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Total 523 documents matching your query.

261. Re: [Amps] *** SPAM *** Re: Grid vs cathode driven (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sat, 5 Aug 2006 14:30:18 +0200 (CEST)
My book says that a pair of 811s need about 13k plate to plate load for full output in push pull. Four of them would be 7k plate to plate in push-pull parallel, but 1750 ohms in parallel. I thought y
/archives//html/Amps/2006-08/msg00181.html (6,783 bytes)

262. Re: [Amps] Grid Vs cathode drive (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 6 Aug 2006 08:08:02 +0200 (CEST)
watt pairs of 813's on 160.< 10 watt 807's wewre common over here - we had a 10 watt input limit on 160. One well known DXer had his '10watts' from no less than SIX 813's in push-pull parallel. He li
/archives//html/Amps/2006-08/msg00198.html (9,098 bytes)

263. Re: [Amps] grid resonance (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 6 Aug 2006 08:37:08 +0200 (CEST)
As I recall, that is done by determining the width of the dip and calculating what frequency points are at some reference level. < If you know what dip corresponds to the 3dB points, I can see that.
/archives//html/Amps/2006-08/msg00199.html (9,214 bytes)

264. Re: [Amps] grid resonance (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 6 Aug 2006 08:39:34 +0200 (CEST)
L to C ratio is very large. < Is that a general statement or one just applying to the mobile whip example? Sorry, Tom, but I don't understand: can you elucidate, please? 73 Peter G3RZP ______________
/archives//html/Amps/2006-08/msg00200.html (8,154 bytes)

265. [Amps] Resonance (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 6 Aug 2006 14:10:38 +0200 (CEST)
You can use a GDO to measure impedance, although you need some stuff to go with. Make a coupling loop fixture, so the coupling is constant: put the impedance to be measured across the loop, set GDO t
/archives//html/Amps/2006-08/msg00206.html (8,186 bytes)

266. Re: [Amps] Options (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 6 Aug 2006 14:24:02 +0200 (CEST)
Pappenfus describes a method matching tubes with varying the screen volts and having individual bias pots - in that example, 3 off 4CX250B. It should be possible to check emission by checking contact
/archives//html/Amps/2006-08/msg00207.html (7,646 bytes)

267. Re: [Amps] grid resonance (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 6 Aug 2006 23:40:39 +0200 (CEST)
of the other. When the remaining ends are joined, they are in Parallel.< Depends where the energy is injected. If it's across the circuit, then they're parallel. If it's induced into the coil, it has
/archives//html/Amps/2006-08/msg00233.html (8,423 bytes)

268. Re: [Amps] grid resonance (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 6 Aug 2006 23:48:28 +0200 (CEST)
RF into the coil from my GDO, I think you'll agree that it's a parallel circuit.< No. The current induced in the coil is in series with the coil. So the whole thing is a series resonant circuit. Or K
/archives//html/Amps/2006-08/msg00234.html (8,009 bytes)

269. Re: [Amps] grid resonance (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Mon, 7 Aug 2006 09:55:07 +0200 (CEST)
capacitance and/or inductance and/or resistance between the 'open' ends of a series L and C, so everything is a parallel circuit. The issue is whether it's significant.< All that does is complicate t
/archives//html/Amps/2006-08/msg00243.html (8,936 bytes)

270. Re: [Amps] grid resonance (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Mon, 7 Aug 2006 11:57:02 +0200 (CEST)
in that loop to understand what the frequency of the observed dip might be telling us about reverse feed-through from the anode back to the cathode.< Which is where a network analyser (another machin
/archives//html/Amps/2006-08/msg00246.html (8,306 bytes)

271. Re: [Amps] grid resonance (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Tue, 8 Aug 2006 11:08:30 +0200 (CEST)
Sorry, that's a typo - I meant super species. Come to think of it, maybe they're not mutant at all - after all, their body clocks are aligned to the One True Time.<< It's PDST at the moment, not PST!
/archives//html/Amps/2006-08/msg00280.html (8,581 bytes)

272. Re: [Amps] Checking for IMD (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sat, 12 Aug 2006 13:46:15 +0200 (CEST)
1.2 ghz rf head in it. < The oscillator that downconverts the first IF to 500MHz is about 1500MHz, and is free running. It's surprising that it manages the stability it does. One of these days, I'm g
/archives//html/Amps/2006-08/msg00437.html (8,241 bytes)

273. Re: [Amps] Checking for IMD (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 13 Aug 2006 00:02:34 +0200 (CEST)
PLL/DDS based synthesizer for this analyzer would be a really useful< Provided you keep the spurs down! Always a problem with DDS. What I do like about the 141 series is that it requires intelligence
/archives//html/Amps/2006-08/msg00448.html (9,798 bytes)

274. Re: [Amps] Checking for IMD (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Sun, 13 Aug 2006 08:54:59 +0200 (CEST)
not an averaging measurement device. I would add a correction that the level is not the average, but rather the peak power contained in the filter bandwidth.< Additionally, all too often, the 'S' in
/archives//html/Amps/2006-08/msg00455.html (8,966 bytes)

275. Re: [Amps] Anodizing aluminum, painting etc. (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Tue, 15 Aug 2006 08:21:14 +0200 (CEST)
If you had a heat sink of zero mass, infinite conductivity and zero thermal resistance btween sink and air, it would work perfectly, no matter what size it was. So mass itself doesn't matter: the imp
/archives//html/Amps/2006-08/msg00500.html (8,724 bytes)

276. Re: [Amps] Anodizing aluminum, painting etc. (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Wed, 16 Aug 2006 10:27:58 +0200 (CEST)
Will, I think that the big question is 'What is the dominant mode of heat transfer?' As for the availability of my infinite heat conductivity zero mass material, try the Sirius Cybernetics Corp in Ur
/archives//html/Amps/2006-08/msg00515.html (9,011 bytes)

277. Re: [Amps] Parasitics & Filament Sag (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Tue, 29 Aug 2006 10:52:12 +0200 (CEST)
There are a number of things I don't understand about the parasitic suppression business. According to Terman, a tuned amplifier with a plate circuit tuned LF of the grid circuit is unconditionally s
/archives//html/Amps/2006-08/msg00755.html (9,433 bytes)

278. Re: [Amps] *** SPAM *** Re: Parasitics & Filament Sag (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Tue, 29 Aug 2006 13:43:42 +0200 (CEST)
To see it, one converts the R/L suppressor's series R to Rp, its parallel-equivalent resistance -- which is what the anode sees at its VHF self-resonance. . This conversion is not a simple task.< The
/archives//html/Amps/2006-08/msg00759.html (8,453 bytes)

279. Re: [Amps] Heat spreader for solid-state amps (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Tue, 29 Aug 2006 17:08:29 +0200 (CEST)
Bear in mind that copper is a bit of #*@#%&*~ to work with. It tends to easily bind up drills and taps, so you really want to grind drills to have a bit of negative rake, although I can't grind drill
/archives//html/Amps/2006-08/msg00763.html (8,100 bytes)

280. Re: [Amps] TL-922 question (score: 1)
Author: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Date: Tue, 29 Aug 2006 18:01:37 +0200 (CEST)
In my experiences, they don't open, they short because the dielectric punches through.< I have had two ceramic tx caps go open - the voltage rating was OK, but the things heated up and burnt the silv
/archives//html/Amps/2006-08/msg00769.html (8,193 bytes)

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