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Total 70 documents matching your query.

41. Re: [Amps] 3-500 to 4-250 conversion (score: 1)
Author: Jim Garland <4cx250b@muohio.edu>
Date: Thu, 16 Feb 2012 08:29:05 -1000
Hi Kennon, On the face of it, anyone who would build an amplifier using six 3-500zs, and then proceed to burn out all the tubes, pretty clearly wasn't knowledgable about the rudiments of power amplif
/archives//html/Amps/2012-02/msg00207.html (8,062 bytes)

42. Re: [Amps] Relay Suggestions Please (score: 1)
Author: "Jim Garland" <4cx250b@muohio.edu>
Date: Fri, 9 Mar 2012 09:28:54 -0700
Interesting comments in this thread. I checked a variety of PCB power relays for my StationPro controller and finally settled on the TE Connectivity/P&B model RTB14012F. (Mouser part number 655-RTB14
/archives//html/Amps/2012-03/msg00077.html (9,795 bytes)

43. Re: [Amps] How to know when filter caps begin to fail (score: 1)
Author: "Jim Garland" <4cx250b@muohio.edu>
Date: Wed, 28 Mar 2012 22:17:07 -0600
My experience is that the only time electrolytic caps explode is either when the polarity is backwards or when a rectifier diode fails and AC appears across them. I've found other age-related failure
/archives//html/Amps/2012-03/msg00343.html (8,249 bytes)

44. [Amps] Wanted: Gigavac Vacuum Relays G81A (score: 1)
Author: "Jim Garland" <4cx250b@muohio.edu>
Date: Mon, 23 Apr 2012 10:24:49 -0600
Hi all, I'd like to buy several Gigavac G81A vacuum relays, if anybody's got any to sell. The G81A is a PCB-mount relay, SPST NO contact, rated at 9KV/20A (depending on contact design, other currents
/archives//html/Amps/2012-04/msg00222.html (6,810 bytes)

45. Re: [Amps] Tubes vs. Solid State (score: 1)
Author: "Jim Garland" <4cx250b@muohio.edu>
Date: Tue, 1 May 2012 11:27:31 -0600
"As I recall, water can never exceed the boiling point temperature under normal atmospheric pressure. Additional heat does not raise water temperature but causes steam and steam too never increases b
/archives//html/Amps/2012-05/msg00014.html (8,967 bytes)

46. Re: [Amps] Ten-Tec 425 problem (score: 1)
Author: "Jim Garland" <4cx250b@muohio.edu>
Date: Wed, 13 Jun 2012 13:30:50 -0600
Hi Ray, Sorry to hear about your problem. It sounds like a flashover in the HV circuit, with the current surge burning out the plate choke. It might it have been an internal short in one of the tubes
/archives//html/Amps/2012-06/msg00093.html (10,077 bytes)

47. Re: [Amps] "babying" radios and tubes, can do or not? (score: 1)
Author: "Jim Garland" <4cx250b@muohio.edu>
Date: Thu, 14 Jun 2012 10:35:15 -0600
being the Leigh, I'm sure you didn't mean to convey the idea that a vacuum tube cathode is a reservoir containing a finite number of electrons which is eventually depleted. As I'm sure you know, the
/archives//html/Amps/2012-06/msg00112.html (9,278 bytes)

48. [Amps] question re 4:1 xfmr in QRO HF-2500DX (score: 1)
Author: "Jim Garland" <4cx250b@muohio.edu>
Date: Fri, 15 Jun 2012 09:48:26 -0600
Does anyone have construction and electrical details on the 4:1 transformer used in the tank circuit of the HF-2500DX amplifier? Number of turns, wire size, toroid size, core material, inductance, et
/archives//html/Amps/2012-06/msg00145.html (6,656 bytes)

49. [Amps] Pi-L Network Question (score: 1)
Author: "Jim Garland" <4cx250b@muohio.edu>
Date: Mon, 18 Jun 2012 09:56:38 -0600
I've been noodling around various tank circuit possibilities for a 160m monoband amplifier. A pi-L network isn't very practical for an 8877 because the relatively high plate impedance mandates very l
/archives//html/Amps/2012-06/msg00240.html (7,824 bytes)

50. Re: [Amps] Pi-L Network Question (score: 1)
Author: "Jim Garland" <4cx250b@muohio.edu>
Date: Mon, 18 Jun 2012 11:25:58 -0600
You're right, Peter. I misspoke. It's the large required L1 & L2 that make a pi-L impractical for an 8877 on 160m. For example, for Q=12 and a plate impedance of 2600 ohms (roughly correct for an 887
/archives//html/Amps/2012-06/msg00246.html (9,848 bytes)

51. [Amps] MHV HV VConnectors (score: 1)
Author: Jim Garland <4cx250b@muohio.edu>
Date: Sun, 24 Jun 2012 07:38:25 -0600
MHV connectors are an obsolete design and have largely been superseded by SHV connectors, which are safer. The center pin of an SHV connector is recessed so that it mates only after the shield is con
/archives//html/Amps/2012-06/msg00396.html (7,401 bytes)

52. [Amps] Passive Grid Input (score: 1)
Author: "Jim Garland" <4cx250b@muohio.edu>
Date: Thu, 9 Aug 2012 13:59:19 -0600
I'd think it would be better to use a 6dB pad to increase the drive requirements, so that the exciter always sees a 50 ohm load (neglecting reactive effects). Basically, one would have a 50 ohm resis
/archives//html/Amps/2012-08/msg00160.html (7,643 bytes)

53. [Amps] TL922A recommended mods? (score: 1)
Author: "Jim Garland" <4cx250b@muohio.edu>
Date: Tue, 14 Aug 2012 07:35:24 -0600
A friend has a recently acquired lightly used TL-922A that is unmodified and works perfectly on all bands. He has asked me to replace the clunky T/R relay with a quieter & faster vacuum relay, and al
/archives//html/Amps/2012-08/msg00198.html (7,970 bytes)

54. [Amps] Zener Screen Regulators (score: 1)
Author: "Jim Garland" <4cx250b@muohio.edu>
Date: Mon, 3 Sep 2012 11:15:20 -0600
supplying rated to the Bill, I'm not sure what you mean by a zener diode "supplying negative current." A zener diode doesn't supply any current at all, positive or negative. It sinks current while m
/archives//html/Amps/2012-09/msg00025.html (7,353 bytes)

55. Re: [Amps] Zener Screen Regulators (score: 1)
Author: "Jim Garland" <4cx250b@muohio.edu>
Date: Tue, 4 Sep 2012 20:12:58 -0600
flow. uphill. life ** negative charges are the direction of arbitrary. But it is the ** I can remember hearing debates on this subject fifty years ago, so I doubt it will be settled now. However, fo
/archives//html/Amps/2012-09/msg00048.html (12,176 bytes)

56. [Amps] Physics 101 - Charges, Electric Fields, and Currents (score: 1)
Author: "Jim Garland" <4cx250b@muohio.edu>
Date: Thu, 6 Sep 2012 12:28:10 -0600
I'd like to try and clear up a few misconceptions about charges and currents. As most of you know, physicist J.C. Maxwell in 1861 published the four equations bearing his name that described the prop
/archives//html/Amps/2012-09/msg00089.html (11,204 bytes)

57. Re: [Amps] Zener Screen Regulators (score: 1)
Author: "Jim Garland" <4cx250b@muohio.edu>
Date: Sat, 8 Sep 2012 08:18:03 -0600
"That's halfways right, but I still just don't see the need of even talking about the motion of positive charges. Talking about motion of negatively charged electrons is enough in electronics. Why o
/archives//html/Amps/2012-09/msg00127.html (10,351 bytes)

58. Re: [Amps] SOURCE OF TURNS COUNTER(S) - US SUPPLIERS (score: 1)
Author: "Jim Garland" <4cx250b@muohio.edu>
Date: Tue, 11 Sep 2012 11:26:12 -0600
Re Kintronix turns counters, the body of the counters look like the common type on vintage military gear, spruced up (or not, depending on your taste) with a knurled aluminum knob. Does the company a
/archives//html/Amps/2012-09/msg00232.html (8,541 bytes)

59. Re: [Amps] load testing HV Power supplies (score: 1)
Author: "Jim Garland" <4cx250b@muohio.edu>
Date: Tue, 25 Sep 2012 10:29:38 -0600
To test, say, a 4000V@ 1Amp HV power supply requires a 4000 ohm/4000W resistor, which you're unlikely to find in your junk box! As a practical matter, the only way to test such a power supply is with
/archives//html/Amps/2012-09/msg00291.html (8,071 bytes)

60. [Amps] Novel Screen Grid Regulator (score: 1)
Author: "Jim Garland" <4cx250b@muohio.edu>
Date: Thu, 27 Sep 2012 08:48:50 -0600
Hi Gang, I'm designing a 160m monoband amplifier using three GU-74B tetrodes and thought a few of you might be interested in reading about a clever screen grid voltage regulator circuit I stumbled ac
/archives//html/Amps/2012-09/msg00305.html (12,899 bytes)

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