K2 almost deaf on 40 meters only

[Stan AE7UT]

I just recently noticed I can barely hear S9 signals on my K2.
I checked with my XG3 and on all the other bands I get an S9 signal with the -73 dBm
level but on 40 it gives an S1 reading.

This is a K2 I bought 2nd hand while I'm building my own.
It has a DSP in it and as far as I can tell it has the same settings on all bands.

How would I go about diagnosing this problem?
It was working about a week ago.  This is my main CW machine.

Thanks
73 Stan AE7UT

[Mike K8CN]

Hi Stan,

You didn't indicate other options besides the DSP module that are installed in your K2,
but here are some possible gremlins in order of decreasing likelihood of being the culprit:

1) Check the ATT/PRE switch when on 40 meters to be sure the ATT is not switched on.

2a) If you have the KAT2 auto-tuner installed, check the ANT1/2 switch to be sure you
have not inadvertently selected the wrong antenna port for your 40 meter
antenna.

2b) Presuming that cause #2 is not the culprit, tune the auto-tuner while the K2 is on 40 meters and connected to a good 50 ohm dummy load.  Disconnect the dummy load and repeat the XG3 test.
(Alternatively, you could place the KAT2 into Bypass mode - see the KAT2 manual for details)

3) If you have the K160RX module installed, go into the MENU and select the RANT parameter
while you're on 40 meters - verify that RANT is "OFF".

4) Although very unlikely, one of the filter components or a relay in the 40 meter lowpass or bandpass filter sections may have a bad solder joint that finally was jostled loose in the last week.  You can follow the signal tracing directions in the K2 manual if you've exhausted possibilities #1 - #3 above and need to check for an actual physical disconnection on the RF board.

I'm curious to know of your findings......

73,
Mike, K8CN

[Don Wilhelm-4]

Stan,

Check the RX ANT setting in the menu.  That is a per-band setting. If
the RX ANT is set to ON for 40 meters, you will not hear much through
the normal antenna connection, but will hear a good signal through the
RX Ant jack.

If that is not the problem, ask again and tell us whether your K2 has
the K60XV option installed or not.

73,
Don W3FPR

On 7/11/2013 9:11 PM, Stan AE7UT wrote:
> I just recently noticed I can barely hear S9 signal on my K2.
> I checked with my XG3 and on all the other bands I get an S9 signal with the
> -73 dBm
> level but on 40 it gives an S1 reading.
>
> This is a K2 I bought 2nd hand while I'm building my own.
> It has a DSP in it and as far as I can tell it has the same settings on all
> bands.
>

______________________________________________________________
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

[Stan AE7UT]

Well you both had it spot on.
"Someone" came in my shack and turned the receive antenna on!
It's now working FB.

I sure learned a bunch about the DSP last night.  I stayed up until 3:00 AM
trying to figure out what in the world was wrong.  I changed every parameter
I could think of and just could not figure it out.
It took you guys what.... 3 seconds?

Thanks to both Mike K8CN and Don W3FPR for the fix.

73
Stan AE7UT