Testing for Frequency Drift using ARGO Frequency Measuring Software
Go K0TO web site for Checking and Setting the Frequency of the FT1000MP REF oscillator and Temperature Stabilized FT1000MP REF oscillator which contains more information and graphics on this issue. (Updated May 4th, 2003)
A number of folks have asked about the ARGO frequency measuring software. Here is the URL to the site which has the downloadable program: http://www.weaksignals.com/argo You will need to connect the FT1000 AF out port to the LINE IN port on a sound card via a direct connection. No transformers are needed since you will be receiving not transmitting.To check your radio's frequency and stability do the following:
enter 10.000.00 into VFO A. Be sure that you set the VFO so that
frequency is exactly 10.000000 MHZ down to the single HZ. Read your
2. Set VFO B = VFO A.
3. Tune VFO A to 10.000.50 and select USB or LSB so that you hear the carrier tone of 500 Hz. (I am traveling and forgot if it was USB or LSB that will give the tone at 10.000.50 -- but one or the other will, probably LSB.)
VFO A and VFO B. Set VFO A to 09.999.50 on the dial and select the Mode
(probably USB) that allows you to hear the 500Hz carrier. Now you
5. Switch back
and forth between VFO A and VFO B. If your ref oscillator is set for the
correct frequency the tone will be the SAME no matter which VFO
6. Start up
the ARGO program and using the help screens set up the parameters for
your sound card. The Mode should be set at 3s dots and the Speed should
be normal. Click the Start Button in the lower right hand corner and you
will see a waterfall display. Look for a line at about 500 Hz and click
on the line. The trace will move horizontally across the screen from
right to left and the frequency will be shown at the top of the chart
and at the right side. When you switch from VFO A to VFO B the frequency
will change (unless you happen to be right on the reference frequency).
Add the frequencies shown for VFO A and VFO B together and divide the
sum by two. Subtract 500 from the result and you have a measure (in Hz)
of how far off of the correct reference frequency your radio is. (Note:
If your radio is 'right on' you will have added 500+500 to get 1000 and
divided by 2 for a result of 500. When you subtract five hundred from
that you get zero which
7. Turn off the radio and stop the ARGO display (button at bottom right). Let the radio cool for ten or 15 minutes. Turn on the ARGO display after cooling the radio and the turn on the radio. You should be able to see the reference frequency come back to the original value you measures. It may take some time. Take readings and write them down. Make a couple of runs this way to get a good idea of what the frequency error of your radio is. If you make a reading every minute you can get an idea of the drift in Hz per minute.
I will advise reflector readers when I have additional information on my web site (probably at least a couple of days). If anyone does these measurements and wants to share their results I would be interested simply to see what the variability between radios happens to be. You can send results directly to me or put them on the reflector == your call.
Tod, KØTO http://www.k0to.us/
I have posted two JPEG files which show the ARGO measurements for the first 90 sec after turning the radio on (cold start.jpg) and after 90 minutes of operation (long term.jpg). They can be found at http://www.k0to.us/
I have posted additional pictures of the ref oscillator mod that I made at www.k0to.us . The pictures have links in the table following the home page picture. The four pictures showing the reference oscillator board and the modifications are DSCN4434,DSCN4435, DSCN4442 and DSCN4443. The thermistor-resistor circuit is one that uses a 25V50/50C positive temperature coefficient thermistor, (Mouser part # 527-3006-25V50/50C about $2.28) in series with a 1/4 watt 68 ohm resistor connected between ground and the +9 volts on the board. One lead of the thermistor is soldered to the case of the crystal and from there to ground. The other lead of the thermistor goes to the 68 ohm resistor which has its other end connected to +9 volts. The thermistor should be physically touching the crystal case to assure good heat transfer. Remove the board before working on it. Scrape the metal case in a thin line so that you can put a bead of solder on the case (20 watt iron is plenty hot). Then solder the thermistor lead to the case along the solder line. Dress the ground lead to the bottom of the board per the picture. Connect the 68 ohm resistor to the +9 volt point shown on the picture. Use insulated tubing to protect the leads from shorting.