[Elecraft] Elecraft Digest, Vol 89, Issue 15

[David Dunn]

Re:] Switch mode PSU

I just read the comments and reply in the message below:
I have both those PSU, the Sec 1223  is by far the oldest one. It has
several" birdies"   best described as rather Raucous Crows, which get worse
as the frequency goes lower. 160m is pretty poor.   I added several devices
in attempts to quieten same, which was achieved to some degree.  It is
acceptable on all but 160m,   where it appears in about 3 places across the
band, (not always the same places)  The Waters and Stanton  Power Mite is
cheaper device and does much the same  although trips off when the full 20
amps is drawn quite often. It has similar noises on several bands, which I
can live with but is about the same as the other on 160. I have not
attempted to add filters due to the limited success of the other. There is
little doubt the "proper" transformer PSU's I have are best   but where
weight is concerned the switch modes units are light and neat for the cost.
-  Ideal I guess for the VHF folk

  73   David G3SCD / VK3DBD
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Message-ID: <C27A8EE8-BD45-4069-A787-D8BBB9D59B3F at Alphadene.co.uk>


Iain, I use a Power Mite from Walters & Stanton when not in the shack - is
very quiet, both physically and RF wise
73 de M0XDF, K3 #174, P3 #108, KX3 #???

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On 10 Sep 2011, at 22:58, Iain Haywood wrote:

> Hi,
>
> Has anyone had any bad experiences using a K3 and a switch mode PSU?.
> The SEC-1223 looks great aware some can cause problems..
> They say 'Totally noise free', that's some claim..