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Total 614 documents matching your query.

361. Re: [Amps] Class C amp for RTTY contesting... (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Fri, 3 Nov 2006 02:48:59 -0500
I have a collection of old rigs. They certainly aren't that good. I don't have many waveform shots but here is a DX-60. http://www.w8ji.com/heathkit.htm I think the saving grace was receivers were s
/archives//html/Amps/2006-11/msg00052.html (8,427 bytes)

362. Re: [Amps] Class C amp for RTTY contesting... (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Fri, 3 Nov 2006 12:41:37 -0500
Valiant at: http://www.w8ji.com/valiant.htm This is the waveform of a modified unit. A stock unit is only a little better than a DX-60. I'll eventually get some shots of a 775DSP and other rigs as t
/archives//html/Amps/2006-11/msg00063.html (8,965 bytes)

363. Re: [Amps] AL-1200 Current Limit Relay Noise (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Fri, 3 Nov 2006 12:45:32 -0500
That is an AC relay, not a dc relay. That buzz sometimes comes from the mounting screw being too tight. Other than that or realigning the coil to the moving contact bar, the only choice is replacing
/archives//html/Amps/2006-11/msg00064.html (7,668 bytes)

364. Re: [Amps] AL-1200 Current Limit Relay Noise (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Fri, 3 Nov 2006 15:36:20 -0500
I thought you said it was the step start relay, if so it is AC. It is also a SPST. If it is simply the power line switching relay it is indeed a DC relay DPDT 30A. I don't know the relay number desi
/archives//html/Amps/2006-11/msg00066.html (7,992 bytes)

365. Re: [Amps] 822 and Johnson 211 Sockets (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Sat, 4 Nov 2006 14:49:23 -0500
It's a medium to low mu triode with 200 watts dissipation designed to run class B or C. About 1000-2000 volts anode depending on mode. I have an AM rig that uses a pair of them in push pull class C
/archives//html/Amps/2006-11/msg00068.html (6,698 bytes)

366. Re: [Amps] pi filter QBL 5/3500 (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Mon, 6 Nov 2006 15:03:55 -0500
Strays nomally subtract from the effective capacitance on 160. They add on higher bands, but the shunt reactance of the choke dominatates on 160 and 80 reducing effective capacitance....not that a Q
/archives//html/Amps/2006-11/msg00093.html (8,114 bytes)

367. Re: [Amps] FW: Zener Bias Replacement (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Mon, 6 Nov 2006 15:05:19 -0500
Good question. I always wonder about the stability of forward biased diodes with current and temperature. Has anyone actually measured it?? 73 Tom _______________________________________________ Amp
/archives//html/Amps/2006-11/msg00094.html (7,077 bytes)

368. Re: [Amps] Zener Bias Replacement (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Tue, 7 Nov 2006 05:35:17 -0500
That's why I always pick 5v Zeners for voltage references when possible. There's another issue with a string of diodes besides temperature. They change voltage with forward current. I'm sure diodes
/archives//html/Amps/2006-11/msg00100.html (8,399 bytes)

369. Re: [Amps] pi filter QBL 5/3500 (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Tue, 7 Nov 2006 08:53:06 -0500
Peter, People sometimes promise anything when selling an idea. The fact is there is NOTHING about the G2DAF system that helps IM distortion. It does not help linearity, it generally makes it worse.
/archives//html/Amps/2006-11/msg00102.html (9,842 bytes)

370. Re: [Amps] pi filter QBL 5/3500 (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Tue, 7 Nov 2006 19:10:56 -0500
There isn't much to figure. He probably just settled on the best circuit. 73 Tom _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mai
/archives//html/Amps/2006-11/msg00116.html (7,994 bytes)

371. Re: [Amps] Dentron Clipperton-L Questions (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Tue, 7 Nov 2006 22:35:55 -0500
The ALC system in the Dentron amps is terrible. It simply samples the cathode RF voltage, rectifies it with a power rectifier diode like a 1N4007, feeds a pot to the output. I'd never use it. Unplug
/archives//html/Amps/2006-11/msg00118.html (7,643 bytes)

372. Re: [Amps] class "A" RF amp question (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Wed, 8 Nov 2006 15:29:19 -0500
A linear amplifier is also sometimes called "efficiency modulation". What happens is this: 100% modulated AM requires PEP to be four times the carrier power. This occurs in a plate modulated class-C
/archives//html/Amps/2006-11/msg00127.html (10,029 bytes)

373. Re: [Amps] class "A" RF amp question (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Wed, 8 Nov 2006 19:05:21 -0500
Truer words were never spoken. Trying to get linear undistorted audio out of a plate modulated tetrode or pentode is almost a joke. It takes a low mu triode well into class C or some very special te
/archives//html/Amps/2006-11/msg00132.html (9,033 bytes)

374. Re: [Amps] AM On a linear (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Wed, 8 Nov 2006 23:50:15 -0500
and Frying the grid isn't the issue because heat is a time problem. The heavy grid conduction peaks are far too short unless you are using .05 CPS modulation or something. Even "pinching off" the ca
/archives//html/Amps/2006-11/msg00138.html (9,657 bytes)

375. Re: [Amps] Bandswitch lubricant & cleaner (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Fri, 10 Nov 2006 21:11:39 -0500
The units I have seen had bad servo motors. The grease inside was clogging them up. There isn't ANY safe lubricant to use on HV RF contacts. They should always be dry. You could lube the bushings an
/archives//html/Amps/2006-11/msg00147.html (7,271 bytes)

376. Re: [Amps] AL-572 Negative grid current? (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Sat, 11 Nov 2006 17:47:13 -0500
When the amp has a typical grid and plate current metering system in the B- return lead: 1.) Any short from the filament or cathode to ground causes the grid meter to read backwards. Always backward
/archives//html/Amps/2006-11/msg00151.html (7,633 bytes)

377. Re: [Amps] History of AMPS (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Tue, 14 Nov 2006 12:52:43 -0500
People tend to migrate towards what they are comfortable with. Some people like technical discussions, some people are not comfortable with the technical aspects of our hobby and enjoy the emotional
/archives//html/Amps/2006-11/msg00168.html (8,559 bytes)

378. Re: [Amps] History of AMPS (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Tue, 14 Nov 2006 16:19:06 -0500
To stay class A the amplifier always has to run at least twice the peak envelope power output as static dissipation. At least twice. So for class A, the answer is indeed 3000 watts (or more) standin
/archives//html/Amps/2006-11/msg00174.html (10,142 bytes)

379. Re: [Amps] Class A for AM (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Tue, 14 Nov 2006 21:05:48 -0500
That's the way I see it also. Since it should make around 50% on peaks it should make around 25% on carrier, and 3000 watts plus headroom of standing power should do it. It will just be useful outpu
/archives//html/Amps/2006-11/msg00180.html (9,346 bytes)

380. Re: [Amps] Class A for AM (score: 1)
Author: "Tom W8JI" <w8ji@w8ji.com>
Date: Wed, 15 Nov 2006 04:50:27 -0500
That does not apply to the AF signal content, or modulation. It only applies to the RF waveform and even-order distortion products of the RF signal. Push-pull cancels the even harmonic distortion of
/archives//html/Amps/2006-11/msg00195.html (8,595 bytes)

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