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21. RE: [Amps] please help with weird problem - culprit found (score: 1): Author: "Joe Subich, K4IK" <k4ik@subich.com>; Date: Mon, 31 Jan 2005 12:20:04 -0500; Not only is the "problem" well known with the 765 ... it exists in all of the Icom radios, the Yaesu FT-1000 series radios, and most other rigs that provide provisions for either an external receive; /archives//html/Amps/2005-01/msg00645.html (8,669 bytes)
22. RE: [Amps] Plate impedance formula (score: 1): Author: "Joe Subich, K4IK" <k4ik@subich.com>; Date: Sun, 6 Feb 2005 10:20:06 -0500; As far as the plate tank is concerned, the plate impedance is the total plate current (current drawn by both tubes or two times the current drawn by a single tube) and the plate voltage common to bo; /archives//html/Amps/2005-02/msg00195.html (7,611 bytes)
23. Re: [Amps] [AMPS] Re: FL-2100B Failure (score: 1): Author: "Joe Subich, K4IK" <k4ik@subich.com>; Date: Tue, 22 Feb 2005 18:10:09 -0500; These two observations point not to parasitics but an attempt to operate the amplifier on a band for which it was not designed perhaps 17, 12 or 11 meters. Burning in certain areas of the plate choke; /archives//html/Amps/2005-02/msg00675.html (7,844 bytes)
24. Re: [Amps] AL-1200 vs AL-1500 (score: 1): Author: "Joe Subich, K4IK" <k4ik@subich.com>; Date: Thu, 24 Feb 2005 19:45:27 -0500; The one problem with the AL-1500 is the sensitivity of the 8877 to changes in the load. K8CC has written several times about problems with high grid current as the load changes with multiple antennas; /archives//html/Amps/2005-02/msg00792.html (8,649 bytes)
25. Re: [Amps] SB-220 Bandswitches (score: 1): Author: "Joe Subich, K4IK" <k4ik@subich.com>; Date: Fri, 25 Feb 2005 11:47:20 -0500; He suffered significant damage from ice and water during the ice storms that hit the Midwest and Great Lakes area about eight weeks ago. Since this comes shortly after a relocation, I suspect these; /archives//html/Amps/2005-02/msg00809.html (7,068 bytes)
26. Re: [Amps] TS-850 Output (score: 1): Author: "Joe Subich, K4IK" <k4ik@subich.com>; Date: Fri, 25 Feb 2005 13:32:12 -0500; Before turning up the output power on ANY solid state radio, please look up the manufacturer's specs for the PA device. For example, there are those who recommend running the FT-1000 Field at 150 Wat; /archives//html/Amps/2005-02/msg00822.html (8,374 bytes)
27. Re: [Amps] TS-850 Output (score: 1): Author: "Joe Subich, K4IK" <k4ik@subich.com>; Date: Fri, 25 Feb 2005 14:21:44 -0500; That may be so ... the 2SC2879 is rated for 12 to 18 volts. However, my point is one cannot simply crank up the output power without concern for the other occupants of the band. It is imperative that; /archives//html/Amps/2005-02/msg00826.html (7,969 bytes)
28. Re: [Amps] Water cooled amp question (score: 1): Author: "Joe Subich, K4IK" <k4ik@subich.com>; Date: Sat, 5 Mar 2005 17:16:37 -0500; Water (pure, distilled) has the higher specific heat (e.g., absorbs more heat per unit) than ethylene glycol. When I was running UHF TV transmitters, in some cases where the heat exchanger was margi; /archives//html/Amps/2005-03/msg00121.html (8,828 bytes)
29. Re: [Amps] water cooled... (score: 1): Author: "Joe Subich, K4IK" <k4ik@subich.com>; Date: Sun, 6 Mar 2005 00:30:36 -0500; This is true in a pressurized system like an automobile engine. Unless designed specifically for vapor phase cooling (e.g., with a boiler), water cooled tubes should not be operated above 180 degrees; /archives//html/Amps/2005-03/msg00144.html (8,067 bytes)
30. Re: [Amps] Water cooled amp question (score: 1): Author: "Joe Subich, K4IK" <k4ik@subich.com>; Date: Sun, 6 Mar 2005 00:30:36 -0500; Not in that transmitter ... the cooling system contained about 100 gallons each. The transmitter was in an unheated building, the reservoirs were stainless steel and uninsulated, the pipes were unins; /archives//html/Amps/2005-03/msg00145.html (9,046 bytes)
31. Re: [Amps] water and vapor phase tube cooling (score: 1): Author: "Joe Subich, K4IK" <k4ik@subich.com>; Date: Sun, 6 Mar 2005 00:45:43 -0500; There was some abnormal additive in that ethylene glycol if you received chemical burns from it. I was regularly doused with the 50-50 glycol/water solution when working with the TV transmitter cooli; /archives//html/Amps/2005-03/msg00146.html (8,093 bytes)
32. Re: [Amps] Yaesu FL-2100B failure (grid resistor caps) (score: 1): Author: "Joe Subich, K4IK" <k4ik@subich.com>; Date: Sun, 6 Mar 2005 10:17:19 -0500; Or the amplifier has been badly overdriven/drawn excessive grid current for a long time. Perhaps, there has also been DC current through those resistors due to the capacitor problem below. It' possib; /archives//html/Amps/2005-03/msg00157.html (10,125 bytes)
33. Re: [Amps] Water cooled amp question (score: 1): Author: "Joe Subich, K4IK" <k4ik@subich.com>; Date: Sun, 6 Mar 2005 10:32:24 -0500; One could certainly use one (or two) water heater elements in the supply reservoir. The primary problem location is the heat exchanger ... it's large effective surface area and relatively small, rela; /archives//html/Amps/2005-03/msg00158.html (9,422 bytes)
34. Re: [Amps] FW: RE: Liquid Cooling Systems (score: 1): Author: "Joe Subich, K4IK" <k4ik@subich.com>; Date: Thu, 10 Mar 2005 23:42:46 -0500; Neither do I see a problem. Fact is, by this time next year I expect to see a water cooled solid state amplifier available at Dayton. There should be some 120 - 200 volt transistors available at a re; /archives//html/Amps/2005-03/msg00277.html (8,775 bytes)
35. Re: [Amps] FW: RE: Liquid Cooling Systems (score: 1): Author: "Joe Subich, K4IK" <k4ik@subich.com>; Date: Fri, 11 Mar 2005 12:52:03 -0500; To bring this back to water cooled tubes ... one can't raise the pressure for two reasons. The systems are generally run unpressurized and there is still a limit to the safe temperature for the seals; /archives//html/Amps/2005-03/msg00288.html (8,882 bytes)
36. Re: [Amps] Even more power solid-state amp's (score: 1): Author: "Joe Subich, K4IK" <k4ik@subich.com>; Date: Thu, 31 Mar 2005 14:32:49 -0500; The TV transmitters typically run 50 KW peak power (Sync & black). A few will go to 100 KW, generally with two 50 KW transmitters in parallel. The cards are typically two amplifiers (50 Volt) in push; /archives//html/Amps/2005-03/msg00746.html (8,229 bytes)
37. Re: [Amps] Even more power solid-state amp's (score: 1): Author: "Joe Subich, K4IK" <k4ik@subich.com>; Date: Fri, 1 Apr 2005 09:53:51 -0500; The cost of a "hot standby" transmitter using vacuum tubes is far higher than just the tube alone. It really is a completely separate transmitter with the exception of, perhaps, the lowlevel stages.; /archives//html/Amps/2005-04/msg00011.html (7,585 bytes)
38. Re: [Amps] Low Pass Filters (score: 1): Author: "Joe Subich, K4IK" <k4ik@subich.com>; Date: Mon, 4 Apr 2005 11:24:24 -0400; Unless you plan to modulate that amplifier, you will need bias for AM service (amplification of low level AM). If you don't bias it to at least AB you will have a disaster on your hands. 73, ... Joe,; /archives//html/Amps/2005-04/msg00074.html (7,276 bytes)
39. Re: [Amps] a common topic here tspa (score: 1): Author: "Joe Subich, K4IK" <k4ik@subich.com>; Date: Tue, 5 Apr 2005 11:21:24 -0400; In essence, if the 8877 is installed as designed - with the grid grounded directly all the way around with the proper "ring" of finger stock, the tube will not oscillate. If, the grid is grounded usi; /archives//html/Amps/2005-04/msg00102.html (8,151 bytes)
40. Re: [Amps] a common topic here tspa (score: 1): Author: "Joe Subich, K4IK" <k4ik@subich.com>; Date: Tue, 5 Apr 2005 16:00:27 -0400; As I recall, and it has more than 20 years since I was able to set down with some of the best tube guys at Eimac over beers (while we were taming "experimental" UHF TV transmitters). Since all of us; /archives//html/Amps/2005-04/msg00111.html (9,455 bytes)

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