[ARC5] Power Supplies for Your ARC-5

[David Stinson]

I started out with two 12 volt, 35 amp Astron power supplies
in series.  They would not start a DM-33- one or both would
go into overcurrent shutdown every time.
Dave S.

"Paul H. Anderson" wrote:
> 
> Hi folks,
> 
> I may not fully understand the power supply situation, but my experience
> suggests that the Lambda 9A supply I have is more than enough for these
> small dynos and motors.  They have output voltage sensing feedback on
> them, so the current is clamped at 9 amps (in my case), by dropping
> voltage as needed, but the voltage does not drop to zero except in total
> failure.
> 
> The dyno starts with strong authority - no slow windup.  I have another
> lab power supply that puts out 9 amps, and when running dynos on it, the
> starting current appeared to be 4-5 amps.  I know that the resolution of
> my observation isn't accounting for the true peak value (the one measured
> in milliseconds), but a good clamping circuit should have no problem with
> that.
> 
> Let me get the model numbers tonight.  I have several, and I'm confident
> that any of them have the guts to do a DM-33 dyno.  One that may not is a
> lab supply that only put out 1amp (tried it on my R-391 motor, and it
> didn't have enough guts to do it).  The DM-33 is really a small, small
> electrical motor, and a few amps "should" be enough.  No need for more
> than 10 amps, at any rate.
> 
> The supplies listed below are a lot more expensive than is needed to run
> one dyno and the receiver.  The issue of switcher noise may still be a
> problem, however.
> 
> I'm wondering if power supply design and manufacturer varies enough so
> that one PS at 9amps might work fine, whereas another "crowbars" to zero
> volts?  The lambda designs that I'm familiar with just don't do this.
> 
> I tried to get some idea of RF noise on the power supplies by looking at
> it with my scope while the supply is under load, but what I'm able to tell
> with my experience and tek-465 scope doesn't allow me to see any
> apparently significant levels of 60 or 120C or RF noise.  I welcome
> pointers to information about how properly test this.
> 
> I think I have a smaller 3AMP 28V lambda - I believe it will have no
> problem running my ARC-5 with DM-33 dyno - I'll see if I can try it
> tonight and report back on that, too.
> 
> But, one has to remember that these radios were operated in a bomber, and
> I strongly doubt that they had squeaky clean power supplies back then.
> The dyno itself is probably a big contributer of noise, at least more so
> than the power supplies I use.
> 
> Paul
> 
> On Tue, 15 Jan 2002, David Stinson wrote:
> 
> > The current ratings written on the dynamotors
> > are the running currents.  The starting surge current
> > will be much higher.  I don't remember off hand what
> > the starting current for a DM-33 or DY-8 is, but I think
> > it's around 25 amps.
> > Most of these supplies have protection against surges.
> > If you use a lower-current supply,
> > most will "crowbar" and go to zero until reset.
> > A 10-12 amp supply will run your receivers OK,
> > but it won't start a DY-8 or DM-33.
> >
> > You can overcome this by using some large capacitors
> > in a bank to provide the surge current, while the power supply
> > provides the running current.  24 volts in batteries will
> > also work.  Old IBM printers and antique
> > main frame computer equipment contain lots of these big
> > caps, where they served the same function.
> >
> > If you use a switcher, you'll likely need to build an
> > RF bypassed enclosure.  They're designed for lasers and
> > RFI isn't usually an issue for those applications.
> >
> > Some 24-28 volt supplies at higher currents
> > on the Bay right now:
> >
> > 1322466303
> > 1690276274
> > 1062389767
> > 1688821631 (good deal on this one but will need shielding).
> >
> > 73 Dave Stinson AB5S
> 
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