Sent: Sunday, February 9, 2014 10:11 PM
To: mzil...@roadrunner.com; elecraft
Subject: Re: [Elecraft] KX3: nearby noise post-mortem
I should have mentioned this specifically, but I was operating the KX3 strictly
from batteries at the time.
Connecting a 13.8V source to it (one that was plugged into
I think that is very likely to be the case, yes. It's worth noting that it
is a somewhat badly unbalanced antenna at the moment. Normally it would
have a set of el-cheapo tape measures attached as radials, but the weather
and time have not been kind to them, so they're not currently attached...
t
Nicklas Johnson
To: Ralf Wilhelm
Cc: elecraft
Sent: Monday, February 10, 2014 10:49 AM
Subject: Re: [Elecraft] KX3: nearby noise post-mortem
Interesting, and if I may ask a potentially-dumb question, what do we
really mean when we use the word "isolation" in this context, and ho
You have written earlier that you could pull the coax plug "half out"
(disconnecting the shield) and that this also helped. So maybe you have common
mode current on the coax which would also increase the coupling to the wiring
(because not only the antenna itself but also the coax would emit th
Makes sense. And that's why the RX SHFT also works, because then the
reflected signal is shifted away from the RX frequency by the same amount
as the shift. That was a great explanation, and I thank you for it!
Another solution in my case, then, might be to just move the antenna
further away fro
The problem with all receivers using a local oscillator (direct conversion or
superhet) is that they emit a small part of the local oscillator power via the
mixer to the antenna port (maybe a typical number of L.O. to R.F. Port
Isolation of a mixer is 40 dB or something like that). In a superhet
Interesting, and if I may ask a potentially-dumb question, what do we
really mean when we use the word "isolation" in this context, and how does
it provide the benefit of keeping the buzz out of the detector (or to ask
the question in the reverse, how does the buzz get in, in the absence of
additio
Hi Nick,
Turning on the preamp increases the isolation between the local oscillator and
the antenna port. I also wasn't sure if my "buzz" went away when I turned on
the preamp (I couldn't hear it any more) but I used the spectral display of the
MixW-Software and the microphone of my laptop to c
Now that you mention it, I did notice the buzz went away when I turned on
the preamp, but I thought it was just my imagination or that the static had
just become sufficiently loud that my own hearing wasn't responding to it
anymore.
Nick
On 10 February 2014 03:02, Ralf Wilhelm wrote:
>
>
Nick,
The wire should run outside. It can and should be buried. It does not
have to be down very far, but deep enough it will not be damaged by the
lawn mower or shovels if you should dig in that area.
A perimeter wire around the house would not be a bad idea either, it can
divert a lightnin
My guess would be that the local oscillator of the KX3 (which is on the rx qrg)
is emitted via the shield of the coax cable (common mode?) "received" by the
charger's usb cable, modulated with the 60Hz by non-linearities in the charger
and than re-emitted (maybe by the wiring a a whole) and th
That's a really good point, and in fact I have it on my 'to do' list to get the
bonding done correctly. It's complicated by the ground rods being on the
opposite side of the house, and the utilities running underground without an
exposed ground stake by the utility box outside.
I think code al
Nick,
I suspect your antenna ground stakes were not connected to the utility
entry ground rod with a #6 or larger copper wire. The earth creates
resistance between the antenna ground stake(s) and the AC ground in your
home.
Now, that USB phone charger power supply connects to at least the A
I'm puzzled by all of this, Nick. I'll think on it.
73,
matt W6NIA
On Sun, 9 Feb 2014 20:11:13 -0800, you wrote:
>I should have mentioned this specifically, but I was operating the KX3
>strictly from batteries at the time.
Matt Zilmer, W6NIA
--
"Give me six hours to chop down a tree and I wil
I should have mentioned this specifically, but I was operating the KX3
strictly from batteries at the time.
Connecting a 13.8V source to it (one that was plugged into the house power)
didn't really change whether the 'buzz' was present or not.
The only thing that changed it was either unplugging
Hi Nick,
After reading your reply, I think I have an idea.
I've had the same problem in a mobile setting, where good grounds are
scarce and there is a lot of transient noise around. If -somehow- the
noise put off by the charger were to get onto the 12V line into the
KX3, you might get this effec
In this case the 'transmitter' was the switching power supply in a USB cell
phone charger plugged into an outlet in relatively close proximity to the
antenna (other side of the wall of the house).
The charger plugged in by itself put off a little noise. With the USB
cable plugged into it and stre
Hi Nick,
RX SHFT is normally used to cancel the effects of AM detection of very
strong signals that blow by the mixer and enter the detector -
overload. Since enabling RX SHFT cured this 60Hz+harmonics problem,
it seems likely that you were copying a strong signal with little or
no modulation. Y
Hi all,
I'm trying to make sure that I understand something kind of weird that I
ran across today; I hate resolving a problem without fully appreciating
everything that was causing it.
Since 10M was pretty active today, I thought I'd pop on, and since the
ground was nice and wet, I thought I'd gi
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