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341. [Amps] PA efficiency (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Thu, 19 May 2011 07:32:03 -0700
You might have a hard time to reach even 60% efficiency from a VHF/UHF amp 73 Peter though. One should be able to by careful measurement, be able to calculate eff within a few percent.... not within
/archives//html/Amps/2011-05/msg00163.html (9,008 bytes)

342. [Amps] Should a blower run after amp shutdown? (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Fri, 3 Jun 2011 03:44:12 -0700
Like many homebrewers, I've always built a timer into my amps that powers the blower for a couple of minutes after killing power to the amplifier. Today, however, in a conversation with another build
/archives//html/Amps/2011-06/msg00014.html (11,144 bytes)

343. [Amps] Should a blower run after amp shutdown? (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Fri, 3 Jun 2011 08:00:28 -0700
Another caution, this time about constant voltage transformers. I had one of these and tried to use it to stabilize the mains to a signal generator to improve drift. It sort of worked but the main pr
/archives//html/Amps/2011-06/msg00024.html (11,834 bytes)

344. Re: [Amps] Should a blower run after amp shutdown? (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Fri, 3 Jun 2011 08:05:04 -0700
100% convinced that ramping down the fil V is less stressful on big fil's. It would certainly reduce thermal stress and shock. Emtron does the ramp up sequence...dunno if they do the ramp down part o
/archives//html/Amps/2011-06/msg00025.html (11,334 bytes)

345. [Amps] Dummy load varying R (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Wed, 8 Jun 2011 23:05:33 -0700
Maybe not quite amps related, but this is the best forum I know of for RF expertise ... Without belaboring irrelevant details, I'm calibrating an LP-100A wattmeter I just built. With a brand new MFJ
/archives//html/Amps/2011-06/msg00108.html (9,802 bytes)

346. [Amps] Voltage Doubler Regulation (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Tue, 14 Jun 2011 06:21:54 -0700
Many more variables need to be taken into account. Voltage regulation in a doubler circuit will always be poorer than in a similar full-wave bridge, and the series resistance of the transformer windi
/archives//html/Amps/2011-06/msg00169.html (9,605 bytes)

347. [Amps] Shipping to Japan (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Tue, 21 Jun 2011 01:49:06 -0700
Hi Gary, Although it's of little / no concern to the person initiating the shipment, the receiver of anything sent to Canada by way of a commercial carrier is liable for for the brokerage fees that s
/archives//html/Amps/2011-06/msg00275.html (10,139 bytes)

348. [Amps] Centurion (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Tue, 21 Jun 2011 02:25:27 -0700
I have a 10 year old Centurion, one of the pre-black front panel units. I have had almost the exact same experience with the h.v. supply transformer. After two failures I got the Dahl replacement (wh
/archives//html/Amps/2011-06/msg00277.html (11,296 bytes)

349. Re: [Amps] Shipping to Japan (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Tue, 21 Jun 2011 04:53:46 -0700
regardless of the size / weight of the box.... or it's value. They also charge BOTH fed and prov sales tax. [ hst these days]. Other than sales tax on the usa dollar exchange and the $5.00 per box fe
/archives//html/Amps/2011-06/msg00281.html (11,203 bytes)

350. [Amps] DIODE PIV Confusion (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Thu, 30 Jun 2011 02:25:16 -0700
I remember reading (on amps?) awhile back that there is in fact two different 6A10 diodes. On in 100 volts and the other is 1000 volts. I seem to remember that the 100 volt one was in Europe ? 73 Gar
/archives//html/Amps/2011-06/msg00337.html (8,149 bytes)

351. [Amps] Risks from continuous discharge of high voltage ?? (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Sun, 3 Jul 2011 18:09:27 -0700
There's an ebay auction for a 100 kV transformer from an x-ray set. http://www.ebay.co.uk/itm/190544288962 I mentioned to the seller he should warn people of possible production of x-rays. He does no
/archives//html/Amps/2011-07/msg00024.html (9,894 bytes)

352. [Amps] GS35b FWB issue (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Tue, 12 Jul 2011 03:49:19 -0700
I lost a diode string on an 8x4 string 1N5408 FWB on my single GS35b 6m HB amp. To whit, 8 x 1N5408s per leg of a FWB for a total of 32 diodes. aprx 3062 x 1.414 = 4330 vdc. If you want to do this ri
/archives//html/Amps/2011-07/msg00124.html (18,429 bytes)

353. [Amps] GS35b FWB issue (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Wed, 13 Jul 2011 01:31:54 -0700
I lost a diode string on an 8x4 string 1N5408 FWB on my single GS35b 6m HB amp. To whit, 8 5408s per leg of a FWB for a total of 32 diodes. Presumably a lightening strike / blown lightening arrestor,
/archives//html/Amps/2011-07/msg00128.html (9,097 bytes)

354. [Amps] Who sells 3CPX-800A7's besides RF parts ?? (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Wed, 13 Jul 2011 03:01:10 -0700
I use to know this..but lost the info. There was a couple of co's somewhere in the eastern usa that had... 'good' prices on 3CPX-800A7's. Tnx... Jim VE7RF ____________________________________________
/archives//html/Amps/2011-07/msg00129.html (6,472 bytes)

355. [Amps] Who sells 3CPX-800A7's besides RF parts ?? (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Wed, 13 Jul 2011 08:01:16 -0700
Do you need the pulsed version (P in the part number)? The 3CX800A7 is far more common than the 3CPX800A7. Without looking at the data sheets, I've no idea how similar they are. There are tons of 3CX
/archives//html/Amps/2011-07/msg00137.html (9,882 bytes)

356. [Amps] Plate Cap Quandary (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Wed, 3 Aug 2011 14:38:47 -0700
I'm contemplating a single 4CX350FJ (Cout = 7pF) amplifier for 250 watts on HF where the plate impedance, at 2200 volts, figures to be 5000 ohms and requires a (total) plate C circa 15pF on 10 meters
/archives//html/Amps/2011-08/msg00002.html (7,962 bytes)

357. [Amps] Plate Cap Quandary (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Sun, 7 Aug 2011 04:54:52 -0700
Date: Sat, 06 Aug 2011 11:39:58 -0700 From: Jim Barber <audioguy@q.com> Subject: Re: [Amps] Plate Cap Quandary To: Manfred Mornhinweg <manfred@ludens.cl> Cc: amps@contesting.com Message-ID: <4E3D8A7E
/archives//html/Amps/2011-08/msg00018.html (11,906 bytes)

358. [Amps] Any new tube research? (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Sat, 20 Aug 2011 09:34:14 -0700
I really don't see wide adoption of SS legal limit amps until the devices can be made more rugged, can be cooled more easily, and become available at much lower prices. Prices are based on tooling se
/archives//html/Amps/2011-08/msg00104.html (10,181 bytes)

359. [Amps] RF in the Audio (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Sat, 24 Sep 2011 23:29:32 -0700
I HAVE inserted the bifilar chokes between the output of a Titan 425 and the antenna tuner and tested at 1.5kW keydown for several minutes from 1.8 MHz to 28MHz. At that point, the choke sees ONLY th
/archives//html/Amps/2011-09/msg00186.html (12,673 bytes)

360. [Amps] RF in the Audio (score: 1)
Author: "Jim Thomson" <jim.thom@telus.net>
Date: Sat, 24 Sep 2011 23:48:20 -0700
Roger, you better keep your head down. I'm not sure who it will be (the G5RV crowd or the "open wire is perfect" crowd), but the chances of you meeting a bad ending from this statement is high! You a
/archives//html/Amps/2011-09/msg00187.html (8,500 bytes)

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