[Elecraft] 10Mhz alignment

Thu Oct 10 13:35:01 2002

Hi

First I would check the calibration on the counter. You are only off 3.4 =
parts per million and many counters are not that good unless they have a =
TCXO. You can check the counter by listening to the counters 10 mhz clock=
 and WWV at the same time on your K2 and adjust the counters time base fo=
r zero beat. I have done this with a Tektronix time mark generator and it=
 works great. You may need to connect a loop of wire to the K2 so you can=
 pick up the counters time base. Anyway this will put your counter right =
on frequency so you can set up your K2. Because the two frequencies beat =
with each other, the calibration of the K2 is not a factor for this set u=
p. Just adjust the K2 so you hear WWV's carrier at about 600 hz and adjus=
t the counter to zero beat. It's sounds just like zero beating with the s=
pot tone.

I like a different way to calibrate a K2. Set up your K2 to receive WWV a=
nd connect up a computer running spectrogram. Set up a reference mark at =
500 and 600 hz on the computer. On alternating minutes WWV will transmit =
a tone of 500 and 600 hertz audio. This is not on all minutes so you may =
need to wait a few minutes for the tones. You will see a spike on the ban=
dpass. Adjust the VFO so the spike is over the correct marker. Wait for t=
he next minute when the frequency changes to verify you are on the right =
frequency. Now check the K2 readout to see how much you are off. Connect =
the K2's counter probe to TP2 and read the frequency (don't touch the VFO=
 nob). Adjust C22 on the control board to correct the frequency by the sa=
me amount as the VFO is off. An example if the VFO is 20 hz high then low=
er the frequency at TP2 by 20 hz. Then run CAL PLL to do the calibration.=
 Recheck WWV as above. This will put your K2 right on frequency. =20

While you have spectrogram running check the filter setting also. =20

I have used this method to calibrate many K2's and its the best I have fo=
und

Don Brown
KD5NDB

5 K2's
3 K1's
all options many times
4 KPA100's
KPA100 and KAT150 field tester

----- Original Message -----
From: [email protected]
Sent: Thursday, October 10, 2002 11:24 AM
To: [email protected]
Subject: [Elecraft] 10Mhz alignment

According to my Leader LDC-824S counter, when transmitting with an =20
indicated dial freq of 10.000.00Mhz, (Tune mode at .1w) my K2 is
actually TX on 9.999966

Tuning in the reference freq of the counter on the K2, I _almost_ =20
zero-beat at 10.000.04Mhz.  When I TX with an indicated dial freq =20
of 10.000.04Mhz, the counter reads it as 10.000001.

So, with such a small error, is it worth the trouble to try and get
closer?

I tested this because It seems that to have people sound right on 18.132,
I tend to tune to 18.132.10 and nobody tells me that it sounds like I'm
off freq (high).

TX with an indicated dial freq of 18.132.00, the counter sees 18.132399.

All counter readings taken with a 10s gate time for better accuracy.

Am I just being anal/paranoid or could I get this closer?

73 de John - KC4KGU
K2/100 #2490

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