I have two Astron power supplies; a VS-35M & a RS-35M. The RS-35M has
stopped working & I have to track down that issue. While I'm in
there, are there any known mods I should do to either of these?
Sounds like I should remove the paint under the lug and attach the
green wire properly to the chassis.
Anything else that's suggested?
An aside, the lamps in these meters are terrible, both of these
supplies are fairly new and all four of the meter lamps are dead and
absolute buggers to get at. Several calls to the company were met
with indifference and no replacement lamps.
If there's known mods, I'm always keen on upgrading my station.
73,
Gary
KA1J
> On Tue,1/27/2015 4:08 PM, Tom W8JI wrote:
> > The flaw in this system is that differential voltages between current
> > carrying wires are not measured, and anything on the safety ground
> > isn't measured. Noise voltage is only measured from individual
> > current carrying conductors to ground, and the safety ground is
> > grounded and not measured.
>
> Exactly right, Tom. A common design/manufacturing defect is that the
> green wire fails to make contact with the shielding enclosure, but
> instead goes to common on a circuit board, which may or may not ever
> find the chassis. This defect, which is the power system equivalent of a
> Pin One Problem, puts noise on the green wire. You may remember that we
> corresponded several years ago about Astron power supplies, in which a
> very common defect is that the green wire is soldered to the mounting
> lug of a terminal strip, which is insulated from the chassis by paint.
> The same mounting lug is the point where V- is bonded, so it never finds
> the chassis either. AND, wiring for both V- and the green wire act as
> antennas for both TX and RX.
>
> I have long suspected that similar defects are at least partially
> responsible for noise conducted onto coax and AC lines from consumer
> products of all sorts.
>
> 73, Jim K9YC
>
>
> _________________
> Topband Reflector Archives - http://www.contesting.com/_topband
>
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