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321. Re: [Amps] crossmodulation in PA ? Thanks for all good??advice (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Fri, 7 Sep 2007 18:37:09 -0500; The myth has not been dispelled. :>) The purpose of a bonding wire around the rotator is to reduce the voltage that the rotator sees when lightning hits the mast and conducts current thru the rotator; /archives//html/Amps/2007-09/msg00096.html (8,781 bytes)
322. Re: [Amps] Need some help (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Fri, 7 Sep 2007 20:46:29 -0500; It sounds like the cathode circuit has a short to ground. 73 Gary K4FMX _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listi; /archives//html/Amps/2007-09/msg00100.html (10,564 bytes)
323. Re: [Amps] 4CX250 IMD (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Sat, 29 Sep 2007 21:43:45 -0500; You guys are not reading the spec sheets right. As to power at different voltages, they show a maximum plate current of 250 ma at 1500 volts and also at 2000 volts. Of course power is greater at the; /archives//html/Amps/2007-09/msg00501.html (14,184 bytes)
324. Re: [Amps] 4CX250 IMD (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Sun, 30 Sep 2007 23:18:27 -0500; Hi Carl, I haven't looked at the 4cx250 sheets in a long time so I just looked at the 4cx250B Eimac, 4cx250B STC and 4cx250R Eimac data sheets. Power should be referred to as PEP and average power,; /archives//html/Amps/2007-10/msg00000.html (9,361 bytes)
325. Re: [Amps] 8877 Filament choke (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Thu, 15 Nov 2007 18:18:54 -0600; so the cathode should be connected to the filament circuit. Should there be a glitch a cathode choke could open and destroy the tube via a cathode filament short. 73 Gary K4FMX _____________________; /archives//html/Amps/2007-11/msg00216.html (11,701 bytes)
326. Re: [Amps] High voltage power supply for linear amp (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Wed, 2 Jan 2008 12:49:13 -0500; The reverse voltage on each diode leg is approximately equal to the TOTAL transformer peak voltage whether it is a full wave or bridge. The diode current requirements will be the same for full wave o; /archives//html/Amps/2008-01/msg00015.html (10,285 bytes)
327. Re: [Amps] HV Supplies and Diodes (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Wed, 2 Jan 2008 15:28:01 -0500; Since all modern diodes have an avalanche region for reverse current protection, placing resistors across diodes in a string can only make matters worse. Without resistors, current will be the same a; /archives//html/Amps/2008-01/msg00018.html (9,605 bytes)
328. Re: [Amps] HV Supplies and Diodes (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Thu, 3 Jan 2008 18:50:32 -0500; The 1980 ARRL handbook section on power supplies does recommend using resistors across each diode in a string. The 2000 ARRL handbook recommends NOT using resistors across each diode in a string. Tim; /archives//html/Amps/2008-01/msg00049.html (19,658 bytes)
329. Re: [Amps] questions about hi pot tester (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Thu, 3 Jan 2008 19:05:47 -0500; Don't overlook the AC hi pot testers on ebay that are usually dirt cheap compared to the DC units. I picked an AC unit up for $15.00 or $20.00. All you need to do is make a simple voltage doubler, Tr; /archives//html/Amps/2008-01/msg00050.html (11,819 bytes)
330. Re: [Amps] HV Supplies and Diodes (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Thu, 3 Jan 2008 23:22:43 -0500; The reverse current will be set by the sum of the leakage resistance of ALL of the diodes in the string that are not in avalanche. The current will be the same in all the diodes, they are in series.; /archives//html/Amps/2008-01/msg00054.html (9,627 bytes)
331. Re: [Amps] Warm up time for SB-200? (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Wed, 23 Jan 2008 19:32:03 -0500; What will make it better after 30 seconds than what it would be after a second or two of turning on the power switch? 73 Gary K4FMX _______________________________________________ Amps mailing list A; /archives//html/Amps/2008-01/msg00161.html (9,056 bytes)
332. Re: [Amps] Step start (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Sun, 3 Feb 2008 11:35:14 -0500; As David said step starts circuits are simple. There is no need for a timer etc. In a couple of supplies that I have I just place a low value resistor in series with the mains and place the relay coi; /archives//html/Amps/2008-02/msg00013.html (10,825 bytes)
333. Re: [Amps] XCVR Output vs. Amplifier Input Impedence (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Sun, 9 Mar 2008 15:43:12 -0400; The source impedance (output impedance of the transceiver) has no bearing on the input SWR of the amplifier. Anything that you do to the source impedance won't change the SWR at the amp input circuit; /archives//html/Amps/2008-03/msg00099.html (10,196 bytes)
334. Re: [Amps] XCVR Output vs. Amplifier Input Impedence (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Sun, 9 Mar 2008 16:09:35 -0400; Huh? Never heard of lumped elements? Do you think you actually measure SWR on a transmission line with an SWR bridge or a reflected power meter? 73 Gary K4FMX _______________________________________; /archives//html/Amps/2008-03/msg00102.html (8,094 bytes)
335. Re: [Amps] Looking for a mica capacitor (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Thu, 13 Mar 2008 20:45:21 -0400; If it is for the tuned input circuit you should be able to use just about any silver mica capacitors in there. That is all most other amps like the heath sb200 use in the same circuit. 73 Gary K4FMX; /archives//html/Amps/2008-03/msg00115.html (9,287 bytes)
336. Re: [Amps] Power transformer for 600 watt rig (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Mon, 17 Mar 2008 19:47:28 -0400; You need to first define what the 600 watt rig is. SSB PEP power or an AM rig. What kind of voltage regulation do you need/want. Full wave voltage doubler or full wave bridge, capacitor or choke inpu; /archives//html/Amps/2008-03/msg00155.html (8,674 bytes)
337. Re: [Amps] Power transformer for 600 watt rig (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Tue, 18 Mar 2008 11:08:59 -0400; Hi Jim, No I don't have LTspice. What I was saying about what type of service the power supply is to expect to see matters a great deal. A transformer (a good one) that is to be used with a voltage d; /archives//html/Amps/2008-03/msg00163.html (8,621 bytes)
338. Re: [Amps] Power transformer for 600 watt rig (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Tue, 18 Mar 2008 15:14:54 -0400; Hi Pat, The biggest problem with a choke input filter is the transient response of the choke with SSB. It will allow the voltage to dip quite a bit on some of the voice peaks as the amplifier demands; /archives//html/Amps/2008-03/msg00169.html (12,525 bytes)
339. Re: [Amps] Power transformer for 600 watt rig (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Tue, 18 Mar 2008 20:21:29 -0400; Filtering isn't the problem. Dynamic regulation is a problem with a choke. You get severe voltage drops when current is drawn at an audio rate from the power supply. A swinging choke is even worse th; /archives//html/Amps/2008-03/msg00174.html (17,742 bytes)
340. Re: [Amps] Power transformer for 600 watt rig (score: 1): Author: "Gary Schafer" <garyschafer@comcast.net>; Date: Wed, 19 Mar 2008 11:50:07 -0400; The same problems exist with either. However with a modulator, often it is powered from the same supply as the finals are and there is a heavy static load on the power supply. The percentage of curr; /archives//html/Amps/2008-03/msg00177.html (14,055 bytes)

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