On 1/16/2012 4:34 PM, Dale Svetanoff wrote:
> Folks,
>
> As most of you know, the topic of RFI issues with switching (or "switch
> mode") power supplies pops up here quite frequently. I was delighted to see
> that the February issue of QST addresses the subject with lab tests on 4
> more such power sources. (See pages 56 thru 59 for all of the details.)
> Make certain that if you are interested in noise issues with switching power
> supplies, you read the entire article carefully. It is also worthwhile to
> track back and see the prior power supply test articles the League has
> published, and which are referenced in the footnotes.
I've used three makes of switchers without noise. One is the Tenma 40A
(variable voltage) lab supply, the Astron 30 amp (forgot the
designation), and the Icom PS30. The Astron failed after just a few
months. the fan failed after about a month. They promised to send me a
new fan which never turned up. Nor did they answer e-mails after that.
The Icom lasted many years and just failed to turn on one day. The
Tenma is a bit over 1 year old. it creates a bit of noise for about 1
second when first turned on. After that I can not hear it on any band.
It has a digital display with voltage continuously adjustable, but
readout is in one tenth volt septs. Voltage is constant from no load to
over 30 amps. (not even 0.1V change). The only thing I don't like about
the Tenma is the terminals are on the front panel, but it is after all a
lab supply and that's where you'd expect to find them. However one of
these days I'm going to add rear panel connectors. OTOH I won't
purchase a ham supply with the connectors on the front panel. They
just get in the way.
List price on the Tenma is pretty pricey at close to $300 but they
occasionally have some very good discounts. I think I paid a little
over 1/3rd the list price and it was certainly worth it.
BTW I have two Conventional Astrons. One is a 35A and the other is a 50A
although I changed out all the pass transistors in the 50A. The 35A is
about 5 to 7 years old and the 50A is at least 10 to 12 years old.
73
Roger (K8RI)
_______________________________________________
RFI mailing list
RFI@contesting.com
http://lists.contesting.com/mailman/listinfo/rfi
|