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361. Re: [Amps] Caps across rectifier diodes test (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Wed, 4 Mar 2009 20:59:36 -0500; The only time that I have seen hash from diodes was in a power supply that I built to power a BC453 receiver with a converter ahead of it. The power transformer I used had too high a voltage so I use; /archives//html/Amps/2009-03/msg00125.html (12,673 bytes)
362. Re: [Amps] An Extra Thank You! (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Thu, 5 Mar 2009 16:17:54 -0500; Good to see it working Scott! If you remember these two numbers you can get in the ball park on db gain or loss easily: 2x the power = 3 db. 10x the power = 10 db. You have 20 watts in so 10 times th; /archives//html/Amps/2009-03/msg00170.html (10,679 bytes)
363. Re: [Amps] An Extra Thank You! (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Thu, 5 Mar 2009 16:45:59 -0500; Yes drive power does need to be considered when figuring efficiency of a grounded grid amp as part of the drive power does pass thru the amp. But, not all of the drive power appears in the output of; /archives//html/Amps/2009-03/msg00177.html (9,815 bytes)
364. Re: [Amps] An Extra Thank You! (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Thu, 5 Mar 2009 17:40:07 -0500; I think this is getting done kind of backwards. I believe the correct way to figure efficiency is power output minus drive power that is fed thru, divided by plate input power (plate current times pl; /archives//html/Amps/2009-03/msg00185.html (10,372 bytes)
365. Re: [Amps] A Symptom of Low Bias? (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Fri, 6 Mar 2009 14:49:57 -0500; Hi Scott, It sounds like you are way overdriving the amp. When tuning up do not increase the drive any more when you have obtained maximum output from the amp. Never mind if the grid current is lower; /archives//html/Amps/2009-03/msg00215.html (10,848 bytes)
366. Re: [Amps] A Symptom of Low Bias? (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Fri, 6 Mar 2009 14:52:34 -0500; Forgot to mention the bias. I don't know what the ZSAC (idle plate current) should be on that tube but it sound in the ball park. Usually idle current will be around 1/3 of full plate current +- depe; /archives//html/Amps/2009-03/msg00216.html (10,012 bytes)
367. Re: [Amps] A Symptom of Low Bias? (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Fri, 6 Mar 2009 15:27:46 -0500; A peak reading wattmeter would work ok too. As to the grid current it could be a few things. I looked at your schematic on you web site and noticed that the lead coming from the cathode that gets gro; /archives//html/Amps/2009-03/msg00219.html (14,251 bytes)
368. Re: [Amps] HV measurements (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Mon, 9 Mar 2009 18:06:13 -0400; Fluke 80-K6 is what you need. Several on ebay for around $50.00 73 Gary K4FMX _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman; /archives//html/Amps/2009-03/msg00264.html (8,519 bytes)
369. Re: [Amps] Choosing a Plate Transformer (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Tue, 10 Mar 2009 13:31:42 -0400; Hi Scott, Here are some numbers to keep in mind when transformer shopping. The full load voltage with a bridge rectifier will be 1.25 x the transformer ac voltage. With a doubler it will be 2.5 times; /archives//html/Amps/2009-03/msg00285.html (12,106 bytes)
370. Re: [Amps] Choosing a Plate Transformer (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Tue, 10 Mar 2009 13:41:42 -0400; I think that the GI7B has a 350 watt plate dissipation. 1500 watts input at 60% efficiency = 900 watts out. 1500 -900 = 600 watts of plate dissipation! The tube will cook. 73 Gary K4FMX _____________; /archives//html/Amps/2009-03/msg00286.html (12,465 bytes)
371. Re: [Amps] Choosing a Plate Transformer (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Tue, 10 Mar 2009 14:26:07 -0400; 2500 volts at 600 ma = 1500 watts input. You said it! :>) 73 Gary K4FMX _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/list; /archives//html/Amps/2009-03/msg00291.html (15,256 bytes)
372. Re: [Amps] Choosing a Plate Transformer (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Tue, 10 Mar 2009 20:53:35 -0400; The "2500v @ 600ma" doesn't necessarily mean at the same time. Lots of spec sheets will show maximum voltage and maximum current but that is often an either or rating. If you ran the tube at 850 watt; /archives//html/Amps/2009-03/msg00300.html (9,636 bytes)
373. Re: [Amps] Odd efficiency shift on 80m band (score: 1): Author: garyschafer@comcast.net; Date: Thu, 12 Mar 2009 18:24:59 +0000 (UTC); Hi Jeff, You didn't tell us how much grid current there was in each part of the band for each test. You also seem to have the amp loaded heavier where the efficiency is lower, you are running more po; /archives//html/Amps/2009-03/msg00352.html (12,199 bytes)
374. Re: [Amps] 4100VD 3CPX1500A7 (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Thu, 19 Mar 2009 12:46:54 -0400; Can you point us to an 80 - 10 YC-156 amp that does this? I haven't seen one anywhere with a tube with that much capacitance. I have seen a YC-156 on 6 meters but it used no plate tune capacitor at a; /archives//html/Amps/2009-03/msg00488.html (11,364 bytes)
375. Re: [Amps] screen grid current question on gu-84b (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Sat, 18 Apr 2009 13:02:37 -0400; It depends on the particular type of tube used. With a 4CX1000 I experienced similar readings to what Bill notes. However when the screen current was in the negative region, tuning the plate tuning w; /archives//html/Amps/2009-04/msg00166.html (10,680 bytes)
376. Re: [Amps] tank calculations - MFJ analizer - resistor (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Tue, 21 Apr 2009 11:18:29 -0400; Yes leave the tube in! You want the capacitance of the tube in the circuit as well as all the other components that are normally in the circuit. Just put the resistor from plate to ground in a short; /archives//html/Amps/2009-04/msg00178.html (8,510 bytes)
377. Re: [Amps] High SWR, (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Wed, 22 Apr 2009 22:28:26 -0400; Well, spouting off can be a good thing. That's what the reflector is for. So people can learn from one another. Plus it provides some entertainment for us old farts. 73 Gary K4FMX ___________________; /archives//html/Amps/2009-04/msg00230.html (10,320 bytes)
378. Re: [Amps] High SWR, (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Thu, 23 Apr 2009 12:00:52 -0400; I am curious as to why you would say that "reflected power is not real"? Just because reflected power upsets the readings of a wattmeter such as a bird or telewave, and you have to make a correction; /archives//html/Amps/2009-04/msg00262.html (11,651 bytes)
379. Re: [Amps] High SWR (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Thu, 23 Apr 2009 12:26:14 -0400; Reflected power is not best expressed as reactive power. It is real power and it is not lost power just because it is reflected. when reflected power sees the matching network in the final amp or an; /archives//html/Amps/2009-04/msg00267.html (9,844 bytes)
380. Re: [Amps] High SWR, (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Thu, 23 Apr 2009 18:31:36 -0400; I have read this about 4 times and I still can't figure out what you are saying. "there is no such thing as reflected power but, oh wait, we can measure reflected power just like real power but the r; /archives//html/Amps/2009-04/msg00294.html (16,256 bytes)

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