[Elecraft] KX1 rehab

[Don Wilhelm]

Bill,

Dale gave a good answer, but did not include how to do it with the KX1. 
I can supply that.

If you have the KXAT1 installed, pull it out and jumper between pins 1 
and 3 of the 3 pin header next to the BNC jack.  That connects the 
antenna with the KXAT1 not in place.

If you have a wideband noise generator, connect it to the BNC jack - if 
not you can likely use an antenna - tune to a spot where there is only 
band noise and set the RF Gain to max clockwise and the bandwidth to a 
mid-point.
Select 20 meters and tune CA and CB (marked 20A and 20B on the board) 
for a noise peak.  If you cannot discern a peak, try it tuned to a 
moderate strength signal.

Then, switch to 40 meters and peak CC (marked 40) the same way.

If you have 30 meters, switch to that band and adjust the 2 trimmers on 
the 30 (or 30/80) meter band board for a peak (30A and 30B).

Receiver alignment is done.

There is not much transmit alignment to do, but if the power output is 
not up to par on 20 meters, try changing the turns spacing on L2 - 
occasionally L1 as well.  These are the Low Pass Filter toroids.  Yellow 
cores unless the KXB3080 is installed and then they are red.  Work with 
the green windings on L1 and L2 if you have the KXB3080.  You usually 
spread the turns a bit, but sometimes squeezing them helps.

So much for the receive and transmit alignment of the base KX1.  Now you 
can put the KAT1 back in and balance the wattmeter.

Connect a good 50 ohm dummy load and set the ATU menu to CAL.
Get your DMM out and set it to read a low DC voltage.
Connect the negative lead to a ground - the 3/16 inch standoff on the 
battery connector end is my choice - use a clip lead on the meter lead.
Find an insulated tuning tool that will fit the slot of the capacitor on 
the KXAT1 board.
Put the positive meter lead on the test point next to the REFL 
potentiometer.
Do a TUNE and adjust the trimmer capacitor for a null - at least in the 
low millivolt range if it does not go all the way to zero.

If you have a well calibrated QRP wattmeter or other means of measuring 
power below 5 watts, install it between the KX1 and the dummy load.
Do a TUNE and observe the power on the wattmeter an also on the KX1 
display.  Adjust the FWD potentiometer until they read the same.

If you do not have an accurate wattmeter, observe that there are two 
black dots on the rotor of the potentiometer and a line on the stator. 
Put the two dots on either side of the line and call it good.
Set the dots of the REFL potentiometer the same way unless you have a 
good dummy load of 25 or 100 ohms, in which case, adjust for a displayed 
SWR of 2.0 when that load is connected.

Go to the ATU menu and set it to TUN.

Close up the back cover of the KX1, you are finished inside.

Now you can set the other menu parameters dealing with calibration.
These are well written in the manual.
BFO is first.  Best done by tuning to a known frequency AM station.  If 
your KX1 has 30 meters, use 10 MHz WWV  Ignore the exact KX1 frequency 
display (it will be close) and tune first in LSB to a clear tone or 
announcement voice, and write down the frequency displayed.
Then switch to USB and tune again for either the voice or the 500 or 600 
Hz tone if you have perfect pitch - write down the displayed frequency.
Subtract the LSB number from the USB number and record if the number is 
positive or negative.  See page 68 of the KX1 manual for the full procedure.
After the BFO Calibation, do the DDS Calibration as indicated on page 68 
of the manual.

You may now adjust the SIG parameters of the menu.  See the menu entry 
on page 65 of the manual.  Put the KX1 into DISPLAY with no signal input 
and adjust the LO parameter so there are no bars indicated.  You will 
have to exit the menu each time to observe.  Start with 1 more bars 
displayed and reduce the LO parameter by two until you see no bars. 
Sometimes you can see the lower bar flicker dimly (do not count that as 
a displayed bar).  Then try going up one number to see if you get a bar 
displayed - if not, leave it alone.
To set the HI parameter you will need a signal source that produces a 
known level signal of S-9 or S-9+20.  Adjust as indicated in the menu 
listing for 5 bars with an S-9 signal or 6 with an S-9+20dB signal.

That is it for the KX1 alignment.

73,
Don W3FPR





On 9/23/2017 3:38 PM, bill - K7WXW wrote:
> 
> Intent? Good question. Mostly I am wanting to tune the rig so it runs as it should but I also want to know how it works and learn how to do the stuff you mention in your list.
> 
> I am teaching myself how to do things like align a radio and checking specs.  As I haven't found anyone local with the time or interest in being a mentor, I am really happy to have email lists like this one!
>