[Lowfer] ARGO

[Douglas D. Williams]

Hi Mike. My method for calibrating ARGO is very simple, and does not
require any extra equipment. As someone else pointed out, first you have to
know the BFO sidetone of your receiver. Most modern receivers allow you to
vary this sidetone through some sort of menu. I happen to like to hear a
700Hz tone when listening to CW, so that's what I keep mine at. I tune to
60 kHz WWBV with the receiver set to CW mode (reverse CW for Icom
receivers), and allow the receiver to warm up for an hour. If you are using
an upconverter, then simply tune to the converter's LO frequency + 60 kHz,
so in my case that would be 3.060 MHz. At this point I would set Argo to
some relatively fast QRSS speed such as QRSS10, and center 700Hz on the
right side scale. You may have to reduce the receiver's audio gain and
lower Argo's sensitivity slider quite a bit because WWVB is very strong in
the lower 48. If your total system calibration is within 20Hz or so of
being correct, you should see a bold, thick line start scrolling across the
screen, with thinner lines (sidebands, I guess) above and below it. What
you want to do is go into Argo's setup menu and choose Calibration. If you
see the bold line at, say 705Hz then you would enter 700 (if that's the
sidetone you are using) in the Measured frequency box and 705 in the
Displayed frequency box. That should get you within one Hz of being dead
on. You can dial it in even more at the slower QRSS speeds by using decimal
places in the numbers you put in the Displayed frequency box.

What you are doing is calibrating the total receive system (receiver,
upconverter, computer sound card) to be correct on the Argo screen. Of
course, the job is easier if the oscillators in your receiver and
upconverter are close to the frequency they should be. If you are using an
upconverter with one of those little 4 MHz crystals about the size of a
child's fingernail, good luck. ;-)

At this point, many people go a step further because they like to have
Argo's frequency scale (the one on the right) display the actual frequency
(in Hz) that they have the receiver tuned to. This can be accomplished by
using the Offset box in the Calibration window and typing in the frequency
you have the receiver tuned to, minus your BFO frequency, if I remember
correctly. I'm usually too lazy to do this, so my screen captures tend to
 just have the BFO sidetone frequency.

Well, that was a lot of typing to describe something that generally only
takes about five minutes to do, once the receiver is warmed up. ;-)

73, Doug KB4OER

On Mon, Dec 31, 2012 at 1:58 PM, Mike Sanders <k0az at centurytel.net> wrote:

> Stan, Charlie and Mark, Thanks very much for all your input.
> I am going to continue to follow through with this until I get it.
> Your help may make the difference.
> I am also using a converter and it is introducing minus 302 hz
> of aggravation from the LO. My first lowfer target is WMS only
> about 170 miles South of me.
> I have not looked through all your email info yet but will as well
> as checking out John's write up on ARGO set up.
> Thanks again and you will know when I get a good capture.  73
>
> Happy New Year
> Mike Sanders
>       K0AZ
>
>
>
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