[Elecraft] K3: KRX3 hearing no Signals

[Ed Gray W0SD]

For future reference for people searching as to why there KRX3 is not 
hearing any signals be sure the filters are installed in the slots they 
are supposed to be.  You will have noise and the sub controls will work 
but you are not hearing any signals.  I know what I am going to write 
sounds simplistic but read on there is more to it than one would think. 
  I am well aware of filter placement as I have put together two K3's 
and as I was putting the KRX3 together my XYL Edith W0OE mentioned the 
manual information that the widest filter needs to be first.  It does 
not have to be in FL1 but it has to be first.  I told her "THANKS I AM 
AWARE OF THAT"!  How I did it I will never know but I proceeded to start 
with the wide filter in FL5 and then FL4, FL3, FL2 leaving FL1 open. 
Somehow in turning the board back and forth I messed up.

What makes this more tricky than the filters on the main board of the 
K3?  First of course the top shield soon covers your mistake.  Secondly 
what make it even more tricky with the KRX3 the K3 only checks for 
correct filter placement in the main rig for the FLTX settings that 
affect the transmitter and mode (ERR TXF for example). In the SUB, it is 
solely up to you to get them right.

Thirdly what really fooled me was I used the K3 utility and made changes 
to the KRX3 filters and changed things on FL1 in the KRX3 and sent them 
to the radio.  I also set the filters up from the CONFIG setting so 
everything appears to be fine but in fact there was no filter at all in 
FL1 so the "ONLY" way to figure it out is to visually look at the filter 
placements.  That is the only way to find this mistake in the KRX3 other 
than starting to trace the rcv signal which I was about ready to to. BTW 
Elecraft support has an excellent test procedure for this. The good news 
is when I pulled the top shield off I spotted the wrong filter placement 
instantly and just could not believe I made a stupid mistake like that. 
I took 4.5 hours with a break to put the KRX3 together and still made 
the mistake!  I think when you know something you can easily become 
careless.

I also got ERR VC4  E 00039 which required an adjustment of T1 windings 
on the sub synth board.  Don't do this without instructions on how to do 
it. That problem was not my fault.  It is just one of those things and 
was a real easy fix.

Others have commented on the front panel removal!  I concur it is not a 
big deal.  The only thing that I would emphasize is when you put in the 
BNC for the Aux RF to note the instruction about "NOT" taking out the 
one screw. I dropped the stand off down in the radio and it took a lot 
of messing to get it out!!!

After having the KRX3 board with the shield on in and out of the radio 
more times than I care to mention you eventually find you can get the 
cables routed quite nicely out of the way.  At first it does not seem so 
but keep adjusting things as the cables can be placed so it comes in and 
out easily.

BTW I was reading the KDVR3 manual and the front panel steps are 
basically the same as the KRX3 removal of the front panel.

What a mad rush to get things working with the KRX3 on Thursday and then 
working right up until the 160 meter contest to get the two new 
bi-directional beverages hooked up and get everything interfaced to the 
K3 and try and learn how to use the RX antenna "AND" the sub-rcv "AND" 
diversity and provide some additional protection from RF getting into 
the radio.  We had a whole 30 minutes to spare!  Joe W0DB is operating 
here at W0SD and he has a lot of choices.  It is so impressive what the 
K3 with the sub and with all the filters can do.  The noise blanker also 
works the best of anything I have every used.  The two best previously 
was the TR-4 years ago when mobile and the FT-1000B.  Not only does it 
take out the noise it handles the strong signals with ease!!!  I never 
seen anything like it.   In this case for CW we are using the 500 hz and 
200 hz on the main board and on the sub.  Joe was down to 50 hz with the 
DSP and we still had QRM.  Given I am told 50 hz is about the best you 
can do with your head the QRM on 160 meters in the contest is something 
to behold!!!  I have had Collins line, Drake Line, ICOM, FT-1000D, 
TS-950SDX, etc.  This is truly the greatest radio I have ever owned. 
With the KRX3 installed and the KXV3 the flexibility for antenna 
switching and diversity reception of signals is something not found 
anywhere.  We have a switch so we can use the 7 rcv antennas either as 
rcv antennas to the RX in on the KXV3 or we can use them on the AUX RF 
in for the sub or sub using diversity.  There are other ideas we have 
but this is all we had time for getting everything going.

Ed W0SD