HP-23 upgrade

[Dick KF4NS]

I am getting ready to refurbish my 1970 HP-23A which has not been
touched since I built it but there is hum now and besides it is long
overdue for new caps.

I have the article by Mike Bryce WB8VGE which was in OCT '03 QST and I
see that he made several changes. I am using it with Heath gear only
so will forego the regulator. I am not challenging Mike's knowledge
and abilities but rather, I need an explanation of a couple of the
changes. I understand that Mike is a bit disabled now due to an
accident that put his hands out of commission or I would ask him. Hope
he recovers real soon.

(parts ID same as original schematic)
I already have four new Xicon 100uf 450V caps so will use them for
C1-C2 in HV ckt unless a higher value is a better idea.
Why the position swap of C5/R5 and increasing C5 to 220uf in the LV
circuit? Do I really need to change C3-C4 to 220uf?
As far the bleeder resistors go, what is the reason for reducing
bleeder current?
All diodes will be changed to 1N4007's.
C6-C7 will be same value; new 20mfd 150V Sprague ATOMs.

I will test all the resistors but wonder about the need  to increase
them to 3W. None look like they have been overheated but after testing
them, I may change my mind.

I already added an ICL in the hot AC lead and a new 3-wire power cord.
Not sure whether to replace the circuit breaker with a 2A slow blow
fuse. Any advice?

Any enlightenment would be appreciated. Thanks and 73, Dick KF4NS
St Petersburg, FL 33714 USA
Keep The Glow!

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