POWER SUPPLY FOLLOW UP

Well, the HV power supply seems to be humming along nicely.  The meter on the control head displays 2500 VDC which is probably about right considering my line voltage in the shack (248 VAC).  As promised, I measured all the resistors that were removed from the supply and noted their values.  I also noted their specified range based on the five percent tolerance value.  As expected, not a one was in spec.  I’m not sure that this really makes much difference as the power supply isn’t exactly a calibrated circuit, but it would be silly not to replace them while refurbing the supply.  They’re inexpensive and easy to replace.  I substituted metal film resistors of the same value and power rating rather than the original carbon composition.

I haven’t had a single issue at all with breakers tripping on the amp or sub panel since making the repairs.  I’ll conclude that it was definitely a faulty filter cap (or maybe several).   It uses six 240 uF 450V computer grade electrolytics in series for a total of 40 uF DC filtering goodness.  I don’t have a way to test them at this time to determine their values.   Actually, I don’t even have them anymore.  The neighbor kid (Jacob KC9ZYV) wanted them (and also the caps from the Amp Supply LK-500 NT power supply I refurbed last year).  He mentioned something about a rail gun…future mad scientist at work!

I recorded the values for everyone on a pad of genuine Purdue green engineering graph paper.  I still have nearly a full pad of this stuff after nearly 20 years.  I wasn’t an engineering student!  I hope you all find the info interesting.  The next order of business for the amp is to synch the DC drive system with the Tune and Load air variable caps in the RF deck.  Then I can calibrate them all for roughly every 100 KHz of each band and let the amp auto tune itself!

Check out how far some of the resistor values have changed.

Check out how far some of the resistor values have changed.

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Categories: Activities, Amateur Radio, Projects | Tags: , , , , , | Leave a comment

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