[volt-nuts] Power Designs Precision Power Supplies

[Alan Hochhalter]

Ed,

I'm just a hobby user, and even that is a lot more part-time than I'd 
like.  Even in retirement I don't seem to have time...

Anyway, I have four Power Designs supplies purchased on eBay; two TP340 
triple output supplies, a 3650-S single output supply, and a 2005A 
precision supply.  (The latter purchased as much as anything because I 
thought the two dials on the front to select the voltage on the front 
were cool and it didn't cost much.)  I'm satisfied I got good value for 
my money.

I can't say much about their quality as far as noise/ripple/accuracy 
goes but they have worked fine for me as bench supplies.  One of these 
days maybe I'll check closer.....  I don't think I paid a whole lot for 
any of mine relative to some of the better known brands.  They're 
relatively heavy and don't seem to have been designed with compactness 
as first priority.

I had to replace two switches on one because they didn't work, but they 
were readily available toggle switches and one of those was a broken 
switch handle.  Not a big surprise when you don't try for pristine 
condition to save some money.  The 2005A has two pretty complex 
multi-position rotary switches with open contacts that didn't reliably 
give the same voltage on the same settings.  I used contact cleaner and 
got rid of at least most of that, but I don't know how accurate or 
repeatable it actually is since I didn't do any systematic testing.  If 
their other precision supplies use the same type of switches, I'd say 
that is a potential trouble area and probably would call for a good 
voltmeter to confirm you're really getting what you think you're getting 
on the output.  Other than that I haven't had to make any repairs.

They all seem to have pretty straight-forward construction so I'm 
thinking (maybe hoping is a better word) they shouldn't be too hard to 
maintain as long as something major like a transformer or those rotary 
switches doesn't go out.  I can see the 2005A has a "Reference Amplifier 
Oven" in a cylindrical can that is probably unobtainium, but mine have 
no processor modules, PLDs, displays or custom switch panels like a lot 
of the HP or Tektronix gear I've bought on eBay.  Not sure if that is 
because of their vintage or a function of being built by a smaller 
company that couldn't invest in lots of custom parts.

I'm not sure if I managed to get manuals for all of mine or not - I know 
I have some.  I moved a year ago and still have boxes of stuff I've 
never unpacked because I haven't got a workshop built yet.  Getting 
close finally!!!

Hope this helps.

Alan