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21. Re: [Amps] 572b (score: 1)
Author: MU 4CX250B <4cx250b@miamioh.edu>
Date: Thu, 2 May 2013 16:32:00 -0600
I'm afraid I don't understand why the plate dissipation would affect longevity, provided the tubes have adequate cooling. Exceeding rated grid current or plate current, or using the wrong filament vo
/archives//html/Amps/2013-05/msg00022.html (11,089 bytes)

22. Re: [Amps] Tuned Output Network for gs35-b (score: 1)
Author: "Jim Garland" <4cx250b@miamioh.edu>
Date: Tue, 28 May 2013 09:57:05 -0600
Mel, The nature of your questions suggests you should probably did into the literature (e.g., the ARRL Handbook) a bit before moving forward too far with construction. To start, you should probably c
/archives//html/Amps/2013-05/msg00193.html (9,725 bytes)

23. Re: [Amps] Advice needed for SS amp (score: 1)
Author: MU 4CX250B <4cx250b@miamioh.edu>
Date: Wed, 5 Jun 2013 19:42:37 -0600
Seems to me the 50V limit would be a deal breaker. I love the idea of a transformerless design. I wonder if the THP problems were really the devices, as opposed to a design glitch they never figured
/archives//html/Amps/2013-06/msg00058.html (11,377 bytes)

24. Re: [Amps] Advice needed for SS amp (score: 1)
Author: "Jim Garland" <4cx250b@miamioh.edu>
Date: Thu, 6 Jun 2013 07:06:02 -0600
I could be wrong, but I doubt Peltier coolers would be a very practical solution. The typical ones on eBay or at surplus outlets are basically slabs of a thermelectric material between two metal plat
/archives//html/Amps/2013-06/msg00098.html (11,530 bytes)

25. Re: [Amps] Solid state amplifier cooling (score: 1)
Author: MU 4CX250B <4cx250b@miamioh.edu>
Date: Thu, 6 Jun 2013 09:15:54 -0600
Interesting idea, Bill. I wonder if folks on the reflector have tried vapor phase cooling? In principle, that should be the most effective cooling scheme of all, given the high latent heat of vaporiz
/archives//html/Amps/2013-06/msg00109.html (11,202 bytes)

26. Re: [Amps] The Pin One Problem (score: 1)
Author: "Jim Garland" <4cx250b@miamioh.edu>
Date: Thu, 6 Jun 2013 11:49:48 -0600
I realize we're straying rather far afield from amplifier topics, so pse overlook my wading into the discussion. The proliferation of outboard audio devices for transceivers, and the desire to mix an
/archives//html/Amps/2013-06/msg00125.html (11,353 bytes)

27. Re: [Amps] The Pin One Problem (score: 1)
Author: "Jim Garland" <4cx250b@miamioh.edu>
Date: Fri, 7 Jun 2013 16:55:47 -0600
Joe, I'm not sure why you think the StationPro causes problems in interfacing to amateur equipment. The problems a few StationPro builders have encountered with hum in their microphone circuits have
/archives//html/Amps/2013-06/msg00169.html (22,605 bytes)

28. Re: [Amps] The Pin One Problem - Common Impedance Coupling (score: 1)
Author: "Jim Garland" <4cx250b@miamioh.edu>
Date: Fri, 7 Jun 2013 17:12:17 -0600
Jim, I think your writeup is excellent. The only point I would disagree with you about is your assertion that "ground loop" refers only to magnetic coupling. This is just a matter of nomenclature, of
/archives//html/Amps/2013-06/msg00170.html (14,576 bytes)

29. Re: [Amps] why a tube fails ? (score: 1)
Author: "Jim Garland" <4cx250b@miamioh.edu>
Date: Tue, 27 Aug 2013 21:00:50 -0600
Hi Charles, Very intersesting questions! I can't help you with your question about tube failure modes, though I know at least one mode with indirectly heated cathode tubes is that excessive cathode c
/archives//html/Amps/2013-08/msg00135.html (16,875 bytes)

30. Re: [Amps] Hole Flow (score: 1)
Author: "Jim Garland" <4cx250b@miamioh.edu>
Date: Wed, 28 Aug 2013 18:03:55 -0600
Sorry guys, but I can't resist weighing in on this topic one more time. Variations on this thread (hole vs. electron conduction, direction of current flow, etc.) pop up occasionally on the reflector
/archives//html/Amps/2013-08/msg00168.html (14,479 bytes)

31. [Amps] FW: Electron HOLE flow (score: 1)
Author: "Jim Garland" <4cx250b@miamioh.edu>
Date: Wed, 28 Aug 2013 20:23:43 -0600
Roger, the speed you're referring to is called the "drift velocity" of electrons in a metal. The drift velocity is very slow, only about 1 meter per hour. That's not the actual speed of the electrons
/archives//html/Amps/2013-08/msg00171.html (10,947 bytes)

32. Re: [Amps] Hole Flow (score: 1)
Author: "Jim Garland" <4cx250b@miamioh.edu>
Date: Sat, 31 Aug 2013 19:48:47 -0600
This thread reminds me of the neverending debate about whether lightning jumps from the cloud to the ground, or from the ground to the cloud! (I have heard it can go either way, depending on the type
/archives//html/Amps/2013-08/msg00197.html (13,377 bytes)

33. Re: [Amps] design approach for QRO solid state (score: 1)
Author: "Jim Garland" <4cx250b@miamioh.edu>
Date: Thu, 12 Sep 2013 07:36:32 -0600
Roger, That's a fabulous tutorial. Thanks very much! Jim Garland W8ZR compounds. system. properly _______________________________________________ Amps mailing list Amps@contesting.com http://lists.co
/archives//html/Amps/2013-09/msg00070.html (16,893 bytes)

34. [Amps] Workshop Danger (score: 1)
Author: "Jim Garland" <4cx250b@miamioh.edu>
Date: Fri, 13 Sep 2013 06:24:16 -0600
My least favorite part of homebrewing an amplifier is making the meter cutouts and tube socket holes. Last evening I cut three 2.90 holes for GU-74Bs and survived the experience. I have a set of hole
/archives//html/Amps/2013-09/msg00106.html (7,943 bytes)

35. Re: [Amps] Workshop Danger (score: 1)
Author: "Jim Garland" <4cx250b@miamioh.edu>
Date: Fri, 13 Sep 2013 07:11:11 -0600
Peter, Thanks for the great tip, re securing Jacob's chucks. I agree completely that using a vertical mill is by far the best solution. I've got a mill, but unfortunately it's a small one designed fo
/archives//html/Amps/2013-09/msg00110.html (10,633 bytes)

36. [Amps] Plate Choke Query (score: 1)
Author: "Jim Garland" <4cx250b@miamioh.edu>
Date: Sat, 14 Sep 2013 07:09:38 -0600
I'm making a plate choke for a duoband 80m-160m amplifier and want to solicit any comments. The tank compartment is space-limited, and at most I can have 4 inches of winding length on a 1 inch diamet
/archives//html/Amps/2013-09/msg00160.html (7,884 bytes)

37. Re: [Amps] Rectifier equilization? (score: 1)
Author: "Jim Garland" <4cx250b@miamioh.edu>
Date: Sun, 15 Sep 2013 13:54:38 -0600
Although it is made by GE, I believe the CL-90 is not a surge suppressor, but an inrush current limiter. It's probably an MOV of some sort, but not the type normally used for surge suppression. When
/archives//html/Amps/2013-09/msg00187.html (13,489 bytes)

38. Re: [Amps] More on two pin 220vac (score: 1)
Author: "Jim Garland" <4cx250b@miamioh.edu>
Date: Tue, 15 Oct 2013 07:12:12 -0600
Paul has raised a pertinent issue. I find it hard to believe that the power distribution in Thailand or any other country is completely floating with respect to ground. Were that the case, then the e
/archives//html/Amps/2013-10/msg00252.html (9,506 bytes)

39. Re: [Amps] Even More on two pin 220vac (score: 1)
Author: MU 4CX250B <4cx250b@miamioh.edu>
Date: Tue, 15 Oct 2013 09:20:21 -0600
Charly, I suggest you inspect the circuit breaker box at the service entrance to your house and see if the incoming neutral line is connected to a ground rod. if not, then I recommend you drive an 8
/archives//html/Amps/2013-10/msg00261.html (13,631 bytes)

40. Re: [Amps] Alpha 76A - 120hz hum on 160m only (score: 1)
Author: "Jim Garland" <4cx250b@miamioh.edu>
Date: Fri, 18 Oct 2013 09:31:05 -0600
FYI, for my 80m/160m duoband amp (2500V, three GU-74Bs), below the "main" 200uH plate choke, I'm using a supplementary 62 uH choke wound on a ferrite core and bypassed at the cold end with a Sprague
/archives//html/Amps/2013-10/msg00325.html (10,478 bytes)

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