Kx3 supply

[Jim Miller]

Consider this one:

http://www.gammaresearch.net/hps-1a.html

Jim ab3cv
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[Jim Low man]

What price quiet?

Man - $199!  I think I'll give the one that Eric and Wayne recommended a
try.

72/73 de Jim - AD6CW


On 4/5/2012 8:41 PM, Jim Miller wrote:
> Consider this one:
>
> http://www.gammaresearch.net/hps-1a.html
>
> Jim ab3cv
>

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[erehm]

Based on this QST 2007 review, it was a noisy switching supply at one time.  I understand the manufacturer made a "capacitor type" change, circa 10/2008, but personally I would like to see a QST retest of this supply (or similar spectrum analyzer plots) before purchasing this supply.

http://www.rv3apm.com/qstff.pdf

/eric, kj7ae

[Dave Van Wallaghen]

Hey Eric,

Where did you find the info on the change? (Google was not my friend). I
purchased mine in April of 2008. I would be interested to see if I could
make the change myself.

73,
Dave W8FGU


On 4/7/2012 10:40 AM, erehm wrote:
> Based on this QST 2007 review, it was a noisy switching supply at one time.
> I understand the manufacturer made a "capacitor type" change, circa 10/2008,
> but personally I would like to see a QST retest of this supply (or similar
> spectrum analyzer plots) before purchasing this supply.
>
> http://www.rv3apm.com/qstff.pdf
>
> /eric, kj7ae

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[Jim Brown-10]

On 4/7/2012 10:24 AM, Dave Van Wallaghen wrote:
> I would be interested to see if I could
> make the change myself.

I cleaned up a couple of cheap switchers that I  bought at a hamfest by
adding a line-voltage rated capacitor across the AC line, an RF cap
across the DC output, and serious multi-turn ferrite chokes to both the
AC line and the DC output.  I also added a couple of clamp-on cores to
kill the stuff on 2M.

Total cost of my clean-up was about $10 (I bought the cores as part of a
group purchase for $4 each), and the power supplies cost me $10 each.  
Doing it right when they built them would probably have added less than
a buck to the cost, and most of doing it right is circuit layout, not
components.  See my RFI tutorial for guidelines on winding the chokes,
and also for detailed info about line-voltage rated capacitors.  Hint --
they must be rated for the surges of several kV that often occur on the
AC line.

73, Jim K9YC
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[Dave Van Wallaghen]

Thanks Jim. I always have an updated version of your tutorial on my laptop!

Eric alluded to some type of internal change and that is what I was
hoping to get info on. But I will certainly try your suggestions (most
likely either way) if I can't find the info or it turns out to be
unfeasible with my version of that supply.

I have not really had too many problems with RF noise with this unit. I
use it when I'm portable and have noticed if I use a ladder line fed
doublet, that if the ladder line is in close proximity I will pick up
some noise (sweeping noise). If I use a small length of coax to a balun
with the ladder line (pushing the ladder line further away), I don't
notice the noise as much.

Anyway, thanks for the info as always.

73,
Dave W8FGU


On 4/7/2012 1:42 PM, Jim Brown wrote:

> On 4/7/2012 10:24 AM, Dave Van Wallaghen wrote:
>> I would be interested to see if I could
>> make the change myself.
>
> I cleaned up a couple of cheap switchers that I  bought at a hamfest by
> adding a line-voltage rated capacitor across the AC line, an RF cap
> across the DC output, and serious multi-turn ferrite chokes to both the
> AC line and the DC output.  I also added a couple of clamp-on cores to
> kill the stuff on 2M.
>
> Total cost of my clean-up was about $10 (I bought the cores as part of a
> group purchase for $4 each), and the power supplies cost me $10 each.
> Doing it right when they built them would probably have added less than
> a buck to the cost, and most of doing it right is circuit layout, not
> components.  See my RFI tutorial for guidelines on winding the chokes,
> and also for detailed info about line-voltage rated capacitors.  Hint --
> they must be rated for the surges of several kV that often occur on the
> AC line.
>
> 73, Jim K9YC

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[erehm]

"Capacitor type change" was mentioned on the KX3 Yahoo! Group:

http://www.minute-man.com/acatalog/4_Conductor_3_5mm_Plugs_and_Jacks.html

/eric, kj7ae

[erehm]

Ooops...freak in Android paste. correct URL:

http://groups.yahoo.com/group/KX3/message/3636