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121. Re: [Amps] Clipperton-L question (score: 1): Author: Vic K2VCO <k2vco.vic@gmail.com>; Date: Thu, 12 Sep 2013 13:53:42 -0700; They certainly have a lot of contact area, and they seem to be well insulated. I had a friend who used one for the bandswitch of his 4-1000A amp, which operated at over 4 kV. Every few years he got s; /archives//html/Amps/2013-09/msg00090.html (9,978 bytes)
122. Re: [Amps] Workshop Danger (score: 1): Author: Vic K2VCO <k2vco.vic@gmail.com>; Date: Fri, 13 Sep 2013 08:36:22 -0700; I have a drill press with speeds ranging from fast to escape velocity. I've given up on hole saws, and admit that I've gone back to drilling several 3/8" holes around the periphery, joining them with; /archives//html/Amps/2013-09/msg00122.html (10,158 bytes)
123. Re: [Amps] Rectifier equilization? (score: 1): Author: Vic K2VCO <k2vco.vic@gmail.com>; Date: Fri, 13 Sep 2013 09:54:16 -0700; The resistors are definitely not needed. I used capacitors in my recent project in order to eliminate switching noise which might appear in my receiver -- I don't know if this was needed, since I did; /archives//html/Amps/2013-09/msg00128.html (7,781 bytes)
124. Re: [Amps] Rectifier equilization? (score: 1): Author: Vic K2VCO <k2vco.vic@gmail.com>; Date: Sat, 14 Sep 2013 20:31:13 -0700; Absolutely correct! I learned this the hard way when I accidentally shorted the screen to ground in my 813 amplifier. Poof, no more screen meter, despite back-to-back diodes. also use the 6A10 as a s; /archives//html/Amps/2013-09/msg00178.html (9,567 bytes)
125. Re: [Amps] LF oscillation caused by defective plate choke? (score: 1): Author: Vic K2VCO <k2vco.vic@gmail.com>; Date: Wed, 09 Oct 2013 08:51:33 -0700; I am using a 25 ohm 50w wirewound glitch resistor immediately after the plate choke. I have 0.01 uf 6 kV discs in parallel with 0.001's on both sides of the resistor and at the HV connector. I presum; /archives//html/Amps/2013-10/msg00155.html (9,814 bytes)
126. Re: [Amps] high voltage fuses (score: 1): Author: Vic K2VCO <k2vco.vic@gmail.com>; Date: Thu, 10 Oct 2013 09:13:53 -0700; We used to call this the 'voltmeter method' of measuring current. You put a resistor in series with a milliammeter to convert it into a voltmeter -- and then use it to measure the voltage drop across; /archives//html/Amps/2013-10/msg00186.html (10,852 bytes)
127. Re: [Amps] repair of older Command Tech VHF-2000 amp (score: 1): Author: Vic K2VCO <k2vco.vic@gmail.com>; Date: Tue, 15 Oct 2013 08:27:20 -0700; Answers to pure multiple-choice exams are easy to memorize. When I took amateur and commercial exams more than 50 years ago, schematics were required, as well as a number of mathematical computations; /archives//html/Amps/2013-10/msg00263.html (11,902 bytes)
128. Re: [Amps] Alpha 76PA to 6 Meters (score: 1): Author: Vic K2VCO <k2vco.vic@gmail.com>; Date: Wed, 16 Oct 2013 09:37:49 -0700; That's what they are quoting to do the job, or for the wafer alone? Anyone have any info/links to a conversion article? Alpha won't budge on $300 for a bandswitch wafer replacement. TNX Rick, N6PE ==; /archives//html/Amps/2013-10/msg00291.html (7,217 bytes)
129. Re: [Amps] 200-ohm tank and "un-un" in HF amp design? (score: 1): Author: Vic K2VCO <k2vco.vic@gmail.com>; Date: Sun, 20 Oct 2013 21:56:42 -0700; Don't believe the 1.8. I found that this is far from the correct value for the 4CX1000A. Maybe it's closer for triodes like 8877s, maybe not. See <http://www.granta.g4axx.com/Linear_design_notes.php3; /archives//html/Amps/2013-10/msg00369.html (10,872 bytes)
130. Re: [Amps] 200-ohm tank and "un-un" in HF amp design? (score: 1): Author: Vic K2VCO <k2vco.vic@gmail.com>; Date: Mon, 21 Oct 2013 08:12:04 -0700; Right. I said maybe and maybe not. I also included a link to the constant-current curve for the 8877 so he can find out for sure. 73 Jim W7RY I found that this is far from the correct value for the 4; /archives//html/Amps/2013-10/msg00378.html (12,606 bytes)
131. Re: [Amps] 200-ohm tank and "un-un" in HF amp design? (score: 1): Author: Vic K2VCO <k2vco.vic@gmail.com>; Date: Mon, 21 Oct 2013 13:13:33 -0700; Note that this lengthens the VHF 'parasitic tank circuit' between the plate, the frame of the tune capacitor, and the cathode. So it can cause instability. This design uses 3uH of "lead" inductance f; /archives//html/Amps/2013-10/msg00385.html (11,287 bytes)
132. [Amps] Screen regulation (score: 1): Author: Vic K2VCO <k2vco.vic@gmail.com>; Date: Tue, 22 Oct 2013 15:18:27 -0700; For reasons that I won't go into, I want to put a 22 ohm resistor between a regulated supply and the screen of a 4CX1000A. This would upset the regulation to the tune of 0.77 volts when the screen cu; /archives//html/Amps/2013-10/msg00406.html (6,741 bytes)
133. Re: [Amps] HV fuses (score: 1): Author: Vic K2VCO <k2vco.vic@gmail.com>; Date: Fri, 25 Oct 2013 08:39:27 -0700; Also I would add that if the tube is a tetrode or pentode, you must have a screen current trip circuit as well. Otherwise, if the fuse blows for any reason you will destroy the screen. On 10/25/2013; /archives//html/Amps/2013-10/msg00428.html (10,882 bytes)
134. [Amps] 4CX1000A project (score: 1): Author: Vic K2VCO <k2vco.vic@gmail.com>; Date: Sun, 27 Oct 2013 20:03:22 -0700; I've added a few more photos to my 4CX1000A amplifier page at <http://www.qsl.net/k2vco/4CX1000A/K2VCO%204CX1000A%20Amplifier.html> I finished the wiring as well as testing and adjusting the Tetrode; /archives//html/Amps/2013-10/msg00431.html (7,398 bytes)
135. Re: [Amps] 4CX1000A project (score: 1): Author: Vic K2VCO <k2vco.vic@gmail.com>; Date: Mon, 28 Oct 2013 07:15:06 -0700; I know. One thing I've done is included two ground conductors in the control cable that goes to the amplifier. So if someone were to disconnect the HV cable while the supply was energized, it would s; /archives//html/Amps/2013-10/msg00434.html (9,875 bytes)
136. Re: [Amps] 4CX1000A project (score: 1): Author: Vic K2VCO <k2vco.vic@gmail.com>; Date: Mon, 28 Oct 2013 11:31:20 -0700; I bought the blower on ebay. It is Japanese and the model number is B353-3. It is a 200v blower, so I used a tap on one of the transformer primaries. Unfortunately, I forgot the name of the manufactu; /archives//html/Amps/2013-10/msg00438.html (11,353 bytes)
137. [Amps] Small mystery (score: 1): Author: Vic K2VCO <k2vco.vic@gmail.com>; Date: Tue, 29 Oct 2013 10:22:10 -0700; I'm starting to test my 4CX1000A amplifier and I have noticed something that I don't understand. The amplifier has three operating states, which I call READY, ENABLED and TRANSMIT. In READY, HV = 340; /archives//html/Amps/2013-10/msg00444.html (8,529 bytes)
138. Re: [Amps] Small mystery (score: 1): Author: Vic K2VCO <k2vco.vic@gmail.com>; Date: Tue, 29 Oct 2013 12:02:00 -0700; The voltage can be varied by changing a resistor, up to at least -120v if I wanted to. There should be at least 8 ms between the signal to go into TRANSMIT and when the RF drive appears, and the inpu; /archives//html/Amps/2013-10/msg00448.html (11,154 bytes)
139. Re: [Amps] Small mystery (score: 1): Author: Vic K2VCO <k2vco.vic@gmail.com>; Date: Tue, 29 Oct 2013 18:46:59 -0700; Thanks to everyone for their help. The consensus was that the cutoff bias needs to be higher, and this is indeed the case. -115V completely cuts off the tube. WB2WIK --Original Message-- From: Amps [; /archives//html/Amps/2013-10/msg00449.html (9,629 bytes)
140. Re: [Amps] Large Variac controlling HV power supply (score: 1): Author: Vic K2VCO <k2vco.vic@gmail.com>; Date: Thu, 31 Oct 2013 08:30:38 -0700; If anyone is interested, I have a 5 kVA variac (input 120 - 0 - 230, output 0 - 250) sitting here that is free if someone wants to pick it up in Fresno. If I have to ship it, I will sell it for $75 p; /archives//html/Amps/2013-10/msg00468.html (9,664 bytes)

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