PX3 Problem?

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PX3 Problem?

Dave Sublette
I have had my PX3 for a little over a year (I think).  It has been used sparingly.  Until this afternoon, it has worked perfectly.  Now I see a spike in the center of the display and periodic spikes across the entire screen. Almost all are symmetrical in frequency and amplitude about the center line. There are some that are not symmetrical.  I have plugged and unplugged all the cables, taking care to see that each is fully into the socket.

So, perhaps I have a failure that requires returning to Elecraft?  Have any of you had the same experience?

73,

Dave, K4TO
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Re: PX3 Problem?

Matt Zilmer-3
Try unplugging the antenna to see if it's internally- or
externally-generated.  If the artifacts remain with no antenna, only one
of the I/Q signals is making it to the PX3. This may be due to the cable
or the KX3 or PX3 3.5mm sockets.  Try using a different M-M 3.5mm cable
and see if it makes a difference.

What you would see if only the I or Q signal were connected is a
symmetrical display of amplitude about the center (carrier) frequency.
Even with the "not symmetrical" spikes, I'd still guess that is the problem.

Had the same experience here with a failed / intermittent cable.

73,

matt W6NIA


On 7/16/2017 3:06 PM, Dave Sublette wrote:

> I have had my PX3 for a little over a year (I think).  It has been used sparingly.  Until this afternoon, it has worked perfectly.  Now I see a spike in the center of the display and periodic spikes across the entire screen. Almost all are symmetrical in frequency and amplitude about the center line. There are some that are not symmetrical.  I have plugged and unplugged all the cables, taking care to see that each is fully into the socket.
>
> So, perhaps I have a failure that requires returning to Elecraft?  Have any of you had the same experience?
>
> 73,
>
> Dave, K4TO
> ______________________________________________________________
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--
"A delay is better than a disaster."
-- unknown

Matt Zilmer, W6NIA
[Shiraz]

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Re: PX3 Problem?

Roger Meadows
In reply to this post by Dave Sublette
Sounds like a ground loop. I had something similar.  I unplugged the KX3 from the computer and it went away. I was able to use an USB hub and it was fine.

--
73 and Thanks,
Roger Meadows
AE4RM
QRP - Do More With Less


On July 16, 2017 at 6:06:20 PM, Dave Sublette ([hidden email]<mailto:[hidden email]>) wrote:

I have had my PX3 for a little over a year (I think). It has been used sparingly. Until this afternoon, it has worked perfectly. Now I see a spike in the center of the display and periodic spikes across the entire screen. Almost all are symmetrical in frequency and amplitude about the center line. There are some that are not symmetrical. I have plugged and unplugged all the cables, taking care to see that each is fully into the socket.

So, perhaps I have a failure that requires returning to Elecraft? Have any of you had the same experience?

73,

Dave, K4TO
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Re: PX3 Problem?

Dave Sublette
In reply to this post by Dave Sublette
Tnx Roger and Matt.  Roger — I don’t have the KX3/PX3 interfaced with the audio on the computer.  I do have the usb port connected.

Matt — I believe it is the 2.5 mm jacks that carry the Rx I/Q between the KX3 and PX3.  I unplugged the antenna and the spikes are still there.  I unplugged the Rx I/Q plug from the PX3 and the irregularly space spikes went away and the regularly spaced spikes were still there at the same levels as when the cable was plugged in.

I’m still thinking there is a failure in the PX3.

Dave

> On Jul 16, 2017, at 6:06 PM, Dave Sublette <[hidden email]> wrote:
>
> I have had my PX3 for a little over a year (I think).  It has been used sparingly.  Until this afternoon, it has worked perfectly.  Now I see a spike in the center of the display and periodic spikes across the entire screen. Almost all are symmetrical in frequency and amplitude about the center line. There are some that are not symmetrical.  I have plugged and unplugged all the cables, taking care to see that each is fully into the socket.
>
> So, perhaps I have a failure that requires returning to Elecraft?  Have any of you had the same experience?
>
> 73,
>
> Dave, K4TO
> ______________________________________________________________
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Re: PX3 Problem?

ve3ibw
Just out of curiosity, has any other wall wart or other device been plugged
in near the px3-kx3 recently?

Interestly enough, just this morning I saw new noise I hadn't seen before.
  It turned out to be a wall wart that was charging a car booster battery
pack and it was about 4-5 inches from the kx3.  I moved the kx3 away from
the wall wart about 10 inches and the noise reduced.

I zoomed the PX3 in to a 2khz span and I saw a spike at 60hz, 180hz, and
300hz symmetrically about the centre frequency.

I moved the wall wart to another plug about 3 feet away, no more qrm.

Hope this helps you.

Regards
Brian
VE3IBW
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Regards,
Brian
VE3IBW
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Re: PX3 Problem?

Dale Boresz
In reply to this post by Dave Sublette
Dave, make sure that the preamp is engaged on your KX3. If the preamp is
off and you are receiving on a quiet band, you'll see "stuff" that would
normally be covered by the band noise. Turn on the preamp, and the
artifacts that you're seeing should be pushed below the noise floor of just
about any band.

73,

Dale - WA8SRA


On Sun, Jul 16, 2017 at 6:06 PM, Dave Sublette <[hidden email]> wrote:

> I have had my PX3 for a little over a year (I think).  It has been used
> sparingly.  Until this afternoon, it has worked perfectly.  Now I see a
> spike in the center of the display and periodic spikes across the entire
> screen. Almost all are symmetrical in frequency and amplitude about the
> center line. There are some that are not symmetrical.  I have plugged and
> unplugged all the cables, taking care to see that each is fully into the
> socket.
>
> So, perhaps I have a failure that requires returning to Elecraft?  Have
> any of you had the same experience?
>
> 73,
>
> Dave, K4TO
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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Re: PX3 Problem?

Dave Sublette
Good point.  However I am on 20 meters, which really doesn’t need the preamp.  Besides, the spikes are 40 dB high or so.  No, this behavior is definitely looking like a failure.  I have one more thing to try.  I will carry it out to the shop in my garage and plug it in.  If it is the same there as in here, it’s not any external influence.  Thanks for hanging in there with me.

73,

Dave

> On Jul 16, 2017, at 9:56 PM, Dale Boresz <[hidden email]> wrote:
>
> Dave, make sure that the preamp is engaged on your KX3. If the preamp is off and you are receiving on a quiet band, you'll see "stuff" that would normally be covered by the band noise. Turn on the preamp, and the artifacts that you're seeing should be pushed below the noise floor of just about any band.
>
> 73,
>
> Dale - WA8SRA
>
>
> On Sun, Jul 16, 2017 at 6:06 PM, Dave Sublette <[hidden email] <mailto:[hidden email]>> wrote:
> I have had my PX3 for a little over a year (I think).  It has been used sparingly.  Until this afternoon, it has worked perfectly.  Now I see a spike in the center of the display and periodic spikes across the entire screen. Almost all are symmetrical in frequency and amplitude about the center line. There are some that are not symmetrical.  I have plugged and unplugged all the cables, taking care to see that each is fully into the socket.
>
> So, perhaps I have a failure that requires returning to Elecraft?  Have any of you had the same experience?
>
> 73,
>
> Dave, K4TO
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft <http://mailman.qth.net/mailman/listinfo/elecraft>
> Help: http://mailman.qth.net/mmfaq.htm <http://mailman.qth.net/mmfaq.htm>
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> This list hosted by: http://www.qsl.net <http://www.qsl.net/>
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Re: PX3 Problem?

Don Wilhelm
Dave,

The KX3 is designed to be operated with the preamp on most of the time.
The only reason to turn it off is when extremely strong signals are
encountered.

The preamp eliminates many spurious signals that are actually out of
band due to its signal rejection "filtering".  That has nothing to do
with the sensitivity, and it can kill extraneous results such as you are
seeing.

If it makes those responses substantial with the preamp on, then there
may be a problem to be addressed.

73,
Don W3FPR

On 7/16/2017 10:07 PM, Dave Sublette wrote:
> Good point.  However I am on 20 meters, which really doesn’t need the preamp.  Besides, the spikes are 40 dB high or so.  No, this behavior is definitely looking like a failure.  I have one more thing to try.  I will carry it out to the shop in my garage and plug it in.  If it is the same there as in here, it’s not any external influence.  Thanks for hanging in there with me.
>
> 73,
>
> Dave
>> On Jul 16, 2017, at 9:56 PM, Dale Boresz <[hidden email]> wrote:
>>
>> Dave, make sure that the preamp is engaged on your KX3. If the preamp is off and you are receiving on a quiet band, you'll see "stuff" that would normally be covered by the band noise. Turn on the preamp, and the artifacts that you're seeing should be pushed below the noise floor of just about any band.
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Re: PX3 Problem?

Dave Sublette
Using just one of 20 “extra” spurs, I measuredthe spur peak at -90 with the preamp on. Base line is -125 with it on.

Turning off the preamp, the peak is -75, base line -112.

The s/n remains basically with preamp on and off.  The main thing is, Those spurs were not there previously.

I just took the PX3 out to the shop and hooked it to another supply.  The spurs are still there.

Dave

> On Jul 16, 2017, at 10:22 PM, Don Wilhelm <[hidden email]> wrote:
>
> Dave,
>
> The KX3 is designed to be operated with the preamp on most of the time. The only reason to turn it off is when extremely strong signals are encountered.
>
> The preamp eliminates many spurious signals that are actually out of band due to its signal rejection "filtering".  That has nothing to do with the sensitivity, and it can kill extraneous results such as you are seeing.
>
> If it makes those responses substantial with the preamp on, then there may be a problem to be addressed.
>
> 73,
> Don W3FPR
>
> On 7/16/2017 10:07 PM, Dave Sublette wrote:
>> Good point.  However I am on 20 meters, which really doesn’t need the preamp.  Besides, the spikes are 40 dB high or so.  No, this behavior is definitely looking like a failure.  I have one more thing to try.  I will carry it out to the shop in my garage and plug it in.  If it is the same there as in here, it’s not any external influence.  Thanks for hanging in there with me.
>> 73,
>> Dave
>>> On Jul 16, 2017, at 9:56 PM, Dale Boresz <[hidden email]> wrote:
>>>
>>> Dave, make sure that the preamp is engaged on your KX3. If the preamp is off and you are receiving on a quiet band, you'll see "stuff" that would normally be covered by the band noise. Turn on the preamp, and the artifacts that you're seeing should be pushed below the noise floor of just about any band.

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Re: PX3 Problem?

Dale Boresz
Hello Dave,

Just checked my KX3/PX3 and with no antenna, I am also seeing spur peaks
about 25 to 30 dB above the noise floor.

With the PX3 SPAN set to 30 KHz:

On 20 meters, when I turn the preamp ON (20dB preamp setting), and connect
my HexBeam, I only see 20m band noise at about -112 dBm; there is no sign
of the spurs. If I turn the preamp OFF, then I do see some of the spurs
about 5 - 8 dBm above the noise floor.

To provide some idea of my actual noise floor on 20 meters, my P3 indicates
-124 dBm (also with a SPAN of 30 KHz), and three other SDR radios also read
-124 dBm on their respective panadapter displays, each set to a span of 30
KHz.

Do you still see any of the spurs with your antenna connected on 20 meters,
and the 20 dB preamp engaged?

73,

Dale - WA8SRA






On Sun, Jul 16, 2017 at 10:47 PM, Dave Sublette <[hidden email]> wrote:

> Using just one of 20 “extra” spurs, I measuredthe spur peak at -90 with
> the preamp on. Base line is -125 with it on.
>
> Turning off the preamp, the peak is -75, base line -112.
>
> The s/n remains basically with preamp on and off.  The main thing is,
> Those spurs were not there previously.
>
> I just took the PX3 out to the shop and hooked it to another supply.  The
> spurs are still there.
>
> Dave
> > On Jul 16, 2017, at 10:22 PM, Don Wilhelm <[hidden email]>
> wrote:
> >
> > Dave,
> >
> > The KX3 is designed to be operated with the preamp on most of the time.
> The only reason to turn it off is when extremely strong signals are
> encountered.
> >
> > The preamp eliminates many spurious signals that are actually out of
> band due to its signal rejection "filtering".  That has nothing to do with
> the sensitivity, and it can kill extraneous results such as you are seeing.
> >
> > If it makes those responses substantial with the preamp on, then there
> may be a problem to be addressed.
> >
> > 73,
> > Don W3FPR
> >
> > On 7/16/2017 10:07 PM, Dave Sublette wrote:
> >> Good point.  However I am on 20 meters, which really doesn’t need the
> preamp.  Besides, the spikes are 40 dB high or so.  No, this behavior is
> definitely looking like a failure.  I have one more thing to try.  I will
> carry it out to the shop in my garage and plug it in.  If it is the same
> there as in here, it’s not any external influence.  Thanks for hanging in
> there with me.
> >> 73,
> >> Dave
> >>> On Jul 16, 2017, at 9:56 PM, Dale Boresz <[hidden email]> wrote:
> >>>
> >>> Dave, make sure that the preamp is engaged on your KX3. If the preamp
> is off and you are receiving on a quiet band, you'll see "stuff" that would
> normally be covered by the band noise. Turn on the preamp, and the
> artifacts that you're seeing should be pushed below the noise floor of just
> about any band.
>
>
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Re: PX3 Problem?

Elecraft mailing list
In reply to this post by Dave Sublette
One other thing, have you perhaps got the PX3 Noise Blanker switched on and the PX3 NB level turned up high? That causes spikes at the centre.  (I am not referring to the KX3 noise blanker)

73 from David GM4JJJ

> On 16 Jul 2017, at 23:06, Dave Sublette <[hidden email]> wrote:
>
> I have had my PX3 for a little over a year (I think).  It has been used sparingly.  Until this afternoon, it has worked perfectly.  Now I see a spike in the center of the display and periodic spikes across the entire screen. Almost all are symmetrical in frequency and amplitude about the center line. There are some that are not symmetrical.  I have plugged and unplugged all the cables, taking care to see that each is fully into the socket.
>
> So, perhaps I have a failure that requires returning to Elecraft?  Have any of you had the same experience?
>
> 73,
>
> Dave, K4TO
> ______________________________________________________________
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Re: PX3 Problem?

Elecraft mailing list
In reply to this post by Dave Sublette
This comes up quite often, and here is a reply from Wayne about it. You can check your PX3 as follows.

> Are you using a PX3 or P3? Assuming it's a PX3, try this:
>
> - make sure RX I/Q is set to ON (KX3 menu)
> - make sure the PX3->KX3 cables are fully seated
> - connect an antenna to the KX3
> - switch to 20 meters
> - turn the preamp ON and set the PREAMP menu entry on the KX3 to 20 dB
> - set the PX3's SPAN to 50 kHz or lower
> - adjust the REF level so the "grass" (noise floor) is close to the bottom of the spectralplot
>
> With the above setup, there will typically be no visible fixed spectral lines on the PX3.
>
> As described in the PX3 FAQ on our web site, very wide SPAN settings and low front-end gain (e.g., turning off the preamp) will reduce the signal-to-noise ratio of an RX I/Q-based pandapter, including making wideband spurs more apparent. The same limitations apply when using the KX3 (or other quadrature downconversion radio) with a PC sound card. Typically this doesn't impact usability, e.g. locating signals of interest. In fact most sound cards are limited to displaying about 48 kHz of spectrum, while the PX3 can go wider thanks to its high-performance/high-speed A-to-D converter.

73 from David GM4JJJ

> On 16 Jul 2017, at 23:47, Dave Sublette <[hidden email]> wrote:
>
> Tnx Roger and Matt.  Roger — I don’t have the KX3/PX3 interfaced with the audio on the computer.  I do have the usb port connected.
>
> Matt — I believe it is the 2.5 mm jacks that carry the Rx I/Q between the KX3 and PX3.  I unplugged the antenna and the spikes are still there.  I unplugged the Rx I/Q plug from the PX3 and the irregularly space spikes went away and the regularly spaced spikes were still there at the same levels as when the cable was plugged in.
>
> I’m still thinking there is a failure in the PX3.
>
> Dave
>> On Jul 16, 2017, at 6:06 PM, Dave Sublette <[hidden email]> wrote:
>>
>> I have had my PX3 for a little over a year (I think).  It has been used sparingly.  Until this afternoon, it has worked perfectly.  Now I see a spike in the center of the display and periodic spikes across the entire screen. Almost all are symmetrical in frequency and amplitude about the center line. There are some that are not symmetrical.  I have plugged and unplugged all the cables, taking care to see that each is fully into the socket.
>>
>> So, perhaps I have a failure that requires returning to Elecraft?  Have any of you had the same experience?
>>
>> 73,
>>
>> Dave, K4TO
>> ______________________________________________________________
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>
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Re: PX3 Problem?

Dave Sublette
Good morning all,

I read all of the latest suggestions, and they were good ones.  I got into the menu and determined that the noise blanker was off, as it should have been.  The PX3 seems to be working properly now and the main thing that helped was turning on the preamp in the KX3.  I use the KX3 on 28 MHz as an IF for several VHF transverters.  Since I have mast mounted preamps for each band, I thought it would be better to turn off the internal preamp in the KX3.  BUT — I also work HF with the KX3 and that is where I was having the “spur problem”. So, when I turned the preamp back on in the KX3 it all went away.  

I thank you all for your patient and kind help.  I learn a little every time I go through one of these exercises.  It’s good for me to keep up.  60 years ago, when I got my first ticket, the equipment to do what the KX3 does today would have filled a wall in my shack. In fact, there wasn’t any equipment available to do what the KX3 does in some ways.  It’s a great thing, this radio stuff.  But I think the best thing about it is the people we interact with.

73 all,

Dave, K4TO

> On Jul 17, 2017, at 4:42 AM, David Anderson <[hidden email]> wrote:
>
> This comes up quite often, and here is a reply from Wayne about it. You can check your PX3 as follows.
>
>> Are you using a PX3 or P3? Assuming it's a PX3, try this:
>>
>> - make sure RX I/Q is set to ON (KX3 menu)
>> - make sure the PX3->KX3 cables are fully seated
>> - connect an antenna to the KX3
>> - switch to 20 meters
>> - turn the preamp ON and set the PREAMP menu entry on the KX3 to 20 dB
>> - set the PX3's SPAN to 50 kHz or lower
>> - adjust the REF level so the "grass" (noise floor) is close to the bottom of the spectral <x-apple-data-detectors://7>plot
>>
>> With the above setup, there will typically be no visible fixed spectral lines on the PX3.
>>
>> As described in the PX3 FAQ on our web site, very wide SPAN settings and low front-end gain (e.g., turning off the preamp) will reduce the signal-to-noise ratio of an RX I/Q-based pandapter, including making wideband spurs more apparent. The same limitations apply when using the KX3 (or other quadrature downconversion radio) with a PC sound card. Typically this doesn't impact usability, e.g. locating signals of interest. In fact most sound cards are limited to displaying about 48 kHz of spectrum, while the PX3 can go wider thanks to its high-performance/high-speed A-to-D converter.
>
> 73 from David GM4JJJ
>
> On 16 Jul 2017, at 23:47, Dave Sublette <[hidden email] <mailto:[hidden email]>> wrote:
>
>> Tnx Roger and Matt.  Roger — I don’t have the KX3/PX3 interfaced with the audio on the computer.  I do have the usb port connected.
>>
>> Matt — I believe it is the 2.5 mm jacks that carry the Rx I/Q between the KX3 and PX3.  I unplugged the antenna and the spikes are still there.  I unplugged the Rx I/Q plug from the PX3 and the irregularly space spikes went away and the regularly spaced spikes were still there at the same levels as when the cable was plugged in.
>>
>> I’m still thinking there is a failure in the PX3.
>>
>> Dave
>>> On Jul 16, 2017, at 6:06 PM, Dave Sublette <[hidden email] <mailto:[hidden email]>> wrote:
>>>
>>> I have had my PX3 for a little over a year (I think).  It has been used sparingly.  Until this afternoon, it has worked perfectly.  Now I see a spike in the center of the display and periodic spikes across the entire screen. Almost all are symmetrical in frequency and amplitude about the center line. There are some that are not symmetrical.  I have plugged and unplugged all the cables, taking care to see that each is fully into the socket.
>>>
>>> So, perhaps I have a failure that requires returning to Elecraft?  Have any of you had the same experience?
>>>
>>> 73,
>>>
>>> Dave, K4TO
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