[time-nuts] HP5370 power supply measurements

Charles Steinmetz csteinmetz at yandex.com
Wed Jul 13 03:11:57 EDT 2016

Poul-Henning wrote:

> So I've been playing around with KICAD and come up with a design
> with three Traco TEN40WIR DC/DC converters (2x2411 + 2423) running
> off the +/- 10V rails, and I'm seriously tempted to try order a
> PCB just to try it out...

Are the Traco converter modules cheaper where you are than here in the 
US?  It looks like the three converters would cost more than $360 here 
-- almost double what I paid for my most expensive 5370B.  I recognize 
that you get a fair amount in the package, but the regulation and noise 
specs -- while OK -- are certainly not stellar.

An external fan blowing on the heatsink keeps my 5370s nice and cool, 
for about $10 each.  The ones I use are 120v, clamp-on types sold for 
making a breeze at a workstation, and are extremely quiet.  The 
heatsinks run barely warm to the touch.

Reducing line consumption by 50w would save about $3 per counter per 
month here, assuming 24/7 usage.  Break-even on the cost of the 
converters would therefore be ten years, *if the counters were operated 
24/7/365*.  I sometimes take data for a few months straight, but very, 
very far from 24/7/365 on average.  So for me, break-even would be more 
like 50 years.  Even if you pay a lot more for electricity than we do 
here, it's still a very long time before you break even.

Speaking of fan noise -- you can't really get away with replacing the 
internal fan with one that moves less air, so it is hard to find a 
replacement that generates significantly less noise.  If you find one, 
please share the make and model -- all 5370 owners would love to know.

Best regards,


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