KPA 500 birdies

[Stuart Dunk]

G'day all.
I have a KPA 500 Sn 423 and have discovered birdies every 10khz or so on 20 thru 6m, worst on 10m indicating about 1 s point on the ft1000 mk v field.
I have checked for external sources, earth loops, wall warts etc.
The noise is present when there is something plugged into the output of the amp, I use the term something plugged into the output because no matter what , antenna or coax patch cable or dummy load as soon as it is connected to the amp output the noise starts.

I have made up a sniffer antenna to hook up to the output to check various positions in the shack but the intensity of the noise will not change.
I have checked all the internal connections in the amp all the screws are tight and dimming the LCD makes no difference.
Has any one come across this in their amp if so did you find a fix.

Regards
Stu
VK4SDD
--
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.

______________________________________________________________
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

[KD7PY]

Contact Dale at Elecraft support...    I had the same problem and it turned out to be a bad cap on the board behind the front panel.  they sent me a replacement board right away.

A way to check it is go into the menu on the KPA500   set the LED BRT  to DAY and see if the birdies go away.  if so it is a bad board,    the birdies are only present when the LED BRT is set to anything but DAY..

it has something to do with the driver for the display......

Ed  K7WIA

[KD7PY]

OOPS   that should be LCD BRT  ( not LED )

[Don Wilhelm-4]

Steve,
  I just cannot unserstand how the KPA500 can create birdies during
periods of receive.
I would you suggest that you look for other potential problem sources
such as loose PL-259 connectors.

73,
Don W3FPR

n 1/28/2012 8:44 PM, Stuart Dunk wrote:

> G'day all.
> I have a KPA 500 Sn 423 and have discovered birdies every 10khz or so on 20 thru 6m, worst on 10m indicating about 1 s point on the ft1000 mk v field.
> I have checked for external sources, earth loops, wall warts etc.
> The noise is present when there is something plugged into the output of the amp, I use the term something plugged into the output because no matter what , antenna or coax patch cable or dummy load as soon as it is connected to the amp output the noise starts.
>
> I have made up a sniffer antenna to hook up to the output to check various positions in the shack but the intensity of the noise will not change.
> I have checked all the internal connections in the amp all the screws are tight and dimming the LCD makes no difference.
> Has any one come across this in their amp if so did you find a fix.
>
> Regards
> Stu
> VK4SDD

______________________________________________________________
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]

On 1/28/2012 7:30 PM, Don Wilhelm wrote:
> I just cannot unserstand how the KPA500 can create birdies during
> periods of receive.

Don,

When thinking about sources of RF trash, remember that ANY oscillator or
microprocessor or any other piece of digital circuitry generates RF
trash as a byproduct of its operation, and must be contained by good
circuit design.  That includes careful layout to minimize current loops
and wires that can radiate, as well as avoiding Pin One Problems.

 From the symptoms (the bad cap and the LCD Brightness), it sounds like  
something associated with the display circuitry is the culprit. FWIW,
I've heard it with my KPA500.

73, Jim K9YC
______________________________________________________________
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