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PX3: Possible problem with display

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N0SA

PX3: Possible problem with display

I have just recently noticed that there is a continual spike that follows my cursor. It is internally generated. In CW mode it is away from my tuned signal by the amount of my CW side tone setting and can be switched to above or below the cursor depending on if I am in CW or CW-R.
These spikes occur with no antenna connected and are S4 to S5 in strength depending on band.
I did the Opposite Sideband Rejection adjustment but show no improvement.
I think something is either set wrong or I have an issue.
Any help or ideas are appreciated.
Larry
n0sa
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Don Wilhelm

Re: PX3: Possible problem with display

Larry,

I suspect hum, buzz, and noise pickup on the RX I/Q cable shield between
the KX3 and the PX3.
Try "Bonding" - run a heavy wire or strap between the KX3 and the PX3 in
parallel with the RX I/Q cable. The shield from old RG-8 coax works well.

73,
Don W3FPR

On 9/9/2016 10:12 AM, Larry Naumann wrote:
> I have just recently noticed that there is a continual spike that follows my cursor. It is internally generated. In CW mode it is away from my tuned signal by the amount of my CW side tone setting and can be switched to above or below the cursor depending on if I am in CW or CW-R.
> These spikes occur with no antenna connected and are S4 to S5 in strength depending on band.
> I did the Opposite Sideband Rejection adjustment but show no improvement.
> I think something is either set wrong or I have an issue.
> Any help or ideas are appreciated.
>

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N0SA

Re: PX3: Possible problem with display

Don
Thanks for the suggestion but that does not fix/improve the situation.
Looking at it further I also have spikes at roughly 23, 30 and 52Khz
above and below my cursor. The 52 Khz signal is at S4 the other two are
about S2. I can turn on the PX3 and look at the display with no antenna
connected and see these spikes on every band. If I disconnect the cables
to the KX3 the signals are still there but go down to S1 in strength. I
have even tried running both on separate battery supplies but the
problem is the same. The spikes are there even if I disconnect the I/Q
cable but the spikes are very small, as soon as the I/Q cable is plugged
in the spikes increase.
Larry
n0sa
On 9/9/2016 9:22 AM, Don Wilhelm wrote:

> Larry,
>
> I suspect hum, buzz, and noise pickup on the RX I/Q cable shield
> between the KX3 and the PX3.
> Try "Bonding" - run a heavy wire or strap between the KX3 and the PX3
> in parallel with the RX I/Q cable. The shield from old RG-8 coax
> works well.
>
> 73,
> Don W3FPR
>
> On 9/9/2016 10:12 AM, Larry Naumann wrote:
>> I have just recently noticed that there is a continual spike that
>> follows my cursor. It is internally generated. In CW mode it is away
>> from my tuned signal by the amount of my CW side tone setting and can
>> be switched to above or below the cursor depending on if I am in CW
>> or CW-R.
>> These spikes occur with no antenna connected and are S4 to S5 in
>> strength depending on band.
>> I did the Opposite Sideband Rejection adjustment but show no
>> improvement.
>> I think something is either set wrong or I have an issue.
>> Any help or ideas are appreciated.
>>
>
>

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Elecraft mailing list

Re: PX3: Possible problem with display

You will get spikes with no antenna where they are not covered up by band noise. Also if you have a really big spike near where you are tuning, try turning down the NB level in THE PX3 or turn the PX3 NB OFF.

Elecraft have explained about these spikes which are as a result of the switched mode regulators in the PX3, but they are not a problem when you have an antenna connected with band noise.

Let us know how that goes.

73 from David GM4JJJ

> On 9 Sep 2016, at 16:31, Larry Naumann <[hidden email]> wrote:
>
> Don
> Thanks for the suggestion but that does not fix/improve the situation. Looking at it further I also have spikes at roughly 23, 30 and 52Khz above and below my cursor. The 52 Khz signal is at S4 the other two are about S2. I can turn on the PX3 and look at the display with no antenna connected and see these spikes on every band. If I disconnect the cables to the KX3 the signals are still there but go down to S1 in strength. I have even tried running both on separate battery supplies but the problem is the same. The spikes are there even if I disconnect the I/Q cable but the spikes are very small, as soon as the I/Q cable is plugged in the spikes increase.
> Larry
> n0sa
>> On 9/9/2016 9:22 AM, Don Wilhelm wrote:
>> Larry,
>>
>> I suspect hum, buzz, and noise pickup on the RX I/Q cable shield between the KX3 and the PX3.
>> Try "Bonding" - run a heavy wire or strap between the KX3 and the PX3 in parallel with the RX I/Q cable. The shield from old RG-8 coax works well.
>>
>> 73,
>> Don W3FPR
>>
>>> On 9/9/2016 10:12 AM, Larry Naumann wrote:
>>> I have just recently noticed that there is a continual spike that follows my cursor. It is internally generated. In CW mode it is away from my tuned signal by the amount of my CW side tone setting and can be switched to above or below the cursor depending on if I am in CW or CW-R.
>>> These spikes occur with no antenna connected and are S4 to S5 in strength depending on band.
>>> I did the Opposite Sideband Rejection adjustment but show no improvement.
>>> I think something is either set wrong or I have an issue.
>>> Any help or ideas are appreciated.
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:[hidden email]
>
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Elecraft mailing list

Re: PX3: Possible problem with display

Further, I found this reply from Wayne (back in 2014)

On Oct 14, 2014, at 6:35 AM, jsdroyster at nc.rr.com wrote: > Our panadapter regularly (but not always) shows wide green bands of "noise" before the antenna is connected. When present, the bands are visible in the same panadapter screen location regardless of wbich band the radio is turned to, but the locations vary day to day (sometimes at the low end of the screen, other times in the middle). The white line on the screen rises to peaks above these green areas. 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 plot With the above setup, there will typically be no visible fixed spectral lines on the PX3. As described in the PX
3 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. The P3 uses a completely different method of acquiring the signal for spectral display: It digitally down converts the K3's 8.2-MHz I.F. This provides a S/N and spur advantage over an RX I/Q approach, but requires much more complex circuitry -- hence the difference in cost between the two units. Wayne N6KR

73 from David GM4JJJ

> On 9 Sep 2016, at 18:09, David Anderson via Elecraft <[hidden email]> wrote:
>
> You will get spikes with no antenna where they are not covered up by band noise. Also if you have a really big spike near where you are tuning, try turning down the NB level in THE PX3 or turn the PX3 NB OFF.
>
> Elecraft have explained about these spikes which are as a result of the switched mode regulators in the PX3, but they are not a problem when you have an antenna connected with band noise.
>
> Let us know how that goes.
>
> 73 from David GM4JJJ
>
>> On 9 Sep 2016, at 16:31, Larry Naumann <[hidden email]> wrote:
>>
>> Don
>> Thanks for the suggestion but that does not fix/improve the situation. Looking at it further I also have spikes at roughly 23, 30 and 52Khz above and below my cursor. The 52 Khz signal is at S4 the other two are about S2. I can turn on the PX3 and look at the display with no antenna connected and see these spikes on every band. If I disconnect the cables to the KX3 the signals are still there but go down to S1 in strength. I have even tried running both on separate battery supplies but the problem is the same. The spikes are there even if I disconnect the I/Q cable but the spikes are very small, as soon as the I/Q cable is plugged in the spikes increase.
>> Larry
>> n0sa
>>> On 9/9/2016 9:22 AM, Don Wilhelm wrote:
>>> Larry,
>>>
>>> I suspect hum, buzz, and noise pickup on the RX I/Q cable shield between the KX3 and the PX3.
>>> Try "Bonding" - run a heavy wire or strap between the KX3 and the PX3 in parallel with the RX I/Q cable. The shield from old RG-8 coax works well.
>>>
>>> 73,
>>> Don W3FPR
>>>
>>>> On 9/9/2016 10:12 AM, Larry Naumann wrote:
>>>> I have just recently noticed that there is a continual spike that follows my cursor. It is internally generated. In CW mode it is away from my tuned signal by the amount of my CW side tone setting and can be switched to above or below the cursor depending on if I am in CW or CW-R.
>>>> These spikes occur with no antenna connected and are S4 to S5 in strength depending on band.
>>>> I did the Opposite Sideband Rejection adjustment but show no improvement.
>>>> I think something is either set wrong or I have an issue.
>>>> Any help or ideas are appreciated.
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>> Message delivered to [hidden email]
>
> ______________________________________________________________
> Elecraft mailing list
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> Post: mailto:[hidden email]
>
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N0SA

Re: PX3: Possible problem with display

In reply to this post by Elecraft mailing list

David
Thanks for all the info. Wayne seems to have explained it fairly well.
I think there were a few contributing factors in my setup.
I have a new and quite a bit quieter antenna, thus less noise to cover
up the small spikes. I never had the NB on but I had the PRE AMP off on
20M. Most of the issues are now masked with more noise and higher gains.
I redid the OSN settings one more time and things seem to look better.
The whole issue started with 15M which I think needed the OSN to be
trimmed up a bit. Now all looks to be good. It was a combination of me
looking too close and one band needing a touchup OSN calibration.
Larry
n0sa
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