[Lowfer] A power supply head scratcher

Sun Apr 18 06:46:50 EDT 2010

Andy

One last thing to try if you haven't already...

Put a load resistor on each of the power supplies individually rather than across the combination. 
If that doesn't work, open them up and scavenge the power transformers for use with your regulator 
board.

Jay

----- Original Message ----- 
From: "Andy - KU4XR" <ku4xr at yahoo.com>
To: " European & UK) and MedFer bandsDiscussion of the Lowfer (US" <lowfer at mailman.qth.net>; 
"Part-15 Yahoo" <part15 at yahoogroups.com>
Sent: Saturday, April 17, 2010 11:32 PM
Subject: Re: [Lowfer] A power supply head scratcher

Hi Gentlemen:

As usual, a wrong choice of words on my part. I tied the positve wire
of one wart to the negative wire of the other one. The remaining
positive , and negative wires went to the circuit. At this point, I am
just about ready to sling these thing as far into the pond next door
as I can throw them. In all my years. I have never had a power supply
to do such crazy things. BUT !!! I must state that I have never tried
to use these stinkin little SMPS wall warts either. Always used analog
supplies before. But you don't find 30+ volts DC in an off the shelf
store bought power supply. The best thing I could do now is to just
build myself a good analog supply with a 24 volt transformer. That
should approach the 30 volt output when filtered, and then run it into
my adjustable regulator board to get the 25 volts I need, or very close
to it at least.

To note for the record:  Thanks to everyone for the tips offered.
I have tried all of them. .1 caps everywhere I could fit one, reverse
biased diodes, load resistors across the output. even tried the
paralled diode, resistor, capacitor trick. Nothing will stop the spikes
from killing the beacon.  *** There is a better than not chance that the
wall wart is bad. Could be why I found it in a junk box of parts at the
local flea market.

Andy - KU4XR - EM75xr - Friendsville, TN. USA
LOWfer Beacon " XR " @ 185.29875 KHz ( QRSS-60 )
Coordinates:  N:  35º 43' 54" - W:  84º 3' 16"
http://www.myspace.com/beaconxr
http://webpages.charter.net/ku4xr/

--- On Sat, 4/17/10, Jordan <outposter30 at shaw.ca> wrote:

> From: Jordan <outposter30 at shaw.ca>
> Subject: Re: [Lowfer] A power supply head scratcher
> To: "Discussion of the Lowfer (US, European, & UK) and MedFer bands" <lowfer at mailman.qth.net>
> Date: Saturday, April 17, 2010, 8:47 PM
> You're going to start a fire....
>
>
> ----- Original Message ----- 
> From: "Bill Ashlock" <ashlockw at hotmail.com>
> To: <lowfer at mailman.qth.net>
> Sent: Saturday, April 17, 2010 5:27 PM
> Subject: Re: [Lowfer] A power supply head scratcher
>
>
>
> "I simply connected them 10 volt positive open, and the
> negative
>  connected to the 24 volt positive, with the negative
> open."
>
> Hi Andy,
>
> Am I correct in my thinking that you have not connected
> anything to one of
> the two output wires of each wallwart? If so, I don't
> understand why this
> works at all unless there is some kind of sneak path to the
> neutral line in
> each power supply. Why not connect them in series as though
> they are
> batteries? These wallwarts have a power transformer that
> should isolate the
> DC output from their AC power inputs and this DC should
> float relative to
> anything else.
>
> Bill
>
> > Date: Fri, 16 Apr 2010 20:38:58 -0700
> > From: ku4xr at yahoo.com
> > To: lowfer at mailman.qth.net;
> part15 at yahoogroups.com
> > Subject: [Lowfer] A power supply head scratcher
> >
> > First, Thanks for all the responses to the antenna
> insulator question.
> > J.B. had the one i'd never of thought up, The broken
> pole vault pole.
> >
> > I do have a head scratcher here. To get around 35
> volts DC, I have
> > connected 2 wallwarts in series. One is a 10 volt, and
> the other,
> > a 24 volt. Connected together I have 37 volts DC. ***
> This is the first
> > time I have ever tried this method before, so I have
> no previous
> > experience to go by. I simply connected them 10 volt
> positive open, and
> > the negative connected to the 24 volt positive, with
> the negative open.
> > The problem I'm having is that everytime something in
> the house turns
> > OFF, it kicks off the beacon....hmmmm. AC goes off,
> and so does the
> > beacon, fan in the room goes off, beacon does too.
> connect the HF ant.
> > to the radio and it kicks the beacon off. I have
> filtered the hound out
> > of it. But can't stop this problem. It seems to be
> coming in on the
> > ground line. These 2 wallwarts were 2 pronged plugs,
> and would not work
> > the circuit until I connected a 3 prong plug with the
> ground wire going
> > to the DC negative wire. The warts are SMPS. Even
> though I have the
> > voltage I want, something is amiss. It is getting
> spiked somehow.
> > Has anyone tried this before, and had a similar
> experience ?? If so,
> > were you able to fix it, and how did you do it ?? I
> may have something
> > wired the wrong way, or maybe missing a capacitor
> where one should be.
> > I don't have a schematic for a circuit like this, and
> can't find one
> > on the net. I'm wondering if I have a floating ground
> issue between the
> > 2 wallwarts.
> > Any input will be appreciated, and thanks for your
> time.
> >
> > 73 everyone :::
> >
> >
> > Andy - KU4XR - EM75xr - Friendsville, TN. USA
> > LOWfer Beacon " XR " @ 185.29875 KHz ( QRSS-60 )
> > Coordinates: N: 35º 43' 54" - W:
> 84º 3' 16"
> > http://www.myspace.com/beaconxr
> > http://webpages.charter.net/ku4xr/
> >
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