As this message doesn't appear to be on the forum, I guess the attachments
were the problem, so I'm reposting the original and I've put the attachments
into my dropbox at
https://dl.dropboxusercontent.com/u/65397105/KX3%20Test%2027-06-2014%201002.jpg
Which is with my KX3 switched off and
https://dl.dropboxusercontent.com/u/65397105/KX3%20Test%2027-06-2014%201005.jpg
Which is with my KX3 switched on and set to 7.080MHz USB.
Dave (G0DJA)
----- Original Message -----
Sent: Friday, June 27, 2014 9:43 AM
Subject: Re: [Elecraft] KX3 - UHF emissions
I've just done a couple of tests using an RF Explorer portable spectrum
analyser set to monitor between 15MHz and 614MHz. I can 'zoom in' if
necessary but kept it wide in the first case to have an overview of as
wide
a frequency range as possible. The antenna is the "Ngoya NA-773
144/430MHz"
whip antenna supplied with the analyser with the whip fully retracted.The
analyser and fitted antenna are about 15cm (6inches) away from the KX3.
My KX3 has leads plugged into the RX I/Q socket, the Phones socket, the
ACC1
socket and a 13.8V supply to the 9-15V DC socket. No cable connected to
the
ACC2 socket. None of the leads have any RF beads on them, that I can see
anyway. The DC, ACC1 and RX I/Q leads are the ones suplied by Elecraft.
If the screenshots get taken off before they get onto the reflector, I'll
put them in a dropbox folder and will post a link.
The 1st screenshot shows the situation with the KX3 switched off, date
stamped 27-06-2014 1002. With the KX3 swiched off I see a steady signal at
389.999MHz (-83dBm) and, as the red line shows, there's an occasional
signal
at 143.571MHz (-78.5dBm). There's also another occasional signal at
422.142MHz (-78.5dBm).
The second screen shot is with the KX3 switched on, date stamped
27-06-2014
1005, frequency set to 7.080Mhz USB. With the KX3 on I am seeing a rise
in
the noise floor at a whole range of frequencies, but no specific single
frequency spike, other than the ones that I see with the KX3 switched off
of
course, as yet.
I'll set the analyser to monitor just the VHF/UHF spectrum next and see if
I
can track any specific carriers down.
Dave (G0DJA)
----- Original Message -----
From: "Darren Long"
To: <[email protected]>; "Wayne Burdick" <[email protected]>;
<[email protected]>
Sent: Thursday, June 26, 2014 11:30 PM
Subject: Re: [Elecraft] KX3 - UHF emissions
My I/Q cable assembly includes a short adapter with a 2.5mm plug and
in-line
3.5mm socket, followed by an inline stereo line-isolator and then on to
to
the
extension cable to the PC (all other connections being with 3.5mm TRS
other than
the one on the rig).
Without nothing connected to the KX3, I'm seeing the spur on 389.4MHz at
about
-68dB, as observed on my USRP using my loft discone. The noise floor is
about -80dB.
Plugging in the adapter without the 2 turn choke boosts the receive
signal
to
about -46dB.
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