[Elecraft] [K2] : Laptop UPS

[WILLIS COOKE]

You can't float the laptop power supply.  The neutral
pin of the plug is connected to the supply ground
point as well as the ground pin.  There is no ground
point on a plastic lap top for the station ground. 
The only way to float the computer is to unplug the
charger, which did work, but only until the battery
needs to be charged.  The better solution is to plug
the laptop into the same circuit as the radios.  Most
people do not have a choice like I do because houses
are usually wired room by room.  I don't understand
why this simple caveat is generating so many
arguments.  It is simple, worked for me and doesn't
apply to most people.

Cookie, K5EWJ

--- Brett Howard <brett at livecomputers.com> wrote:

> Or you could just easily float the laptop then you'd
> only have one
> chassis ground.
> 
> 
> On Sun, 2008-03-16 at 19:36 -0700, WILLIS COOKE
> wrote:
> 
> > Well I didn't plug it into my K3 with the
> transformer
> > isolation because my K3 is in its gestation period
> and
> > I am waiting for delivery.  But, I don't think
> that it
> > would have avoided the problem.  I was using
> > transformer isolation with a Rascal Interface. 
> The
> > hum came through the push to talk ground circuit. 
> One
> > of my friends had to replace the transistor PTT
> > interface with an Opto Isolator to eliminate his
> > ground loop problem.  I have a separate power feed
> for
> > my radio equipment that comes from a box at my
> meter
> > loop and quite different ground length from the
> house
> > wiring.  You need your computer fed from the same
> > power source as the radio equipment even if you
> have a
> > K3.
> > 
> > --- Brett Howard <brett at livecomputers.com> wrote:
> > 
> > > This is why we transformer isolate our audio. 
> > > If/when you get a K3
> > > you'll have this feature built right into the
> rig. 
> > > For me I just built
> > > a cable for the PSK/RTTY and what not and put
> > > transformers in a box in
> > > the middle of the cable.
> > > 
> > > 
> > > On Sun, 2008-03-16 at 05:57 -0700, WILLIS COOKE
> > > wrote:
> > > 
> > > > I don't know if it applies to your situation
> or
> > > not
> > > > Raymond, but I had a lot of hum on when I
> > > connected my
> > > > 110V Lap top to my TS-850 for PSK-31.  I had
> the
> > > > charger plugged into a house circuit and my
> radio
> > > > equipment plugged into a separate circuit for
> the
> > > > radio station.  When I moved the charger plug
> to
> > > the
> > > > radio circuit the hum went away.
> > > > 
> > > > --- Raymond METZGER <ray78crespus at orange.fr>
> > > wrote:
> > > > 
> > > > > Hi Elecrafters,
> > > > > 
> > > > >  
> > > > > 
> > > > > I am interested to know what solution can be
> > > used to
> > > > > avoid the noise
> > > > > generated by the 220 V AC (OEM) UPS of my
> recent
> > > > > Dell Latitude Laptop.
> > > > > 
> > > > > For the time being, I can only use the
> laptop
> > > with
> > > > > my K2/100 if the laptop
> > > > > is powered by its internal battery.
> > > > > 
> > > > >  
> > > > > 
> > > > > Raymond METZGER
> > > > > 
> > > > > F4FNT
> > > > > 
> > > > > K2 5,636 - K3 expected at month end (ordered
> 8
> > > > > September, "Katiegram"
> > > > > received last Friday)
> > > > > 
> > > > >
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> > > > 
> > > > Willis 'Cookie' Cooke 
> > > > K5EWJ
> > > >
> _______________________________________________
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> > 
> > Willis 'Cookie' Cooke 
> > K5EWJ
> 


Willis 'Cookie' Cooke 
K5EWJ