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




_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[AC7AC]

CONTENTS DELETED

The author has deleted this message.

[Dick Dievendorff]

I tried this on the K3 Utility, and the Field Test feedback was that the
right-to-left order was "weird".  So I just put in a note in Help that the
figures are right to left as viewed from the front of the K3.

The XFIL icons on the front panel are also left to right, which was further
support to putting the K3 Utility columns in a 1-5 order.

Dick, K6KR


-----Original Message-----
From: [hidden email]
[mailto:[hidden email]] On Behalf Of Ron D'Eau Claire
Sent: Saturday, December 06, 2008 1:46 PM
To: [hidden email]
Subject: RE: [Elecraft] K3: KRX3 hearing no Signals

Ed, W0SD, wrote:

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.

-------------------------------------------------------------------------

I suspect the root of the problem is that most of us are used to working
left to right, and the K3 filter layout in the rig is right to left.

Yours and other comments have me thinking that in the next update I'll
redesign the table so, instead of going down the rows FL1 through FL5, it'll
be laid out horizontally with FL1 at the *right* and FL5 at the left end,
just as they are laid out in the K3 and KRX3, with the bandwidths and
offsets on the rows under them.


Ron AC7AC


_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com

[Scott Prather-2]

This evening I finished installation of the KRX3 that I ordered back in
April, and I ran into a problem with poor sensitivity on the Aux port I
thought others might be interested in.

After I completed installation of the KRX3 and went through the requisite
VCO calibration, filter setup, etc., I found that the receiver worked
flawlessly on the main antenna, but sensitivity on the Aux port was poor
(about 30 dB below that of the Main antenna port). Thinking that I might
have a bad TMP cable from the KRX3 Aux port to the KAT3, I pulled the KRX3
out, removed the KRX3 circuit board from the shield, and used an ohmmeter to
confirm continuity. All was well. I reassembled the KRX3 and reinstalled it,
same problem. I then removed the top portion of the shield while the KRX3
remained in situ, and sensitivity on the Aux port was normal.

Spark arrestor, SA1, is mounted very close to the edge of the circuit board.
In my KRX3, this component has "leaning" towards the outside edge of the
board sufficiently to allow the top shield to short it to ground. Bending
the leads of SA1 just slightly so that it was away from the edge of the
board resolved the problem.

Scott
N7NB

_______________________________________________
Elecraft mailing list
Post to: [hidden email]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
 http://mailman.qth.net/mailman/listinfo/elecraft   

Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com