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References: [ +from:g3rzp@g3rzp.wanadoo.co.uk: 523 ]

Total 523 documents matching your query.

361. Re: [Amps] power supply transformer (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Wed, 31 Jan 2007 18:59:58 +0100 (CET)
schematics for their old transmitters. Others did it, too.< Doesn't mean it was good practice, or safe, though. 73 Peter W7/G3RZP (this week) _______________________________________________ Amps mail
/archives//html/Amps/2007-01/msg00345.html (8,650 bytes)

362. Re: [Amps] power supply transformer (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 4 Feb 2007 12:16:45 +0100 (CET)
Paul, If you run the amp directly off the rectified 117 (or whatever) line voltage, tehre's an insulation requirement between the drains of teeh MOSFETS and the RF output winding, which is grounded.
/archives//html/Amps/2007-02/msg00028.html (8,068 bytes)

363. Re: [Amps] power supply transformer (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 4 Feb 2007 17:38:53 +0100 (CET)
or to the safety ground anyplace except at the mains panel.< That's the case in the UK, too. The problem comes when you connect your external RF ground to the mains ground - in the event of a rupture
/archives//html/Amps/2007-02/msg00039.html (8,512 bytes)

364. Re: [Amps] 220 LINES (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 4 Feb 2007 17:45:45 +0100 (CET)
This is true, but it is hopefully, but not necessarily, at ground potential, depending on where it is grounded. I measured 24 volts with a 500mA availability between neutral and ground at the last pl
/archives//html/Amps/2007-02/msg00040.html (6,901 bytes)

365. Re: [Amps] 220 LINES (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 4 Feb 2007 18:55:24 +0100 (CET)
neutral and ground is done by the power company OUTSIDE the customer premises. < The bond may be done at or in the customer premises, although for domestic installations, usually isn't. In my case, t
/archives//html/Amps/2007-02/msg00043.html (7,465 bytes)

366. Re: [Amps] 3-500z - intermittent filament (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Tue, 6 Feb 2007 18:17:59 +0100 (CET)
The Mullard data sheet for the 4-250 and 4-400 equivalents (which have the same 5 volt, 14 amp filament as the 3-500Z) specifically call for a certain amount of cooling air over the socket pins. If y
/archives//html/Amps/2007-02/msg00084.html (7,843 bytes)

367. Re: [Amps] 3CV1500A7 (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Tue, 6 Feb 2007 18:23:25 +0100 (CET)
increases H2O temperature and thus the thermal process can quickly go out of control.< The book 'Radio Transmitters' by Brown, published by Peter Peregrinus in the early 70s (if you can find a copy a
/archives//html/Amps/2007-02/msg00085.html (7,763 bytes)

368. Re: [Amps] General question on filament life (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Fri, 9 Feb 2007 10:06:14 +0100 (CET)
off too many electrons to raise their hand, you wouldn't count many hands in the whole country. < Very true. I'm still using a 6L6G that my father bought in 1936 or 7. 73 Peter G3RZP ________________
/archives//html/Amps/2007-02/msg00154.html (8,681 bytes)

369. Re: [Amps] 3-500z - intermittent filament (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Fri, 9 Feb 2007 15:19:39 +0100 (CET)
There are some higher temperature 'soft solders' around, which don't require the red heat of hard solder. From memory, something called 'comsomal' or similar is about a 300 degree C or so solder. Per
/archives//html/Amps/2007-02/msg00158.html (8,741 bytes)

370. Re: [Amps] Thoriated tungsten lifetime when idling tspa (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 11 Feb 2007 13:26:41 +0100 (CET)
says limiting current to two times the operating value helps reduce damage (movement) from repeated filament thermal cycles.< But we all know that filament movement is caused by VHF parasitics, don't
/archives//html/Amps/2007-02/msg00176.html (7,642 bytes)

371. Re: [Amps] Thoriated tungsten lifetime when idling tspa (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 11 Feb 2007 13:34:14 +0100 (CET)
There can definitely be a problem running oxide coated cathodes for a long time without drawing current: it leads to a build up of cathode interface resistance, and according to one of my textbooks (
/archives//html/Amps/2007-02/msg00177.html (7,278 bytes)

372. Re: [Amps] 1 tube or two ?? (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 11 Feb 2007 22:58:01 +0100 (CET)
In big professional tx's for HF, they seemed generally (there were exceptions) to go for something around a 3 times power increase between models - 1kW, 3kW, 10kW, 30kW etc. Even these steps seem a b
/archives//html/Amps/2007-02/msg00194.html (8,610 bytes)

373. Re: [Amps] Lamps and surge protection (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Tue, 13 Feb 2007 10:19:49 +0100 (CET)
Interestingly, the old General Electric Company in the UK were always looking to save money. To this end, a study was carried out by their research group which showed that the reduction in life by sw
/archives//html/Amps/2007-02/msg00238.html (7,172 bytes)

374. Re: [Amps] Tubes (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Fri, 16 Feb 2007 09:31:05 +0100 (CET)
I remember reading that back in the early '80s, an IEEE Microwaves group visited Russia. According to the report, the Russians were amazed that they hadn't got 90GHz gyrotrons in the US, and actually
/archives//html/Amps/2007-02/msg00258.html (6,862 bytes)

375. Re: [Amps] Switching PS for filaments? (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 18 Feb 2007 10:59:04 +0100 (CET)
One problem that can arise is if the psu doesn't like providing the excess amps when you first switch because the filament is cold. I got a 5v 15A one for my 4CX1000 (yet to be built) amp: it won't s
/archives//html/Amps/2007-02/msg00267.html (7,763 bytes)

376. Re: [Amps] ML!-2500 Filter Cap Replacement (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Mon, 19 Feb 2007 14:05:11 +0100 (CET)
critical voltage equalizing or voltage dropping applications, because carbon resistors age down in value with heat and time< I've never found one that aged down in value, always the ones I've checked
/archives//html/Amps/2007-02/msg00292.html (9,836 bytes)

377. Re: [Amps] Power Transistor Question -- 2SC5125 (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Mon, 19 Feb 2007 18:02:32 +0100 (CET)
absolute maximum momentary temperature, 200 degrees Celsius. Running the transistor that hot will allow it to last only for a very short time, maybe just hours! You should run it at no more than 150
/archives//html/Amps/2007-02/msg00298.html (8,175 bytes)

378. Re: [Amps] *** SPAM *** Re: ML!-2500 Filter Cap Replacement (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Mon, 19 Feb 2007 18:09:49 +0100 (CET)
I don't know if you had them in the US, but over here, we had what were called 'high stability' carbon composition. These were distinguished by a pink band after the tolerance band, and were always i
/archives//html/Amps/2007-02/msg00299.html (7,128 bytes)

379. Re: [Amps] Dayton (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Wed, 21 Feb 2007 10:44:03 +0100 (CET)
Bob asked: I'll be there. Arriving Thursday pm from Dallas, expect to be at the usual SMC bash at Hooters in Lewisburg Thursday night, and in the SMC suite most evenings. 73 Peter G3RZP _____________
/archives//html/Amps/2007-02/msg00337.html (7,463 bytes)

380. Re: [Amps] Getting rid of blower noise - an alternate coolingscheme using the phase transition of liquid carbon dioxide (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Wed, 21 Feb 2007 16:37:10 +0100 (CET)
If you order your liquid CO2 cylinder with a dip tube, you gte liquid CO2 without having to have the cylinder upside down. As said, you need to watch the CO2 concentration. We used dip tube CO2 cylin
/archives//html/Amps/2007-02/msg00343.html (7,249 bytes)

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