Re: [Elecraft] Phantom signals

[ab2tc]

Hi again,

But if they are fixed (not following the tuning of the K3) you should be
able to tune to them and hear them in your K3 without any computers or SDRs
running. So Don's advice to turn everything except the K3 off seems sound to
me.

AB2TC - Knut


Don Wilhelm wrote
> Pete,
> 
> Any chance you can borrow a P3 to see if those spurs are present both 
> with and without the computer?
> That would be a good test if you can manage it.
> 
> The other thing that may help is to bond the K3 to the other gear, 
> following the paths of the IF out coax and also the audio cables. Bond 
> from box to box rather than trying to "ground" everything to a single 
> point (which may cause additional noise pickup.  Use the information on 
> that subject from Jim Brown K9YC.
> If everything else other than the K3 is plastic cased, bond to BNC 
> connector shells and/or computer I/O connector jackscrews.
> 
> 73,
> Don W3FPR
> 
> On 11/27/2018 9:44 PM, N4ZR wrote:
>>
>> Trouble is, my computer supplies N1MM+, including its spectrum 
>> display. Catch 22
>>
>>
> 





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Re: [Elecraft] Phantom signals

[Don Wilhelm]

Pete,

Any chance you can borrow a P3 to see if those spurs are present both 
with and without the computer?

That would be a good test if you can manage it.

The other thing that may help is to bond the K3 to the other gear, 
following the paths of the IF out coax and also the audio cables. Bond 
from box to box rather than trying to "ground" everything to a single 
point (which may cause additional noise pickup.  Use the information on 
that subject from Jim Brown K9YC.
If everything else other than the K3 is plastic cased, bond to BNC 
connector shells and/or computer I/O connector jackscrews.


73,
Don W3FPR

On 11/27/2018 9:44 PM, N4ZR wrote:


Trouble is, my computer supplies N1MM+, including its spectrum 
display. Catch 22





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Re: [Elecraft] Phantom signals

[N4ZR]

Trouble is, my computer supplies N1MM+, including its spectrum display.  
Catch 22


73, Pete N4ZR
Check out the Reverse Beacon Network
at , now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

On 11/27/2018 6:16 PM, Don Wilhelm wrote:
Another thing to suspect is noise generated by a computer, or ethernet 
modems and routers and being routed to the K3 and P3 via the K3 to 
computer connection.  I believe that is why Tom suggested winding the 
USB cable through a type 31 ferrite core.  BTW, that core should be 
near the computer end).


Disconnect and power down the computer to see if that is contributing 
to the "spurs".


73,
Don W3FPR

On 11/27/2018 5:57 PM, ab2tc wrote:

Hi,

Absolutely no sign of any of these spurs here with my K3S. Since they 
are at
constant frequencies they must be coming in through the K3 front end 
(*not*
at the IF level). So either your K3 front end is generating them 
(which it
shouldn't) or they are present in your environment. Again, since they 
are at
constant frequencies, the P3 or any other SDR connected to the K3 IF 
output
should not be the culprit. Send me an E-mail and I will give you 
spectral
plots collected with LP-PAN/NAP3 with K3 connected to a well shielded 
dummy

load.

AB2TC


tomb18 wrote
This is pretty common. One thing that can help is to wrap your USB 
cable

through an ft241 31 to rid. About 6 turns gets rig of lots of picked up
garbage. 73 Tom



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Re: [Elecraft] Phantom signals

[Grant Youngman]

I sometimes notice a host of phantoms that follow the tuning, but only when the 
preamp is off. Turning on the preamp generally kills them all. 

This doesn’t help with the fixed frequency junk being generated by the myriad 
of switchers in the house, though. Different issue. 

Grant NQ5T

> On Nov 27, 2018, at 6:16 PM, Don Wilhelm  wrote:
> 
> Another thing to suspect is noise generated by a computer, or ethernet modems 
> and routers and being routed to the K3 and P3 via the K3 to computer 
> connection.  I believe that is why Tom suggested winding the USB cable 
> through a type 31 ferrite core.  BTW, that core should be near the computer 
> end).
> 
> Disconnect and power down the computer to see if that is contributing to the 
> "spurs".
> 
> 73,
> Don W3FPR
> 
>> 
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Re: [Elecraft] Phantom signals

[Don Wilhelm]

Another thing to suspect is noise generated by a computer, or ethernet 
modems and routers and being routed to the K3 and P3 via the K3 to 
computer connection.  I believe that is why Tom suggested winding the 
USB cable through a type 31 ferrite core.  BTW, that core should be near 
the computer end).


Disconnect and power down the computer to see if that is contributing to 
the "spurs".


73,
Don W3FPR

On 11/27/2018 5:57 PM, ab2tc wrote:

Hi,

Absolutely no sign of any of these spurs here with my K3S. Since they are at
constant frequencies they must be coming in through the K3 front end (*not*
at the IF level). So either your K3 front end is generating them (which it
shouldn't) or they are present in your environment. Again, since they are at
constant frequencies, the P3 or any other SDR connected to the K3 IF output
should not be the culprit. Send me an E-mail and I will give you spectral
plots collected with LP-PAN/NAP3 with K3 connected to a well shielded dummy
load.

AB2TC


tomb18 wrote

This is pretty common. One thing that can help is to wrap your USB cable
through an ft241 31 to rid. About 6 turns gets rig of lots of picked up
garbage. 73 Tom



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Re: [Elecraft] Phantom signals

[ab2tc]

Hi,

Absolutely no sign of any of these spurs here with my K3S. Since they are at
constant frequencies they must be coming in through the K3 front end (*not*
at the IF level). So either your K3 front end is generating them (which it
shouldn't) or they are present in your environment. Again, since they are at
constant frequencies, the P3 or any other SDR connected to the K3 IF output
should not be the culprit. Send me an E-mail and I will give you spectral
plots collected with LP-PAN/NAP3 with K3 connected to a well shielded dummy
load.

AB2TC


tomb18 wrote
> This is pretty common. One thing that can help is to wrap your USB cable
> through an ft241 31 to rid. About 6 turns gets rig of lots of picked up
> garbage. 73 Tom
> 
> 
> Sent from my Samsung Galaxy smartphone.
>  Original message From: Fred Jensen <

> k6dgw@

> > Date: 2018-11-26  6:14 PM  (GMT-05:00) To: 

> elecraft@.qth

>  Subject: Re: [Elecraft] Phantom signals 
> I have a clean carrier at 7039.6, about S4, but nothing on 20.  It's 
> pretty hard to build a double conversion superhet that doesn't have a 
> few weak spurs.
> 
> 73,
> Fred ["Skip"] K6DGW
> Sparks NV DM09dn
> Washoe County
> 
> On 11/26/2018 2:20 PM, N4ZR wrote:
>> I recently started using N1MM+'s spectrum display with my K3, and it 
>> made me notice that I have some phantom signals on the display. 
>> Specifically, there are steady carriers at 14039.6 and 28039.6. Each 
>> of these carriers has "sidebands" spaced 1 KHZ apart on either side. 
>> There is a slight AC roughness to the tones as heard in CW mode, 
>> particularly on 20M.  On 7039.6 and 21039.6 a single carrier is 
>> audible, much weaker than on 20 or 10 meters.
>>
>> Disconnecting the antenna from the K3 does not affect these signals, 
>> nor does disconnecting my Airspy HF+ from the IF Out jack.
>>
>> Any idea what these might be?  Because they are discrete frequencies 
>> and relatively weak, they aren't particularly an operational problem, but
>>
>> 73, Pete N4ZR
>> Check out the Reverse Beacon Network
>> at <http://reversebeacon.net>;, now
>> spotting RTTY activity worldwide.
>> For spots, please use your favorite
>> "retail" DX cluster.
> 
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Re: [Elecraft] Phantom signals

[tomb18]

This is pretty common. One thing that can help is to wrap your USB cable 
through an ft241 31 to rid. About 6 turns gets rig of lots of picked up 
garbage. 73 Tom


Sent from my Samsung Galaxy smartphone.
 Original message From: Fred Jensen  Date: 
2018-11-26  6:14 PM  (GMT-05:00) To: elecraft@mailman.qth.net Subject: Re: 
[Elecraft] Phantom signals 
I have a clean carrier at 7039.6, about S4, but nothing on 20.  It's 
pretty hard to build a double conversion superhet that doesn't have a 
few weak spurs.

73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 11/26/2018 2:20 PM, N4ZR wrote:
> I recently started using N1MM+'s spectrum display with my K3, and it 
> made me notice that I have some phantom signals on the display. 
> Specifically, there are steady carriers at 14039.6 and 28039.6. Each 
> of these carriers has "sidebands" spaced 1 KHZ apart on either side. 
> There is a slight AC roughness to the tones as heard in CW mode, 
> particularly on 20M.  On 7039.6 and 21039.6 a single carrier is 
> audible, much weaker than on 20 or 10 meters.
>
> Disconnecting the antenna from the K3 does not affect these signals, 
> nor does disconnecting my Airspy HF+ from the IF Out jack.
>
> Any idea what these might be?  Because they are discrete frequencies 
> and relatively weak, they aren't particularly an operational problem, but
>
> 73, Pete N4ZR
> Check out the Reverse Beacon Network
> at <http://reversebeacon.net>, now
> spotting RTTY activity worldwide.
> For spots, please use your favorite
> "retail" DX cluster.

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Re: [Elecraft] Phantom signals

[Fred Jensen]

I have a clean carrier at 7039.6, about S4, but nothing on 20.  It's 
pretty hard to build a double conversion superhet that doesn't have a 
few weak spurs.


73,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 11/26/2018 2:20 PM, N4ZR wrote:
I recently started using N1MM+'s spectrum display with my K3, and it 
made me notice that I have some phantom signals on the display. 
Specifically, there are steady carriers at 14039.6 and 28039.6. Each 
of these carriers has "sidebands" spaced 1 KHZ apart on either side. 
There is a slight AC roughness to the tones as heard in CW mode, 
particularly on 20M.  On 7039.6 and 21039.6 a single carrier is 
audible, much weaker than on 20 or 10 meters.


Disconnecting the antenna from the K3 does not affect these signals, 
nor does disconnecting my Airspy HF+ from the IF Out jack.


Any idea what these might be?  Because they are discrete frequencies 
and relatively weak, they aren't particularly an operational problem, but


73, Pete N4ZR
Check out the Reverse Beacon Network
at , now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.


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[Elecraft] Phantom signals

[N4ZR]

I recently started using N1MM+'s spectrum display with my K3, and it 
made me notice that I have some phantom signals on the display. 
Specifically, there are steady carriers at 14039.6 and 28039.6. Each of 
these carriers has "sidebands" spaced 1 KHZ apart on either side. There 
is a slight AC roughness to the tones as heard in CW mode, particularly 
on 20M.  On 7039.6 and 21039.6 a single carrier is audible, much weaker 
than on 20 or 10 meters.


Disconnecting the antenna from the K3 does not affect these signals, nor 
does disconnecting my Airspy HF+ from the IF Out jack.


Any idea what these might be?  Because they are discrete frequencies and 
relatively weak, they aren't particularly an operational problem, but


73, Pete N4ZR
Check out the Reverse Beacon Network
at , now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

.
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