Paul, K2ORC
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« Reply #25 on: April 04, 2005, 01:21:01 PM » |
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Okay. I get it now. Funny because I'd built a screen voltage regulator for a homebrew transmitter and the circuit, although for lower voltage, was considerably less complex than the Measures circuit. It appears the LM723 added quite a bit to the parts count as you say, John. Thanks for the clarification.
Paul
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Go Duke![/b]
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WA1GFZ
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« Reply #26 on: April 04, 2005, 01:58:37 PM » |
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Wow that is a lot of parts!
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kc2ifr
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« Reply #27 on: April 04, 2005, 02:16:11 PM » |
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Im gonna try and post the schezmatics of the tetrode boards I am using for the screen and bias supplys.....but they are BIG.........Number 1
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kc2ifr
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« Reply #28 on: April 04, 2005, 02:17:13 PM » |
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Number 2
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kc2ifr
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« Reply #29 on: April 04, 2005, 02:18:03 PM » |
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And finally number3....
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kc2ifr
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« Reply #30 on: April 04, 2005, 02:19:32 PM » |
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Well......there they are...all three. What do u guys think......... BTW......I already paid for em....
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w3jn
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« Reply #31 on: April 04, 2005, 02:46:34 PM » |
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Lotsa protection there - if there's one criticism I could make it's lack of a crowbar for the screen. Easy to make - see the crowbar portion on the circuit Tom Vu posted.
73 John
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FCC: "The record is devoid of a demonstrated nexus between Morse code proficiency and on-the-air conduct."
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WA1GFZ
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« Reply #32 on: April 04, 2005, 03:05:14 PM » |
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When it comes to high voltage linear regulators KISS is the way I would go. The power is quite low so I would do Zener shunt myself to limit energy.
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wavebourn
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« Reply #33 on: April 04, 2005, 07:07:18 PM » |
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When it comes to high voltage linear regulators KISS is the way I would go. Like this one?
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W2VW
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« Reply #34 on: April 04, 2005, 10:44:20 PM » |
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One thing which you want to check after a failure involving the screen supply is the screen bypass capacitor(s). I imagine yours is built into the socket. You can reject it with an Ohmmeter test but also apply some current limited DC Voltage to it maybe 20% over what you plan to use in service. Check to make sure that the dielectric has not been punctured by excessive Voltage.
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WA1GFZ
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« Reply #35 on: April 05, 2005, 08:59:06 AM » |
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Tolly is getting closer. Just put an emitter resistor on Q2 and eliminate all the negative stuff. A series pass regulator would require a load resistor to deal with negative screen current while a shunt regulator would handle that also. The screen rating is so low with 4CX1000 / 1500 you don't want a big power supply source that could deposit the screen on the plate making it a triode. Why have a 100 watt power supply for a what 5 watt grid.
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kc2ifr
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« Reply #36 on: April 05, 2005, 04:39:29 PM » |
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Lots of good stuff from u guys.......tnx. Well I already purchased the "tetrode boards" so I might as well use them. The seller usually sold all the parts as well as the boards but for some reason the parts wont be available from him for about 3 months so I have to get them myself. Most stuff is no problem to get from my local supplier except for a few things that I will get from mail order. As was pointed out...this toob draws negitive screen current so that has to be taken into consideration in the design. If anyone is interested.....the complete manual for the boards is available from the website. Thanks again for the help and advice....Ill keep ya all posted. Bill
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wavebourn
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« Reply #37 on: April 09, 2005, 03:32:56 PM » |
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Frank, if to eliminate negative stuff you'll loose soft start. But if it is not a problem, instead of resistor in emitter of Q2 you must add a zener, to get regulated voltage.
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