium rectifier very well! I am going to use the relay to switch my open-line fed antenna to a "T" configuration for 80m. Incidentally, I love the Matchbox. Th
/archives//html/Amps/2020-04/msg00015.html (8,281 bytes)

332. Re: [Amps] 3cx800 13.5Vac 3amp filament transformer (score: 1)
Author: Victor Rosenthal 4X6GP <k2vco.vic@gmail.com>
Date: Sat, 2 May 2020 08:00:22 +0300
_______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
/archives//html/Amps/2020-05/msg00001.html (6,752 bytes)

333. Re: [Amps] SB220 Meter blown (score: 1)
Author: Victor Rosenthal 4X6GP <k2vco.vic@gmail.com>
Date: Sat, 16 May 2020 06:30:38 +0300
_______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
/archives//html/Amps/2020-05/msg00021.html (8,279 bytes)

334. Re: [Amps] New Eimac Tube (score: 1)
Author: Vic Rosenthal <k2vco.vic@gmail.com>
Date: Sun, 14 Jun 2020 08:00:41 +0300
Plunger type anode Urinated tungsten Victor 4X6GP _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
/archives//html/Amps/2020-06/msg00033.html (7,219 bytes)

335. Re: [Amps] Tl- 922 (score: 1)
Author: Victor Rosenthal 4X6GP <k2vco.vic@gmail.com>
Date: Wed, 15 Jul 2020 05:39:18 +0300
I'm guessing the problem is high plate current/negative grid current with no drive? That's a symptom of grid-filament short. Note that it's often the case that it shorts only when hot. Try taking out
/archives//html/Amps/2020-07/msg00003.html (8,090 bytes)

336. Re: [Amps] Push pull amps (score: 1)
Author: Victor Rosenthal 4X6GP <k2vco.vic@gmail.com>
Date: Sat, 1 Aug 2020 21:08:52 +0300
I think the main reason they liked putting triode amplifiers in push-pull was to simplify the neutralization. Of course it is possible to neutralize single-ended amps with a bridge circuit or to use
/archives//html/Amps/2020-08/msg00005.html (8,193 bytes)

337. Re: [Amps] Weakness of first two letters of call signs (score: 1)
Author: Victor Rosenthal 4X6GP <k2vco.vic@gmail.com>
Date: Tue, 6 Oct 2020 14:09:42 +0300
Jeff, I don't think most amps do this, but I know that some transceivers do (e.g., the Elecraft K3 under some circumstances, due to its closed-loop power control). There is also a psychological mecha
/archives//html/Amps/2020-10/msg00008.html (9,223 bytes)

338. Re: [Amps] Old SB1000 built by me in 1988 (score: 1)
Author: Victor Rosenthal 4X6GP <k2vco.vic@gmail.com>
Date: Sun, 13 Dec 2020 22:04:44 +0200
Look at the band switch. The sizzling might be an arc caused by corona discharge. That is a common SB1000 problem and will destroy the switch if it hasn't already. There could also be an arc in the l
/archives//html/Amps/2020-12/msg00018.html (9,651 bytes)

339. Re: [Amps] Looking for Alpha 87A expertise (score: 1)
Author: Victor Rosenthal <k2vco.vic@gmail.com>
Date: Mon, 15 Mar 2021 12:49:24 +0200
There is a high-speed version of the 1N4007, the UF4007 whose recovery time is specified as 75 ns. That's pretty fast! See <https://www.vishay.com/docs/88755/uf4001.pdf> The regular 1N4007 is more li
/archives//html/Amps/2021-03/msg00012.html (9,854 bytes)

340. Re: [Amps] Switching between two amplifiers (score: 1)
Author: Victor Rosenthal 4X6GP <k2vco.vic@gmail.com>
Date: Sat, 3 Apr 2021 18:22:23 +0300
_______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
/archives//html/Amps/2021-04/msg00003.html (6,788 bytes)

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