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Nasty spurs on RX with new KPA500

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NC3Z Gary

Nasty spurs on RX with new KPA500

SN 3759 just received 2 days ago (kit form) and put in operational the
station. TX is fine, issue is on RX. It puts out strong spurs on 20-6M
with 10M being the worst. Tested on live antennas and dummy loads,
grounds on and off, all ancillary connectors removed, etc. So far this
is making the use of the upper bands very difficult. Now I know the
KPA500 has been around for a good amount of time so it cant be a design
issue.

I have a message into Elecraft but it's the weekend and wanted to just
run I by the groups to see if there are any ideas, as I mentioned it was
a kit, so I may have messed something up? But one big of diagnosis was I
turned off the backlight display and it reduced the spurs tremendously.

Hopefully this is a one off issue and it can be resolved.

Here is a video of what I am seeing: https://youtu.be/63fEFb3qIqM

--

Gary Mitchelson
NC3Z/4 Pamlico County, NC FM15
NC AHIMT COML
SHARES NCS997
NC Deputy Auxcomm Coordinator - Statewide
www.mitchelson.org

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Bob McGraw - K4TAX

Re: Nasty spurs on RX with new KPA500

Gary:

Nothing heard on my K3S that is being produced by my KPA500 {s/n 3519}
on 10M and nothing seen on my P3.

I would go back through each step of the assembly process and make sure
all is correct and all hardware is tight. I do see spikes from other
sources on 10M but these are in the order of -125 dBm. Nothing out of
the KPA500 in Operate mode that I can see or hear.

73

Bob, K4TAX

On 3/9/2019 5:36 AM, Gary NC3Z wrote:

> SN 3759 just received 2 days ago (kit form) and put in operational the
> station. TX is fine, issue is on RX. It puts out strong spurs on 20-6M
> with 10M being the worst. Tested on live antennas and dummy loads,
> grounds on and off, all ancillary connectors removed, etc. So far this
> is making the use of the upper bands very difficult. Now I know the
> KPA500 has been around for a good amount of time so it cant be a design
> issue.
>
> I have a message into Elecraft but it's the weekend and wanted to just
> run I by the groups to see if there are any ideas, as I mentioned it was
> a kit, so I may have messed something up? But one big of diagnosis was I
> turned off the backlight display and it reduced the spurs tremendously.
>
> Hopefully this is a one off issue and it can be resolved.
>
> Here is a video of what I am seeing: https://youtu.be/63fEFb3qIqM
>

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ANDY DURBIN

Nasty spurs on RX with new KPA500

In reply to this post by NC3Z Gary

Nothing heard or seen on 10 m with my kit built KPA500.

I'd suggest disconnecting the RX from the KPA500 and connecting it directly to the antenna. Does the problem go away?
If not, connect the RX directly to the dummy load. Does the problem go away?
If not, disconnect everything else from the KPA500 except the power cord. Does the problem go away?
If not, connect the KPA500 to an outlet on a different circuit. Does the problem go away?

Hopefully, one of these steps will give some information on the source of the problem.

73,
Andy, k3wyc

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Elecraft mailing list

Re: Nasty spurs on RX with new KPA500

A pound to a pinch of salt it's a poor connector.
David G3UNA

-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Andy Durbin
Sent: 09 March 2019 14:45
To: [hidden email]
Subject: [Elecraft] Nasty spurs on RX with new KPA500

Nothing heard or seen on 10 m with my kit built KPA500.

I'd suggest disconnecting the RX from the KPA500 and connecting it directly
to the antenna. Does the problem go away?
If not, connect the RX directly to the dummy load. Does the problem go
away?
If not, disconnect everything else from the KPA500 except the power cord.
Does the problem go away?
If not, connect the KPA500 to an outlet on a different circuit. Does the
problem go away?

Hopefully, one of these steps will give some information on the source of
the problem.

73,
Andy, k3wyc

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NC3Z Gary

Re: Nasty spurs on RX with new KPA500

In reply to this post by ANDY DURBIN

Connecting the RX directly to the antenna and the spurs are not there,
the spurs are coming from the KPA500, and only when the KPA500 is
connected to a radio (happens on all my radios connected to the KPA).
Have tried the amp on 220 and 120, same issue. The KPA500 can be
connected to a dummy load at the RF Out, and RF In to the RX and the
spurs are there. With out a doubt they are being generated in the KPA500
when the LCD backlight is on, and these are healthy spurs.

I have spent hours taking the thing apart and putting back with the same
results. Tripled checked all assembly with no luck. But I am 100%
positive it is directly related to the LCD backlighting. This is a very
weird issue!

Gary Mitchelson
NC3Z/4 Pamlico County, NC FM15
NC AHIMT COML
SHARES NCS997
NC Deputy Auxcomm Coordinator - Statewide
www.mitchelson.org

On 3/9/2019 09:45, Andy Durbin wrote:

> Nothing heard or seen on 10 m with my kit built KPA500.
>
> I'd suggest disconnecting the RX from the KPA500 and connecting it directly to the antenna. Does the problem go away?
> If not, connect the RX directly to the dummy load. Does the problem go away?
> If not, disconnect everything else from the KPA500 except the power cord. Does the problem go away?
> If not, connect the KPA500 to an outlet on a different circuit. Does the problem go away?
>
> Hopefully, one of these steps will give some information on the source of the problem.
>
> 73,
> Andy, k3wyc
>
>
>
>
>
>

ANDY DURBIN

Re: Nasty spurs on RX with new KPA500

In reply to this post by ANDY DURBIN

"Connecting the RX directly to the antenna and the spurs are not there,.."

That seems to suggest that the signal is coupling through the T/R switch. What happens if you key the KPA500 by grounding the key line input but leave the transceiver in RX mode? (Need to be in OPER mode). Look for the * on the left side of the KPA500 LCD to confirm keying.

Just to be clear - this is not a transmit test, just changing the state of the T/R switch in the KPA500.

Another test - leave the RX on 10 m and cycle through the KPA500 band selections using the KPA500 band switches. Is there any change in amplitude of the spurs?

73,
Andy, k3wyc

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ANDY DURBIN

Re: Nasty spurs on RX with new KPA500

Should have asked this one too - Does switching between OPER and STBY change the amplitude of the spurs?

73,
Andy, k3wyc

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Elecraft mailing list

Re: Nasty spurs on RX with new KPA500

In reply to this post by NC3Z Gary

Gary;

By now I am sure you have checked all the ribbon cable connections and are sure they are plugged in properly.
This sounds like a problem that needs to be addressed by the tech support guys. Be sure to give them a call on Monday.

73!
Jack, W6FB

> On Mar 9, 2019, at 9:14 AM, Gary NC3Z <[hidden email]> wrote:
>
> Connecting the RX directly to the antenna and the spurs are not there,
> the spurs are coming from the KPA500, and only when the KPA500 is
> connected to a radio (happens on all my radios connected to the KPA).
> Have tried the amp on 220 and 120, same issue. The KPA500 can be
> connected to a dummy load at the RF Out, and RF In to the RX and the
> spurs are there. With out a doubt they are being generated in the KPA500
> when the LCD backlight is on, and these are healthy spurs.
>
> I have spent hours taking the thing apart and putting back with the same
> results. Tripled checked all assembly with no luck. But I am 100%
> positive it is directly related to the LCD backlighting. This is a very
> weird issue!
>
> Gary Mitchelson
> NC3Z/4 Pamlico County, NC FM15
> NC AHIMT COML
> SHARES NCS997
> NC Deputy Auxcomm Coordinator - Statewide
> www.mitchelson.org
>
> On 3/9/2019 09:45, Andy Durbin wrote:
>> Nothing heard or seen on 10 m with my kit built KPA500.
>>
>> I'd suggest disconnecting the RX from the KPA500 and connecting it directly to the antenna. Does the problem go away?
>> If not, connect the RX directly to the dummy load. Does the problem go away?
>> If not, disconnect everything else from the KPA500 except the power cord. Does the problem go away?
>> If not, connect the KPA500 to an outlet on a different circuit. Does the problem go away?
>>
>> Hopefully, one of these steps will give some information on the source of the problem.
>>
>> 73,
>> Andy, k3wyc
>>
>>
>>
>>
>>
>>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>
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NC3Z Gary

Re: Nasty spurs on RX with new KPA500

Yes all are checked. Today I undid the front panel and as I move it away
from the rest of the KPA500 the spurs drop, so it is coming from the
front panel. The spurs also change pattern when I set the different
levels of brightness.

But more interesting, when I searched the archives using "birdies" I
found a few reports of exactly the same issue I am having here, almost
verbatim. Some SN are 4xx while other were 2xxx and 3xxx. But
unfortunately no followup in the archive.

So will have to wait for Elecraft to respond to my submitted report. But
at least I have not been alone in this issue and it goes back a good ways.

Gary Mitchelson
NC3Z/4 Pamlico County, NC FM15
NC AHIMT COML
SHARES NCS997
NC Deputy Auxcomm Coordinator - Statewide
www.mitchelson.org

On 3/9/2019 13:44, Jack Brindle wrote:

> Gary;
>
> By now I am sure you have checked all the ribbon cable connections and are sure they are plugged in properly.
> This sounds like a problem that needs to be addressed by the tech support guys. Be sure to give them a call on Monday.
>
> 73!
> Jack, W6FB
>
>> On Mar 9, 2019, at 9:14 AM, Gary NC3Z <[hidden email]> wrote:
>>
>> Connecting the RX directly to the antenna and the spurs are not there,
>> the spurs are coming from the KPA500, and only when the KPA500 is
>> connected to a radio (happens on all my radios connected to the KPA).
>> Have tried the amp on 220 and 120, same issue. The KPA500 can be
>> connected to a dummy load at the RF Out, and RF In to the RX and the
>> spurs are there. With out a doubt they are being generated in the KPA500
>> when the LCD backlight is on, and these are healthy spurs.
>>
>> I have spent hours taking the thing apart and putting back with the same
>> results. Tripled checked all assembly with no luck. But I am 100%
>> positive it is directly related to the LCD backlighting. This is a very
>> weird issue!
>>
>> Gary Mitchelson
>> NC3Z/4 Pamlico County, NC FM15
>> NC AHIMT COML
>> SHARES NCS997
>> NC Deputy Auxcomm Coordinator - Statewide
>> www.mitchelson.org
>>
>> On 3/9/2019 09:45, Andy Durbin wrote:
>>> Nothing heard or seen on 10 m with my kit built KPA500.
>>>
>>> I'd suggest disconnecting the RX from the KPA500 and connecting it directly to the antenna. Does the problem go away?
>>> If not, connect the RX directly to the dummy load. Does the problem go away?
>>> If not, disconnect everything else from the KPA500 except the power cord. Does the problem go away?
>>> If not, connect the KPA500 to an outlet on a different circuit. Does the problem go away?
>>>
>>> Hopefully, one of these steps will give some information on the source of the problem.
>>>
>>> 73,
>>> Andy, k3wyc
>>>
>>>
>>>
>>>
>>>
>>>
>> ______________________________________________________________
>> 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

Jim Brown-10

Re: Nasty spurs on RX with new KPA500

In reply to this post by Elecraft mailing list

Yes.

73, Jim K9YC

On 3/9/2019 8:09 AM, David Cutter via Elecraft wrote:
> A pound to a pinch of salt it's a poor connector.
>

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Jim Brown-10

Re: Nasty spurs on RX with new KPA500

In reply to this post by NC3Z Gary

On 3/9/2019 3:36 AM, Gary NC3Z wrote:
> It puts out strong spurs on 20-6M
> with 10M being the worst.

In addition to the possibility of a coax cable with a bad shield
connection, another thought -- is your station properly bonded? Every
chassis should be bonded together with short, fat copper, all equipment
should be powered from outlets that share the same "green wire" or
outlets whose green wires are bonded together. and bonds between those
outlets and all other grounds in your home.

73, Jim K9YC

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KD7PY

Re: Nasty spurs on RX with new KPA500

In reply to this post by NC3Z Gary

his is my post of Nov, 15 2011:

This is what I found as the source of the birdie's in the amp.

with the LCD BRT set anywhere from 1 to 8 the birdies are there.
with the LCD BRT set to DAY the birds are gone..

I have been working all day with Dale @ Elecraft with this and just sent him
a e-mail of what I found.
Dale has been very involved in this trying to track this down..

now we need to see just what kind of fix we can come up with..

I can't Thank Dale and crew enough for the support they have put into this,
as it appears everyone got envolved.

Thanks Again Dale @ crew..

Elecraft sent me a new Front board , as it is due to a bad filter cap on the
display driver

Ed K7WIA

--
Sent from: http://elecraft.365791.n2.nabble.com/
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NC3Z Gary

Re: Nasty spurs on RX with new KPA500

In reply to this post by Jim Brown-10

Yes Jim, everything is bonded. All 120V and 240V AC goes through ICE
suppressors on a SPG, all shack equipment is bonded to that, etc. It's
not a bonding issue (I have read and followed your "cook book" long
ago). Several direct e-mails indicate it's an issue with the front panel
board and this is not the first of this exact issue. So right now am
just waiting for Elecraft to open back on Monday.

Gary Mitchelson
NC3Z/4 Pamlico County, NC FM15
NC AHIMT COML
SHARES NCS997
NC Deputy Auxcomm Coordinator - Statewide
www.mitchelson.org

On 3/9/2019 15:47, Jim Brown wrote:

> On 3/9/2019 3:36 AM, Gary NC3Z wrote:
>> It puts out strong spurs on 20-6M
>> with 10M being the worst.
>
> In addition to the possibility of a coax cable with a bad shield
> connection, another thought -- is your station properly bonded? Every
> chassis should be bonded together with short, fat copper, all
> equipment should be powered from outlets that share the same "green
> wire" or outlets whose green wires are bonded together. and bonds
> between those outlets and all other grounds in your home.
>
> 73, Jim K9YC
>
>

NC3Z Gary

Re: Nasty spurs on RX with new KPA500

In reply to this post by Elecraft mailing list

Just a follow up to what Elecraft found on my new KPA500 that had spurs
on RX, which I sent back to them since the replacement front panel did
not fix the issue. Elecraft did indeed see the problem and said it was
pretty bad. They replaced the filter cap in the +5V supply that went to
the LPF, and added additional filter caps to the front panel. Any
remaining spurs are now below spec.

I was at least happy Elecraft saw the issue, as I had several responses
(direct) to my initial report on the reflector here that I did not know
what I was talking about and what I described could not happen.

Gary Mitchelson
NC3Z/4 Pamlico County, NC FM15
NC AHIMT COML
SHARES NCS997
NC Deputy Auxcomm Coordinator - Statewide
www.mitchelson.org

On 3/9/2019 13:44, Jack Brindle wrote:

>
>> On Mar 9, 2019, at 9:14 AM, Gary NC3Z <[hidden email]> wrote:
>>
>> Connecting the RX directly to the antenna and the spurs are not there,
>> the spurs are coming from the KPA500, and only when the KPA500 is
>> connected to a radio (happens on all my radios connected to the KPA).
>> Have tried the amp on 220 and 120, same issue. The KPA500 can be
>> connected to a dummy load at the RF Out, and RF In to the RX and the
>> spurs are there. With out a doubt they are being generated in the KPA500
>> when the LCD backlight is on, and these are healthy spurs.
>>
>> I have spent hours taking the thing apart and putting back with the same
>> results. Tripled checked all assembly with no luck. But I am 100%
>> positive it is directly related to the LCD backlighting. This is a very
>> weird issue!
>>
>> Gary Mitchelson
>> NC3Z/4 Pamlico County, NC FM15
>> NC AHIMT COML
>> SHARES NCS997
>> NC Deputy Auxcomm Coordinator - Statewide
>> www.mitchelson.org
>>
>>

Wes Stewart-2

Re: Nasty spurs on RX with new KPA500

Welcome to my club. Several times I have been in the same boat. The faithful
are wont to defend Elecraft equipment no matter what. Unfortunately, Elecraft
Support has done the same and more than once I've had to record little videos to
prove my observations.

Wes N7WS

On 3/29/2019 2:09 PM, Gary NC3Z wrote:

> ...
>
> I was at least happy Elecraft saw the issue, as I had several responses
> (direct) to my initial report on the reflector here that I did not know
> what I was talking about and what I described could not happen.
>
> Gary Mitchelson
> NC3Z/4 Pamlico County, NC FM15
> NC AHIMT COML
> SHARES NCS997
> NC Deputy Auxcomm Coordinator - Statewide
> www.mitchelson.org
>

Bill-4

Re: Nasty spurs on RX with new KPA500

Welcome to the club or been there and done that!!! There is a need for
thick skin here and that is too bad. You should be able to ask questions
and receive civil answers.

I have never received anything other than professionalism and expertise
from Elecraft, however.

Bill W2BLC

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Bill K9YEQ

Re: Nasty spurs on RX with new KPA500

Spurs can emanate from devices picking up high power signals and rectifying to create harmonics. I am not an expert but suggest either a review of handbook topics, or perhaps someone will help you troubleshoot from this list. You might also do a search on line for topics. Personally , I have had a KPA500 and 1500 and don't have the issue. However, each of us has a different setup. I don't think you have to have thick skin or think you aren't in a club here. There are a few who hover over us. Be patient and get the info you need to fix the issue.

Step one, do you have a dummy load? Even if it is only 100 Watt unit, reduce power from KPA500 and remove all connections except those that are needed to operate. On whatever piece of equipment you are using to detect the spurs, do you still see them? Someone will get back to you.

73,
Bill
K9YEQ

https://wrj-tech.com/

-----Original Message-----
From: [hidden email] <[hidden email]> On Behalf Of Bill
Sent: Friday, March 29, 2019 7:11 PM
To: [hidden email]
Subject: Re: [Elecraft] Nasty spurs on RX with new KPA500

Welcome to the club or been there and done that!!! There is a need for thick skin here and that is too bad. You should be able to ask questions and receive civil answers.

I have never received anything other than professionalism and expertise from Elecraft, however.

Bill W2BLC

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WW3S

Re: Nasty spurs on RX with new KPA500

He already stated, there was a problem with the amp....sent it in....elecraft fixed...

Sent from my iPad

> On Mar 29, 2019, at 8:22 PM, Bill Johnson <[hidden email]> wrote:
>
> Spurs can emanate from devices picking up high power signals and rectifying to create harmonics. I am not an expert but suggest either a review of handbook topics, or perhaps someone will help you troubleshoot from this list. You might also do a search on line for topics. Personally , I have had a KPA500 and 1500 and don't have the issue. However, each of us has a different setup. I don't think you have to have thick skin or think you aren't in a club here. There are a few who hover over us. Be patient and get the info you need to fix the issue.
>
> Step one, do you have a dummy load? Even if it is only 100 Watt unit, reduce power from KPA500 and remove all connections except those that are needed to operate. On whatever piece of equipment you are using to detect the spurs, do you still see them? Someone will get back to you.
>
> 73,
> Bill
> K9YEQ
>
> https://wrj-tech.com/
>
> -----Original Message-----
> From: [hidden email] <[hidden email]> On Behalf Of Bill
> Sent: Friday, March 29, 2019 7:11 PM
> To: [hidden email]
> Subject: Re: [Elecraft] Nasty spurs on RX with new KPA500
>
> Welcome to the club or been there and done that!!! There is a need for thick skin here and that is too bad. You should be able to ask questions and receive civil answers.
>
> I have never received anything other than professionalism and expertise from Elecraft, however.
>
> Bill W2BLC
>
> ______________________________________________________________
> 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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