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Author Topic: Heathkit PS-23 power supply diodes  (Read 4439 times)
KB1NXE
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Posts: 309




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« Reply #15 on: October 19, 2010, 07:44:31 AM »

Heathkit usually spec'd their components to fill the requirement, but would hedge their specifications on the side of cost savings.  Their engineers usually lost out to the bean counters.  So, if you take a look using Ohms Law on the bleeder resistors you will find on the high end of the regulation it might exceed the 2 watts the resistor is rated for.  This is why they tend to burn out.  The Kit uses 3 watts to avoid this in the future.  FWIW, the kit is a good choice as it includes all the parts and they are modern parts.  Can you find them all for cheaper?  Certainly.  But consider what gas cost going there and the time is worth searching for the parts or if online, the shipping, etc.  You pay for convenience.

Also, no one is challenging your knowledge of electronic theory (once you let them know your level of training and experience).  We usually work in a vacuum of what the OP's knowledge and experiences are.  Not fair, I agree, but human nature.  Take it worth a grain of salt.



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KB3HG
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Posts: 404




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« Reply #16 on: October 19, 2010, 07:51:14 AM »

 1/2 CV^2 rig a bell, where V is voltage
Tubes, is that was those things that glow are in my Heath kits? That warm glow that shows through the ventilation holes.  Now that I have your attention, High voltage, yes it bites, use extreme caution working on that supply, since you said you are comfortable with lower voltages. One hand behind your back ect. Plain and simple. You have the diode information,generally bigger is better. Ever hear the adage when you were in class, "If some is good more is better?" works for bypass capacitors,  bleeder resistors (wattage wise) also. Arbitrarily changing parts is in your best interest. (cost wise) another thing I don't remember a specific date  resistors that were coated or sprayed with Pcbs were stopped being produced. Wash up after handling old components. Some say that the circuit breakers went on that supply also,  make sure the resistors that are across the caps are good.  Good practice said after power was removed that the high voltage should be less than 60V in less than 60 seconds. A Bad bleeder will not discharge the high voltage caps.

What ever you do don't get upset with the others about the theory, a little knowledge is a dangerous thing. Really, they are looking out for you. At these higher voltages you get to make very few mistakes, and what ever you do make sure your meter can take over a thousand volt spike or better yet,use a voltage divider.when playing with supplies with out the supply loaded down and parts not connected ect you can have a voltage doubler real quick. Heed their advice, Jim had the navy link. Get an older handbook. Be safe and enjoy the adventure, it is a hobby after all.

Tom Kb3hg
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N4NYY
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Posts: 4749




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« Reply #17 on: October 19, 2010, 08:14:04 AM »

Tom, I understand. I guess it is my own fault as I let it slip. After tech school, I was working on a bench withyour typical test equipment (non-RF stuff) and refurbishing badly beaten up data loggers, which is why I have good abilities at disassembling and restoring.  However, I had switched jobs back in 1994, and that was the last of the bench and component work, up until I got back into about 3 year ago. I got my ticket in 2005, but I was dormant because or the birth of my daughter. Only in the last 2-3 years have I gove back into head first. I refresher will certainly be warranted.
« Last Edit: October 19, 2010, 08:59:54 AM by Vinnie Sallustio » Logged
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