[hpsdr] spikes

[Erik Anderson]

Okay, I know this is an old email but it describes what I've been fighting
for a while now.  Part of the issue likely is that I feel a bit like I'm
forging my own path so I'm doing a lot more research online than action at
the radio for fear of not knowing what I'm doing (with radios).  Hopefully
I can get some input that would give me more of a focus as to what to look
for to resolve this.

I have been seeing this QRM:
(*) In the middle of my living room, connected to a poorly-constructed
random-wire antenna
(*) At the ACS building half an hour north of here, connected to a
known-good (huge!) antenna over the roof.
I have not been seeing this QRM:
(*) On the other side of the state (and the mountains) at my brother's
place, connected to a (different) poorly-constructed random-wire antenna
In each occasion the radio was hooked up to the same batteries, the same
ethernet cable, and the same netbook running KK.

I have for a while been thinking this is a grounding issue and have gotten
almost prepared to drill grounding holes through Pandora (and connect it to
a grounding rod less than 6' away from the radio?).  However I'm starting
to "feel" that this is not a grounding issue (although grounding the radio
would undoubtedly help, the power supply isn't even grounded right now).

A friend of mine has repeatedly suggested that I've got a cold solder join
somewhere in the radio, possibly exacerbated by my moving it across the
mountains.  However as far as I know (and have asked here) no combination
of signals internal to HPSDR results in a repeated 60 Khz signal.

My current focus is that this might be a front-end overload of some kind
from a regional transmitter, likely LF (this thing has a 60 MHz LPF so it
wouldn't be from above the ADC passband, right?).  Unfortunately it doesn't
look like the kind of HPF I'm looking for is sold in stores, Alex doesn't
list a manufacturer for T-50 coils and I was hoping to get this radio
working before evaluating whether to purchase the full Alex.

There's enough stuff swirling around this right now (elliptical filter
analysis, alex bom analysis, googling grounding braids vs 4 AWG, bathroom
sink vs grounding rod) that I'd love some input on how I can better resolve
this and get a radio I can actually hear WWV through the QRM.

On Sat, Feb 19, 2011 at 5:38 PM, EB4APL <eb4apl at cembreros.jazztel.es> wrote:

> ***** High Performance Software Defined Radio Discussion List *****
>
>
> **
> Hi,
>
> With a high probability, you are receiving QRM from a switching power
> supply.  It can be the monitor's one, a plasma TV, the Internet router, an
> electronic ballast from a lamp ...
>
> Begin switching off one at a time and you'll find the culprit.  In some
> cases it could be in a neighbor premises.
>
> 73 de Ignacio, EB4APL
>
>
> El 20/02/2011 0:36, Pat McGrath wrote:
>
> ***** High Performance Software Defined Radio Discussion List *****
>
>
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>   HPSDR PowerSDR  show spikes approximately every 60khz
>
> on my monitor.
>
> This occur on all bands  with antenna connected. If the antenna is
> disconnected the spikes are gone.
>
> Anyone have any idea what could cause this?
>
>
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