[Heathkit] HP-23 Boards From HeathkitShop

[Bill Weinel]

>          Has anyone used the circuit board kit from
>    Heathkit Shop? If so, how is it?

Hi Ed,

I ordered two of the HP-23R boards from the Heathkit Shop (
http://www.theheathkitshop.com/hp23r.html ) a few months back to refurbish
my two HP-23 supplies here. I can heartily recommend them!

The boards are very high quality double sided boards with silk screening to
show where all the components are located. They perform as advertised and
add a few options as well. I ran across a couple of minor problems in the
parts procurement area and assembly documentation which might be worth
mentioning.

The boards come with very good step by step instructions, parts listing, and
diagrams. However, I found that the parts listing is somewhat dated. The
parts listing provided uses stock numbers from both Mouser and Digi-Key.
However, some of the part numbers are no longer available through Mouser. (I
think I remember the main filter caps being the item which Mouser no longer
carried... but you can get them through Newark online at www.newark.com )
If your worried about parts procurement, or just don't have the time to
spend tracking down parts... buy the complete kit.

I also remember that there was a small error in the diagram with resistor
part numbers. I seem to remember there was a resistor number in the screen
circuit schematic which was duplicated by another resistor used elsewhere in
the supply (I believe it was R11). I'm sure it was a typo, but should you
build one, be on the lookout for it so you don't get the wrong value
resistor in the wrong place.

On the plus side, the step by step assembly instructions are great. Almost
as good as the old heathkit manuals. Together with the pictures on the web
site, its a snap to assemble.

I still believe that for the money the kit is a very good value for anyone
with a HP-23 supply as the original FP twistloc filter caps are pure
unobtanium. The new HP-23R boards use CDE high temperature electrolytic cans
built for use in switching power supplies. I suspect those will probably
outlast us before they ever need changing again. The HP-23R also has a +300
vdc screen supply regulator circuit which can be added as an option. This is
great for those of you who use the supply with Collins gear.

At any rate... I hope this gives you a bit of insight as to my impressions
of the board. As usual, your mileage my vary...

73 Bill, W4WHW