KX3 mode PSK D problem

[N5XL]

Guys...HELP!!!  I am having trouble with my KX3 and mode PSK D (PSK31).  

When I attempt to use the KX3 only to generate PSK31 signals (that is no computer interface…strictly the KX3 with the iambic paddle), I either do not get any measurable RF output or, I do not get any stable RF output.  

Setting the KX3 to mode PSK D and setting RF power to 5 or 10 watts and attempting to initiate a PSK31 transmission with iambic paddles, the KX3 initially shows a quick RF power indication that immediately drops to 1 bar indicated on the KX3 meter (should show 5 bars or 10 bars depending on the power setting).  The no RF power output condition is verified using an inline peak reading wattmeter attached to a 50 ohm dummy load. I can see the initial RF power spike that drops to 0 watts on the external wattmeter.  Even though there is no power indicated, I can hear weak PSK31 audio being generated when listening with a secondary receiver (ICOM R75) tuned to the KX3 transmit frequency.

Adjusting the RF power knob while in PSK D transmit mode (sending the letter “e” with the iambic paddle every 2 seconds) the KX3 will eventually show some RF power being generated but RF power does not appear stable.  Power indicated on the KX3 and power indicated on the external wattmeter does not match the RF power setting of the KX3.  

Listening to the KX3’s signal with the ICOM receiver shows the same erratic power output (no S meter reading that jumps to S9+20 when dialing the power DOWN on the KX3).  Pops and clicks can be also be heard on the ICOM when adjusting the power knob of the KX3.

Here is the kicker…all other modes on the KX3 appear to work normally, including the internally generated FSK D mode. Setting the KX3 to mode FSK D and initiating a transmission using the iambic paddles shows stable RF output that matches the KX3’s RF power setting.  Adjusting the RF power while in FSK D transmit shows smooth power progression from 0.1 watts to 12 watts and no audible clicks or pops are heard in the ICOM.

I was using 1.54 firmware but I’ve dialed back to the 1.48 official firmware with no improvement.  I have also bypassed the internal ATU with no improvement.

Is there any additional testing that anyone can think of before I send an email to the service department?

73,
Dave
N5XL

[Lyle Johnson]

Looking into it...

73,

Lyle KK7P

Sent from my iPad

On Aug 18, 2013, at 11:16 AM, N5XL <[hidden email]> wrote:

> Guys...HELP!!!  I am having trouble with my KX3 and mode PSK D (PSK31).  ...
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[wayne burdick]

Dave,

I can't duplicate this. I get the set power level throughout PSK-D transmissions.

Try redoing the TX gain calibration and let me know what you find.

73,

Wayne
N6KR



On Aug 18, 2013, at 11:16 AM, N5XL <[hidden email]> wrote:

> Setting the KX3 to mode PSK D and setting RF power to 5 or 10 watts and
> attempting to initiate a PSK31 transmission with iambic paddles, the KX3
> initially shows a quick RF power indication that immediately drops to 1 bar
> indicated on the KX3 meter (should show 5 bars or 10 bars depending on the
> power setting).



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[N5XL]

Thanks Wayne,

TX Gain Calibration competed with no change in regards to the PSK31 problem.  Also tried firmware 1.50 with no change either.

I have received some off the list suggestions that the PA may be folding back due to high temps but that is not the case.  The temp has not exceeded 35C for the on the bench testing that I am doing.

The problem was initially found when I was mountain top portable and tried to initiate a PSK31 contact at 3 watts.  With no luck at 3, I move to 5 watts and that is when I noticed the RF power meter of the KX3 not showing any output power.  At this point I knew something was wrong so I came home and started the bench testing.  

Strange that all other modes work perfectly, including internally generated RTTY.  Only internally generated PSK31 has this problem.

Any other ideas to try?

73
Dave
N5XL