[Lowfer] Using Argo

[Douglas D. Williams]

Eric,

What Stan and Mitch said. ;-)

Yep, the R75 needs to be in CW reverse.

Like most modern receivers, you can change the R-75's CW side tone over a
wide range (I forget how wide). I keep mine on 700Hz, because that's what I
like.

One "quick and dirty" way to calibrate Argo with your receiver (and the
method I use), is to tune to WWVB on 60 kHz, and adjust Argo's calibration
as you watch the signal scroll across at different Argo speeds. WWVB is so
strong I have to use the R-75's attenuator and turn the audio gain way down
so Argo isn't driven into clipping. Make sure you let the R-75 warm up
before calibrating it. Mine takes almost an hour to achieve best stability,
and this is indoors with the OCXO option installed. This is not a concern
for those who have theirs GPS locked.

73, Doug KB4OER




On Mon, Dec 3, 2012 at 9:16 PM, Eric Smith <esmithmail at gmail.com> wrote:

> Thanks for the help, Stan!  Good info .. just what I needed to know.
>
> Yes, the G0MRF preamp is quite tight.  I've used it at 2200m before
> and it is tuned right where it needs to be ...
>
> It works great, too.  I wish I had another and I'd keep that one tuned
> to 185.3 ....
>
> I'll be listening at 2200m tonight.
>
> 73,
> Eric KD5UWL
>
>
> On Dec 3, 2012, at 1:08 PM, "Stan, W1LE" <stanw1le at verizon.net> wrote:
>
> > On 12/3/2012 12:51 PM, Eric Smith wrote:
> >> Please remind me ... it has been a while but I now finally have my
> >> radios going after moving again:
> >>
> >> If I have my R-75 tuned right on a specific beacon's frequency, then
> >> that signal will appear in Argo at the frequency of my side tone,
> >> correct?
> >
> > Correct. The Beat Frequency Oscillator (BFO)or the sidetone is the
> offset at audio frequencies.
> > The side tone may be different for other radios,, eg ICOM IC-703+ has a
> 800 Hz side tone in CW demodulation.
> > Other radios have a 600 Hz sidetone.
> > The resulting audio may change with USB or LSB demodulation or a CW
> reverse or the regular CW demodulation.
> >>
> >> So if sidetone is 700 Hz, then in this scenario the beacon would
> >> appear at 700 on the waterfall display, right?
> >
> > Right, plus or minus the local oscillator accuracies
> >>
> >> Also, it seems like the last time I got this working I had to use the
> >> Reverse feature (CW-R) but I can't remember why.
> > A perculiarity of the radio. Their design engineer's choice. Some radios
> allow a change with a menu.
> >
> > For accurate calibrations I use a HP 3336B signal generator with an
> external GPS/DO reference at 10 MHz.
> > For ARGO ( a great program ! ) I calibrate the soundcard first,
> injecting a audio tone at 1000.00 Hz
> > or any other known accurate freq you have.
> > Then I connect the radio audio output to the soundcard and inject the RF
> freq I am listening to.
> > For example: if I am listening to an RF of 137.000 KHz and my RX has a
> sidetone of 800 Hz in CW reverse,
> > then I would expect to see the test signal at 800 Hz in ARGO. Then
> calibrate out the minor differences due to your radio's
> > LO accuracy.
> >
> > As I recall the G0MRF preamp has a tight bandwidth. Is it tuned to where
> you want it ?
> >
> > Stan, W1LE    Cape Cod   FN41sr
> >
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