New KPA100 no receive on SO239

[Catherine James]

I have largely completed building my KPA100, and reached the point in testing where the speaker works if connected to the base K2 with the signal coming in through the BNC antenna port.

However, I have been unable to hear anything when the antenna is connected to the KPA100's SO239 antenna port.  On 40m, I had a strong signal coming in on a different receiver, but switching the same antenna to the K2/100 produced silence.  (Because of lack of signals on other bands lately, I cannot do a good receive test on other bands.  The K2 receiver is too quiet to use normal band noise for a good test!  I may have to create my own QRP signal from a different transmitter into a dummy load to have a signal to listen for.)

I have traced DC continuity from the RF Aux pin on the KPA100 board to TP2 and TP3. I have also traced DC continuity from the center pin of the SO239 to T4-6, T4-5, and C1.  I also appear to have DC continuity between L4, L5, and L6.

Are K5 and K6 latching relays?  Should I have DC continuity from RF Aux RFIN all the way to J2, going through the low-pass filter of the band most recently selected?  Or do K5 and K6 open on all bands when power is off?

What should I check next?

73,
Cathy
N5WVR
______________________________________________________________
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]

[Don Wilhelm-4]

Cathy,

You must have the ribbon cable connected.  With that connection and the
power turned on the base K2 (no power to the KPA100), you should have
continuity between the center of the KPA100 SO-239 jack and the center
conductor of the KPA100 board RF IN coax.
Yes, the KPA100 Low Pass Filter is in the path.  The base K2 12CTRL line
powers the relays as well as the MCU and other control circuits in the
KPA100.
The relays in the KAP100 are not latching type.
If you do not have continuity as described above, check the soldering.  
The KPA100 has a large copper ground plane area.  If you did not use a
soldering temperature of the recommended 800 degF, you may have
inadequately heated solder connections - reflow the soldering until you
see the solder flow out fully onto the solder pad and the component lead.

Do you have the center conductor of the coax header which plugs into the
base K2 correct?  The shield is closer to the K2 side panel than the
center conductor.
Check the insertion of the crimp pins of the J1 header to make sure they
are correct.  Looking into the rectangular holes in the header, you
should see the locking tabs latched behind the plastic, and you should
be able to wiggle the crimp pins slightly by pushing/pulling on the coax
wires.

73,
Don W3FPR

On 1/2/2016 5:10 PM, Catherine James wrote:

> I have largely completed building my KPA100, and reached the point in testing where the speaker works if connected to the base K2 with the signal coming in through the BNC antenna port.
>
> However, I have been unable to hear anything when the antenna is connected to the KPA100's SO239 antenna port.  On 40m, I had a strong signal coming in on a different receiver, but switching the same antenna to the K2/100 produced silence.  (Because of lack of signals on other bands lately, I cannot do a good receive test on other bands.  The K2 receiver is too quiet to use normal band noise for a good test!  I may have to create my own QRP signal from a different transmitter into a dummy load to have a signal to listen for.)
>
> I have traced DC continuity from the RF Aux pin on the KPA100 board to TP2 and TP3. I have also traced DC continuity from the center pin of the SO239 to T4-6, T4-5, and C1.  I also appear to have DC continuity between L4, L5, and L6.
>
> Are K5 and K6 latching relays?  Should I have DC continuity from RF Aux RFIN all the way to J2, going through the low-pass filter of the band most recently selected?  Or do K5 and K6 open on all bands when power is off?
>
> What should I check next?
>
> 73,
> Cathy
> N5WVR
> ______________________________________________________________
> 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
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]

[Catherine James]

I touched up  the solder contacts along the path that Don outlined, plugged in the ribbon cable and RF cable, powered on, and voila! had DC continuity. I can now hear RF signals from the antennas fed through the SO239.  Thank you!

The only issue now is that audio level is noticeably lower when headphones are plugged into the KPA100 speaker jack than when the same headphones are plugged into the audio jack on the front of the K2. All the calibration steps aren't done yet, so maybe this will be an easy tweak.

73,
Cathy
N5WVR

Sent from Yahoo Mail on Android

______________________________________________________________
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]

[Don Wilhelm-4]

Cathy,

Could the difference between the headphone output and the external
speaker jack be attributed to the fact that the headphone jack has both
channels (stereo) active while the external speaker is monaural?  In
other words, the external speaker jack will only activate the left side
of the headphones.

73,
Don W3FPR

On 1/2/2016 8:56 PM, Catherine James wrote:
>

______________________________________________________________
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]

[Catherine James]

Possible, but the audio level of the KPA100 speaker was also so low that I had to turn the audio up to full and put my ear next to the speaker to hear anything. I think there's still an issue here, but I'll play with it more and see what develops.

Sent from Yahoo Mail on Android

______________________________________________________________
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]

[Don Wilhelm-4]

Cathy,

There should not be that much of a difference.  The speaker should fill
a normal room with the AF gain at about 10 o'clock.
Check the polarity of the speaker wires.  If you interchanged the two
speaker leads, the speaker audio will be shorted out.
Pull the speaker housing out of the P5 header and measure the resistance
to the KPA100 ground of the cable.  You should measure zero ohms on the
side that is furthest away from the K2 side panel. The lead that will be
closest to the right side panel should measure the resistance of the
speaker voice coil, which should be 3 to 4 ohms.
In other words, if you swapped the silver and copper wires anywhere
along the paths, you would produce the results that you are hearing.

73,
Don W3FPR

On 1/2/2016 9:08 PM, Catherine James wrote:
>
> Possible, but the audio level of the KPA100 speaker was also so low
> that I had to turn the audio up to full and put my ear next to the
> speaker to hear anything. I think there's still an issue here, but
> I'll play with it more and see what develops.
>
>
>

______________________________________________________________
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]