Re: KX3 receive discontinuity at 6.000 MHz

[Mike Morrow-3]

I believe my KX2 and your KX3 use almost identical BPF and LPF network switching breakpoints (not including the KX3 6m band):

BPF/LPF Span (MHz) Ham Bands (meters)
 Below   4.5       160, 80 (160 below  3.0)
 4.5 to  8.5        60, 40 ( 60 below  6.0)
 8.5 to 17.0        30, 20 ( 30 below 13.0)
17.0 to 23.0        17, 15 ( 17 below 19.0)
23.0 to 30.0        12, 10 ( 12 below 26.0)

Although no BPF or LPF switching occurs at 6.0 MHz, my KX2 band changes from 60m to 40m at that point and thus changes the KXAT2 ATU relay presets unless I have ATU MD in BYP.  That can cause signal strength changes at 6.0 MHz similar to what you report.  With ATU MD in AUTO, I get some signal drop at 6.0 MHz increasing.  With ATU MD in BYP, I get absolutely NO signal change at 6.0 MHz, increasing or decreasing.

The mystery is that you report the signal strength changes at 6.0 MHz even with the KXAT3 ATU MD in BYP.  I am at a loss.  There should be no relay operation in the KX2/3 at 6.0 MHz if the KXAT2/3 ATU MD is BYP.  Do you hear any relay operation at 6.0 MHz with ATU MD in BYP?

Mike / KK5F

-----Original Message-----

>From: Walter Underwood <[hidden email]>
>Sent: Nov 26, 2018 11:04 PM
>To: "Elecraft QTH.net List" <[hidden email]>
>Subject: [Elecraft] KX3 receive discontinuity at 6.000 MHz
>
>I was tuning in Radio Havana Cuba with my KX3 a few nights ago. I received them fine at 5999.999 kHz, but their signal and the background noise dropped way, way down when I tuned 6000.000 kHz. This happened with AM, USB, and LSB. It was also visible on my PX3. I bypassed the ATU, no change. Set the XPA100 to “not installed”, no change. Bypassed the ATU.X, no change.
>
>KX3 serial number 2985, latest firmware.
>
>Any clues? I’m tempted to do an EEINIT and reload the config, just on general principles.
>
>wunder
>K6WRU
>Walter Underwood

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