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361. Re: [Amps] Any designs for 4CX1000A on 2m ? (score: 1): Author: "Dr. David Kirkby" <david.kirkby@onetel.net>; Date: Tue, 07 Jun 2011 01:19:24 +0100; Thanks Mark, that looks just what I was looking for. I doubt I'll have the "luxury" features, as I would like to build this ready for a contest in the 3rd September. It does not give me long to sourc; /archives//html/Amps/2011-06/msg00082.html (7,923 bytes)
362. Re: [Amps] Any designs for 4CX1000A on 2m ? (score: 1): Author: "Dr. David Kirkby" <david.kirkby@onetel.net>; Date: Tue, 07 Jun 2011 09:31:14 +0100; Thanks Bill. Mark, K5AM sent me this link. Is that the amp you mean? http://www.zianet.com/k5am/2mkw.pdf or was there another? Dave G8WRB. -- A: Because it messes up the order in which people normall; /archives//html/Amps/2011-06/msg00087.html (12,384 bytes)
363. Re: [Amps] Dummy load varying R (score: 1): Author: "Dr. David Kirkby" <david.kirkby@onetel.net>; Date: Mon, 13 Jun 2011 13:47:35 +0100; I think anything from MFJ is pretty poor. A friend describes it as "More **ing Junk". <snip> I'm fairly lucky in having a 5 kW Bird load on semi-permanent loan. But when I was active on 2m (long ago); /archives//html/Amps/2011-06/msg00163.html (11,744 bytes)
364. [Amps] Watch out for a scam by Alex Barski. VE3XAX (score: 1): Author: David Kirkby <david.kirkby@onetel.net>; Date: Wed, 15 Jun 2011 11:42:12 +0100; I advertised on eHam.net and qrz.com that I was looking for a Kenwood AT-230 ATU. I got a reply from someone claiming to be Alex Barski from Canada with the callsign VE3XAX who has an email address o; /archives//html/Amps/2011-06/msg00172.html (8,373 bytes)
365. Re: [Amps] Watch out for a scam by... (score: 1): Author: "Dr. David Kirkby" <david.kirkby@onetel.net>; Date: Thu, 16 Jun 2011 01:23:24 +0100; I can't be bothered to look it up, but I know there is one where someone got some real gold from a scammer. The scammer claimed to have gold of X % purity, but the baiter requested a sample so he cou; /archives//html/Amps/2011-06/msg00175.html (7,463 bytes)
366. Re: [Amps] Shipping to Japan (score: 1): Author: "Dr. David Kirkby" <david.kirkby@onetel.net>; Date: Mon, 20 Jun 2011 10:56:55 +0100; There are numerous options - USPS, UPS, Fedex, DHL .. etc. The problem with all these services is that if you only ship a small quantity of items, you pay a fairly large amount in shipping fees. What; /archives//html/Amps/2011-06/msg00261.html (8,199 bytes)
367. Re: [Amps] Shipping to Japan (score: 1): Author: "Dr. David Kirkby" <david.kirkby@onetel.net>; Date: Tue, 21 Jun 2011 12:46:30 +0100; I've found that items sent via Fedex attract duty more often than those shipped by USPS into the UK. I think customs know Fedex is used to transport higher value items, so there's more to be gained f; /archives//html/Amps/2011-06/msg00280.html (9,732 bytes)
368. [Amps] Using switch mode power supply for heater power (score: 1): Author: "Dr. David Kirkby" <david.kirkby@onetel.net>; Date: Tue, 28 Jun 2011 13:57:55 +0100; I'm looking at building a 4CX1000A amp, which I want to make as small/light as practical. Using an SMPS for the heater would go some way to this, whilst offering regulation, since my own supply varie; /archives//html/Amps/2011-06/msg00300.html (8,211 bytes)
369. Re: [Amps] Using switch mode power supply for heater power (score: 1): Author: "Dr. David Kirkby" <david.kirkby@onetel.net>; Date: Tue, 28 Jun 2011 23:03:15 +0100; Thank you. Though that needs another psu - I know one will probably be available, but it would be nice to make the heater supply self-contained. Very true, but there are two things to consider. 1) Th; /archives//html/Amps/2011-06/msg00310.html (12,155 bytes)
370. Re: [Amps] DIODE PIV Confusion (score: 1): Author: "Dr. David Kirkby" <david.kirkby@onetel.net>; Date: Wed, 29 Jun 2011 17:38:08 +0100; You can't measure the PIV - that is something that manufactures design for. You could measure the voltage at which it avalanches, but that would not be the PIV. Personally I would look at the circuit; /archives//html/Amps/2011-06/msg00318.html (7,949 bytes)
371. Re: [Amps] DIODE PIV Confusion (score: 1): Author: "Dr. David Kirkby" <david.kirkby@onetel.net>; Date: Wed, 29 Jun 2011 19:11:36 +0100; Sounds like a cheap source of 155 V "zener" diodes - or to be more precise "avalanche" diodes! (Only joking, I'd rather use a diode designed as a voltage regulator) G8WRB -- A: Because it messes up t; /archives//html/Amps/2011-06/msg00325.html (8,348 bytes)
372. Re: [Amps] DIODE PIV Confusion (score: 1): Author: "Dr. David Kirkby" <david.kirkby@onetel.net>; Date: Thu, 30 Jun 2011 09:25:52 +0100; True - very true. 155 V would be too low, but a pair of them in series gives 310 V, which is about right for a number of tubes! IIRC, both 4CX250B and 4CX1000A want 300 V on the screen, but I'm sure; /archives//html/Amps/2011-06/msg00336.html (9,762 bytes)
373. Re: [Amps] Filament Suppy, Info for G8WRB (score: 1): Author: "Dr. David Kirkby" <david.kirkby@onetel.net>; Date: Sun, 03 Jul 2011 04:51:05 +0100; Thank you. It's a bit hard to make use of, as I only know English. I see the link to eBay for 5 V SMPS, but any I've found can only be trimmed +/- 10%, so giving a maximum output voltage of 5.5 V, so; /archives//html/Amps/2011-07/msg00010.html (7,759 bytes)
374. [Amps] Risks from continuous discharge of high voltage ?? (score: 1): Author: "Dr. David Kirkby" <david.kirkby@onetel.net>; Date: Sun, 03 Jul 2011 13:27:27 +0100; 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/msg00012.html (7,428 bytes)
375. Re: [Amps] High SWR (score: 1): Author: "Dr. David Kirkby" <david.kirkby@onetel.net>; Date: Mon, 04 Jul 2011 22:20:11 +0100; You can't change the resonate frequency of an antenna by adjusting the amplifier. The frequency of resonance of an antenna is for all practical purposes independent of how the amp is tuned. You will; /archives//html/Amps/2011-07/msg00034.html (7,804 bytes)
376. [Amps] You must see this tube on eBay (score: 1): Author: "Dr. David Kirkby" <david.kirkby@onetel.net>; Date: Mon, 04 Jul 2011 22:35:29 +0100; It looks like someone has taken a hammer to this, but the seller wants $250. http://www.ebay.co.uk/itm/290577205205 -- A: Because it messes up the order in which people normally read text. Q: Why is; /archives//html/Amps/2011-07/msg00035.html (6,588 bytes)
377. [Amps] Close equivalents of the 4CX1500B (score: 1): Author: "Dr. David Kirkby" <david.kirkby@onetel.net>; Date: Mon, 04 Jul 2011 23:17:35 +0100; I've seen a few tubes on eBay which the seller claims are the 4CX1500B. This beaten up beast http://www.ebay.co.uk/itm/290577205205 is a Y763, which is claimed to be a 4CX1500B. This one is a YU-127; /archives//html/Amps/2011-07/msg00036.html (7,195 bytes)
378. Re: [Amps] High SWR (score: 1): Author: "Dr. David Kirkby" <david.kirkby@onetel.net>; Date: Tue, 05 Jul 2011 00:06:50 +0100; No, you can't make an antenna resonate. In general an antenna has a complex impedance R + j X. Only when X == 0 is there resonance. I would not consider you are resonating the antenna in this case. Y; /archives//html/Amps/2011-07/msg00038.html (11,985 bytes)
379. [Amps] Anyone got an HT transformer in the UK ? (score: 1): Author: "Dr. David Kirkby" <david.kirkby@onetel.net>; Date: Tue, 05 Jul 2011 00:20:17 +0100; I'm looking for a transformer of about 2500 V at about 1.2 A. Anyone got one in the UK? I'm looking to power a 4CX100A or 4CX1500B, both of which need about 3 kV at 1 A DC. Dave -- A: Because it mess; /archives//html/Amps/2011-07/msg00039.html (6,887 bytes)
380. Re: [Amps] High SWR (score: 1): Author: David Kirkby <david.kirkby@onetel.net>; Date: Tue, 5 Jul 2011 17:14:54 +0100; Well, that is new to me. I thought I had a decent understanding of what resonance was. I did a degree in electrical and electronic engineering, have a masters degree in microwaves and opto-electronic; /archives//html/Amps/2011-07/msg00053.html (10,311 bytes)

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