[Elecraft] KX3 receive discontinuity at 6.000 MHz

[Walter Underwood]

I watched the lights on the KXP100 carefully tonight and it was switching to ANT 2 at 6 MHz. In my shack, ANT 2 is connected to a dummy load.

I switched it to ANT 1 and Arnie Coro was coming in nicely both above and below 6 MHz.

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Nov 27, 2018, at 7:04 AM, Mike Morrow <kk5f at earthlink.net> wrote:
> 
> 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 <wunder at wunderwood.org>
>> Sent: Nov 26, 2018 11:04 PM
>> To: "Elecraft QTH.net List" <elecraft at mailman.qth.net>
>> 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