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Total 523 documents matching your query.

241. Re: [Amps] MTBF - was Ameritron Amps (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Mon, 31 Jul 2006 16:55:44 +0200 (CEST)
average. On the average, the unit in question will fail at that point, some less, some more and the variation of when the item will fail is dependant upon the sigma of the distribution< No disagreeme
/archives//html/Amps/2006-07/msg01435.html (7,816 bytes)

242. Re: [Amps] Ameritron Amps (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Mon, 31 Jul 2006 17:09:39 +0200 (CEST)
boron as a fluxing agent instead of lead.< Going back a few years, I remember reading that the 24G, 35T and 35TG had envelopes of something called 'Nonex' glass, which had a greenish tinge. Those tub
/archives//html/Amps/2006-07/msg01436.html (8,770 bytes)

243. Re: [Amps] Low Pass Filter capacitor ratings for 1.5kw level (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Tue, 1 Aug 2006 21:41:05 +0200 (CEST)
rating. A secondary worry is impedance of leads if you intend to reject very high frequency harmonics. The caps must of course have to have enough voltage, and the voltage can be higher than the inpu
/archives//html/Amps/2006-08/msg00011.html (7,995 bytes)

244. [Amps] Amplifier frustrations (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Tue, 1 Aug 2006 22:26:41 +0200 (CEST)
A tale that may amuse, and may even evoke sympathy........ Last year, I changed antennas. The 205BA at 62 feet and interlaced 4 ele beams for 10 and 15 at 68 feet went, replaced by a 4 ele Steppir at
/archives//html/Amps/2006-08/msg00013.html (11,112 bytes)

245. Re: [Amps] Amplifier frustrations (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Wed, 2 Aug 2006 11:43:48 +0200 (CEST)
This particular device uses a variable L in the pi network. that unrolls a silver plated phosphor bronze tape from a an insulating drum to big brass drum, and the plate tuning caps are ceramic tubs,
/archives//html/Amps/2006-08/msg00037.html (9,669 bytes)

246. Re: [Amps] AL811, AL811H or AL572 mods to 6m (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Wed, 2 Aug 2006 21:39:04 +0200 (CEST)
in the HF amplifiers chapter.< That deals nicely with the output side. But 811s and 572s have very long grid leads, which make them awful bloody things at 30, let alone 50MHz. So personally, I wouldn
/archives//html/Amps/2006-08/msg00053.html (8,731 bytes)

247. Re: [Amps] AL811, AL811H or AL572 mods to 6m (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Thu, 3 Aug 2006 09:04:26 +0200 (CEST)
How efficient, and what IMD? 73 Peter G3RZP _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
/archives//html/Amps/2006-08/msg00070.html (8,549 bytes)

248. Re: [Amps] Grid Vs cathode drive (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Thu, 3 Aug 2006 09:24:07 +0200 (CEST)
Hsu asked: My answer ( and it's doubtless open to argument) is two fold. First, the majority of transceivers are of the 100 to 200 watt output level, so a grounded grid triode is a convenient way to
/archives//html/Amps/2006-08/msg00071.html (8,379 bytes)

249. Re: [Amps] grid resonance (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Thu, 3 Aug 2006 09:27:34 +0200 (CEST)
to find a series resonance. My understanding is that's not correct.< If you short the component out, doesn't it become a parallel resonance? So if the Q is too low, the frequency will be different. 7
/archives//html/Amps/2006-08/msg00072.html (7,993 bytes)

250. Re: [Amps] grid resonance (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Thu, 3 Aug 2006 09:34:53 +0200 (CEST)
tell where the antenna connected at the other end is high impedance or low impedance! Why would anyone do that?< I don't see what a GDO would tell you, but an impedance bridge would - although you wo
/archives//html/Amps/2006-08/msg00073.html (8,730 bytes)

251. Re: [Amps] G2DAF four 4CX250Bs G2DAF amplifier (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Thu, 3 Aug 2006 09:50:05 +0200 (CEST)
DON'T DON'T DON'T!!!!! The G2DAF is not very good for linearity, despite the claims. Neither is the 4CX250B, without negative feedback, and a well regulated screen grid supply, capable of absorbing n
/archives//html/Amps/2006-08/msg00075.html (7,281 bytes)

252. Re: [Amps] G2DAF four 4CX250Bs G2DAF amplifier (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Thu, 3 Aug 2006 15:36:17 +0200 (CEST)
Both. There's been a lot of argument about the basic G2DAF ciruitry over the years. Right back when it was published (and I'm probably the only person on this reflector to have read the original arti
/archives//html/Amps/2006-08/msg00087.html (9,174 bytes)

253. Re: [Amps] Grid Vs cathode drive (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Thu, 3 Aug 2006 15:37:52 +0200 (CEST)
Whoops! yes. 73 Peter G3RZP _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps
/archives//html/Amps/2006-08/msg00088.html (7,338 bytes)

254. Re: [Amps] Grid Vs cathode drive (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Thu, 3 Aug 2006 18:20:53 +0200 (CEST)
most likely would have been built with a lower transmitting power.< I don't know about that, since before the FCC ruling, there were plenty of rigs with a pair of 6146s (of various varieties) around.
/archives//html/Amps/2006-08/msg00096.html (8,849 bytes)

255. Re: [Amps] Grid Vs cathode drive (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Fri, 4 Aug 2006 09:51:36 +0200 (CEST)
Looking back through my old (late 1950's and 1960's)ARRL handbooks, the 100watt rig was pretty standard - Heath, Hallicrafters, Collins. So I think it would have stayed pretty much that way, rather t
/archives//html/Amps/2006-08/msg00133.html (8,849 bytes)

256. Re: [Amps] Grid vs cathode driven (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Fri, 4 Aug 2006 10:13:44 +0200 (CEST)
I would be very dubious about the practicality of making the transformer. You're looking for a wideband transformer from about 13k ohm or so down to whatever, and that means a lot of primary inductan
/archives//html/Amps/2006-08/msg00134.html (7,547 bytes)

257. Re: [Amps] grid resonance (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Fri, 4 Aug 2006 10:23:21 +0200 (CEST)
g stage oscillate because the grid acts as a shield between the input and the output< If the grid resonance is high enough ( for example, a tube with a grid collett, and a grid 'cage' construction so
/archives//html/Amps/2006-08/msg00135.html (8,507 bytes)

258. Re: [Amps] Grid Vs cathode drive (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Fri, 4 Aug 2006 13:19:55 +0200 (CEST)
I thought they did originally - somewhere near the 70cms band. Lack of technology was a problem at the time, as I recall. (We're talking early 1950's) 73 Peter G3RZP _________________________________
/archives//html/Amps/2006-08/msg00138.html (8,177 bytes)

259. Re: [Amps] Grid vs cathode driven (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Fri, 4 Aug 2006 18:19:21 +0200 (CEST)
10 of them can be ran grid driven? The Galaxy amateur amp was a good example of this. I have built them using as high as 10 in G-G in parallel. No neutralization was necessary, and they ran just fine
/archives//html/Amps/2006-08/msg00143.html (7,517 bytes)

260. Re: [Amps] grid resonance (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sat, 5 Aug 2006 14:23:26 +0200 (CEST)
Actually, the GDO won't measure a parallel resonant circuit! Just consider what happens. We'll put a coil in parallel with a capacitor, and couple (magnetically) the GDO to the coil. The magnetic fie
/archives//html/Amps/2006-08/msg00180.html (8,884 bytes)

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