-----Original Message-----
From: W2HX <w2hx at w2hx.com>
Sent: 27 January 2022 00:11
To: rob at jarratt.me.uk; Rob Jarratt <robert.jarratt at ntlworld.com>; General
Discussion: On-Topic and Off-Topic Posts <cctalk at classiccmp.org>
Subject: RE: Testing H745 Regulators
Any chance you have a second supply you can parallel with the one you're
using? Some bench supplies are dual supplies and have a parallel mode so
you can benefit from both sides of the supply and they can track the same
voltage. Or just put two supplies in parallel with the same voltage set on
both
It is already a twin PSU, I am using one half to power the AC input and the
other half to power the +15V input.
I do have a separate bench PSU I could use for the +15V and twin up the
actual twin PSU, so I might try that next.
> 73 Eugene W2HX
> Subscribe to my Youtube Channel:
https://www.youtube.com/c/w2hx-
> channel/videos
> -----Original Message-----
> From: cctalk <cctalk-bounces at classiccmp.org> On Behalf Of Rob Jarratt via
> cctalk
> Sent: Wednesday, January 26, 2022 6:42 PM
> To: General Discussion: On-Topic and Off-Topic Posts
> <cctalk at classiccmp.org>
> Subject: Testing H745 Regulators
> I am trying to test a couple of H745
regulators with a DC bench PSU and I
am
> having some problems with testing them.
> My bench PSU is a twin unit so I can
supply the +15V required as well as
the
"AC" input using 20VDC from the other half
of the bench PSU. The problem
is
that I don't think the bench PSU can supply enough
startup current to
allow
> the regulator to run. It can only supply 5A max.
> I have seen with the H744s that if I put
too big a load on them, then they
> can't start because of the heavy startup current required. I can start
them
> with a lower load and then add load once the regulator is running without
> breaching the current limit of the PSU.
> With the H745s I have tried reducing the
load to see if I can get them to
start,
> but a 10R load appears to be too much and the regulators draw the full 5A
> without outputting -15V.
> I have two H745s, both exhibit the same
behaviour. I suppose they could
> both have the same fault, but I am inclined to think that perhaps they
need a
> higher startup current than I can supply. Can anyone confirm this?
> Thanks
> Rob
