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301. Re: [Amps] GBR and radiation exposure (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Fri, 20 Aug 2004 13:16:16 +0200; 140kV It's much more likely that it was the result of years of UK management style - that's enough to drive anyone crazy. 73 Peter SM/G3RZP _______________________________________________ Amps mailin; /archives//html/Amps/2004-08/msg00224.html (7,542 bytes)
302. Re: [Amps] Pin Diodes? (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Fri, 20 Aug 2004 15:33:48 +0200; Worth looking at microsemi - their UM6201, 6901 and 7101 are pretty similar devices, and maybe cheaper. 73 Peter SM/G3RZP _______________________________________________ Amps mailing list Amps@conte; /archives//html/Amps/2004-08/msg00227.html (6,584 bytes)
303. Re: [Amps] Pin Diodes? (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Fri, 20 Aug 2004 17:51:59 +0200; I've actually used 1N4007s quite successfully - they have a long carrier life time, but do need a fair amount of current through them. The reverse capacity could be aproblem if there isn't a fair amo; /archives//html/Amps/2004-08/msg00233.html (7,332 bytes)
304. Re: [Amps] SAFETY WITH HIGH VOLTAGE (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Mon, 23 Aug 2004 07:58:29 +0100; I'd agree that the 53 ohm one sounds suspiciously low: I suppose it's possible it arced from turn to turn and fused that way. can you see anything wrong with it on a visual inspection? The usual reas; /archives//html/Amps/2004-08/msg00265.html (7,912 bytes)
305. Re: [Amps] 4-250A (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Wed, 25 Aug 2004 10:20:29 +0100; 4-250A. Spares for British Army D13 transmitter also Marconi NT201 naval tx. Nice tubes, I use a pair of them, theyglow a nice red at full dissipation, go nicely with 3600 or so on the anode. Design; /archives//html/Amps/2004-08/msg00287.html (7,218 bytes)
306. Re: [Amps] Transceivers (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Mon, 6 Sep 2004 08:33:01 +0200; and off the mixer tube it does become a very effective >frequency mixer. It then appears to be an analog mixer multiplying a signal with a square wave. It does reduce the conversion gain, though. Tha; /archives//html/Amps/2004-09/msg00098.html (7,707 bytes)
307. Re: [Amps] re cooling of coils (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Mon, 6 Sep 2004 08:36:26 +0200; Giving credit where 'tis due, it was a comment here of Rich's which led me to do a few simple sums on the losses in the tank coils. that convinced me that a small fan blöowing air over/through/a; /archives//html/Amps/2004-09/msg00099.html (7,886 bytes)
308. Re: [Amps] Transceivers (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Mon, 6 Sep 2004 11:42:19 +0200; Will, Applying signal and oscillator to g1 is, as you say, an old technique. It had problems when the oscillator is a long way from the signal frequency, in that the input tuned circuit attenuates th; /archives//html/Amps/2004-09/msg00109.html (7,772 bytes)
309. Re: [Amps] Panasonic tube radio (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Sun, 12 Sep 2004 10:26:48 +0200; I find the older ones (1946 to about 1965)even more interesting. As a percentage, did many more people build their rigs rather than buy? Kits were perhaps more available, which skews the numbers a bi; /archives//html/Amps/2004-09/msg00214.html (7,433 bytes)
310. Re: [Amps] Equalising resistors with HV diodes (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Mon, 20 Sep 2004 13:22:41 +0100; To a point. IF the diodes all come from the same diffusion batch, it's probable, although if the wafer is large, you can see generally see differences from one side of the wafer to the other. Don't l; /archives//html/Amps/2004-09/msg00349.html (8,521 bytes)
311. Re: [Amps] Equalising resistors with HV diodes (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Mon, 20 Sep 2004 14:08:51 +0100; Because if the reverse leakage differs between diodes, the reverse voltage distribution also differs. The one with the least leakage ends up with the highest voltage across it, which could exceed the; /archives//html/Amps/2004-09/msg00351.html (8,527 bytes)
312. Re: [Amps] Equalising resistors with HV diodes (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Mon, 20 Sep 2004 15:24:12 +0100; I don't follow that argument. In a bridge, the 'off' diodes are effectively in parallel, not series. Substitute bits of wire for the 'ON' diode and analyse for one half cycle. I may be considered a b; /archives//html/Amps/2004-09/msg00354.html (9,039 bytes)
313. Re: [Amps] Equalising resistors with HV diodes (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Tue, 21 Sep 2004 08:30:01 +0100; Rich's argument appears to me that because the current is the same in each diode, and each diode goes into avalanche, the voltage distribution on any one diode can't be such as to exceed the the reve; /archives//html/Amps/2004-09/msg00371.html (11,341 bytes)
314. Re: [Amps] Equalising resistors with HV diodes (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Tue, 21 Sep 2004 09:11:07 +0100; Traian makes a very good point. Some 35 years ago now, I was at a company doing MF SSB maritime transceivers. The Buyer was instructed to buy the cheapest transistors, and bought from Microelectronic; /archives//html/Amps/2004-09/msg00373.html (9,699 bytes)
315. Re: [Amps] Equalising resistors with HV diodes (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Wed, 22 Sep 2004 07:49:51 +0100; Why? Die area is related to the current: voltage to the diffusion profile. So is the gamma, the factorr elating reverse volatge and capacitance. I didn't intend to come to work today, as I'm about to; /archives//html/Amps/2004-09/msg00393.html (9,975 bytes)
316. Re: [Amps] Re: Equalizing resistors with HV diodes (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Wed, 22 Sep 2004 09:03:26 +0100; There is a limit to how thick you can deposit metal. The Unitrode process, which uses the end of the lead in direct contact has some advantages here. At least in diodes, you don't tend to get the ste; /archives//html/Amps/2004-09/msg00395.html (11,843 bytes)
317. Re: [Amps] Linearity metering (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Fri, 8 Oct 2004 11:50:42 +0100; Used one of these circuits for years on my amp. Works pretty well: beiggest problem is making sure the rectifiers (or rather the coupling/attenuation feeding them) gives a either a flat output over t; /archives//html/Amps/2004-10/msg00090.html (7,311 bytes)
318. Re: [Amps] Plate modulator xmfr ? (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Mon, 11 Oct 2004 10:40:50 +0200; One point to bear in mind is that the secondary of the modulation transformer has a lot of DC in it, which means that you need more iron (and probably an air gap) to avoid the core being saturated by; /archives//html/Amps/2004-10/msg00140.html (8,510 bytes)
319. Re: [Amps] Plate modulator xmfr ? (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Mon, 11 Oct 2004 13:08:50 +0200; I believe AM B/C xmtrs (if they're still being made with tubes!) tend to go for pulse width modulated type amplifiers for the modulation, and no transformers. Over here, the aithorities even intend t; /archives//html/Amps/2004-10/msg00142.html (8,021 bytes)
320. Re: [Amps] Mod xmfr (score: 1): Author: peter.chadwick@Zarlink.Com; Date: Mon, 11 Oct 2004 16:36:17 +0200; Just don't forget the air gap so that the secondary doesn't produce enough field to saturate the core. That will also mean that for any given primary impedance, you'll effectively need more turns th; /archives//html/Amps/2004-10/msg00147.html (6,530 bytes)

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