KX3 Opposite Sideband Null -- Follow Up

[Grant Youngman-2]

Six weeks or so ago, I put up a couple of posts asking if anyone had had an issue with opposite sideband null on their KX3.  I was having a problem getting a good null when FL3 was selected, although I had very deep nulls with FL2 or FL1.  I wasn’t motivated to check because of a perceived problem.  I had simply decided to rerun the null procedure on a “just because” basis, for the same reason any radio I own ends up on the bench periodically for a checkup and alignment. I didn’t get any response from the list, so I presume this isn’t something most have rechecked.

In any case, Elecraft support suggested my results indicated a defective KXFL3.  After receiving and very carefully installing a new one, sure ’nuf.  All is fine now.  My subjective impression is that tuning around with narrow CW sounds “cleaner” since I have a good null on all bands and all filter settings.

I don’t really know if the original KXFL3 was DOA (although it was no doubt checked by Elecraft prior to shipment), if it suffered a random or infant failure, or if I was careless with the KXFL3 board while doing the initial kit build a few years ago.  Could certainly and perhaps most likely have been the latter.

Calibration is probably worth doing once in a while anyway.  Components age and drift, and, no matter what, things just happen.

And I did get excellent support from Elecraft while working through the problem.

Grant NQ5T


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Hi,I got several error codes on my KX3 about a year ago. I sent it back for repairs and upgrades as it is 0250+ s/n. Most error codes were cause by the defective ribbon cable between the front and rear boards. One code was a cracked resistor on the KXFL3. Repairs were done quick and got a complete retest and upgrades. Sure works better now. 73Jim H K7SSS In a message dated 7/18/2020 9:24:19 PM Pacific Standard Time, [hidden email] writes: 
Six weeks or so ago, I put up a couple of posts asking if anyone had had an issue with opposite sideband null on their KX3.  I was having a problem getting a good null when FL3 was selected, although I had very deep nulls with FL2 or FL1.  I wasn’t motivated to check because of a perceived problem.  I had simply decided to rerun the null procedure on a “just because” basis, for the same reason any radio I own ends up on the bench periodically for a checkup and alignment. I didn’t get any response from the list, so I presume this isn’t something most have rechecked. In any case, Elecraft support suggested my results indicated a defective KXFL3.  After receiving and very carefully installing a new one, sure ’nuf.  All is fine now.  My subjective impression is that tuning around with narrow CW sounds “cleaner” since I have a good null on all bands and all filter settings. I don’t really know if the original KXFL3 was DOA (although it was no doubt checked by Elecraft prior to shipment), if it suffered a random or infant failure, or if I was careless with the KXFL3 board while doing the initial kit build a few years ago.  Could certainly and perhaps most likely have been the latter. Calibration is probably worth doing once in a while anyway.  Components age and drift, and, no matter what, things just happen. And I did get excellent support from Elecraft while working through the problem. Grant NQ5T  
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