[TenTec] OMNI VI+ Frequency Drift

[George , W5YR]

Jan, I use Zakanaka exactly the same way as you described for DigiPan to
evaluate frequency error in the calibration of my Kachina radio.

If you are seeing a different result with the two programs, first try
using them the same way and compare results. That is, use both reading
audio frequency not direct radio frequency.

If there is still a difference, then tune in WWV on AM and measure the
modulation frequency which will be spot on regardless of receiver
calibration. If WWV is on with 600 Hz tone and you measure 598.4 Hz with
either program set to show Audio Frequency, then your soundcard is off by
1.6 Hz. Neither Zaka nor DigiPan allow for "tuning" the soundcard the way
the original PSK31 program did, so just use that figure as an error
correction when measuring the offset carrier frequency at 9,999.000 Mhz.

On my Kachina, the soundcard reads spot on with either program. The
computer stays on 24/7, BTW. The WWV calibration is seldom more than two
Hz in error and frequently is less. That is with the radio on 24/7 and
well warmed up and stabilized. From a cold start, it will be within 5 or
6 Hz and settle to 2 Hz or less in about 30 minutes. 

The least significant tuning step in one Hz, so it is easy to dial in the
correction to the nearest Hz when getting on an exact frequency is
important, which it very seldom is.


The Kachina firmware also implements an automatic calibration to any
specified input r-f frequency. The result of that process, which can
greatly shorten the settling down time, is usually an error of about 3 Hz
or less.

Another quick frequency cal error check is to use CW and tune in the WWV
carrier on say 10 MHz. If everything is aligned properly, the audio tone
should be on say 700 Hz or whatever the CW offset is. On the Kachina it
is software selectable from 300 to 900 Hz in 100-Hz steps. Again, measure
the resulting offset frequency and any error will represent the total
calibration error of both the frequency-determining elements and the CW
offset oscillator.

The Kachina sports a spotting tone when in CW which is software
constructed to be precisely on the offset frequency. Thus, with WWV tuned
in on CW mode, merely pressing the Space Bar generates the spotting tone
which will beat with the WWV-derived signal tone. Zero beat means that
everything is lined up with zero error. When the other methods indicate a
2 or 3 Hz error, this method clearly shows the same as a beat of 2 or 3
Hz - very easy to hear and count, like a piano tuner.

I describe these steps in terms of the Kachina since I do not know to
what extent the same things can be done, or how, with the Omni and other
more conventional rigs. Don't fuss at me for taking bandwidth on the
TenTec reflector to extoll Kachina merits . . .     ;^)

The many features of Zakanaka have finally weaned me from DigiPan! I am
really enjoying using it and highly recommend it for PSK31 operation.
Having been on PSK since February of 1999 I have had a chance to try all
the programs that have come out, and Zaka is king of the hill for now!   

72/73, George      	       
Fairview, TX   30 mi NE Dallas in Collin county
Amateur Radio W5YR, in the 54th year and it just keeps getting better!
R/C since 1964 - AMA 98452   RVing since 1972       Kachina #91900556

Jan Ditzian wrote:
 
> I just did some adjusting of my Omni VI as well, a few months ago, without a
> counter.  I used Zakanakal  Here is how:
> 
>    * Bring up Zakanaka.
>    * Tune in WWV so you can see a bit above or below 10.000 on the display
>    * Adjust so the bright line is in line with the 10.000 mHz. mark.
> 
> You can do the same thing with DigiPan, but you have to do the radio
> frequency +/- audio calculation yourself.  That is, set your rig at 9.999 mHz
> and align with a 1000 Hz. audio tone.  I just now tried both programs.  I am
> lined up in Zakanaka, but DigiPan is a bit off.  I will not say which one is
> right or wrong, but it is only a matter of a few Hz.  You can get pretty
> close.  You do this in receive mode, not transmit.
> 
> With these magic programs, and ham requirements (+/-10 Hz. is pretty good)
> the counter is of little importance.  The real problem is the coarseness of
> the Ten-Tec Omni VI slugs.  For the faint of heart, I did not know what I was
> doing when I began (and I still don't).  All it takes is turning on the
> program and going to WWV.  Clearly, the big fat line is probably the right
> one, and lo and behold, if you look near 10.000 mHz in Zakanaka, there is the
> big fat line.  Or if you tune your USB radio to 9.999 in Digipan, there is
> the line, near 1000 Hz.  If it had not hit me on the head like this, I would
> never have figured it out.  In fact, anyone with a radio can at least check
> frequency alignment this way.  Then all you do is take that screwdriver or
> alignment tool, slip it onto the slug, hold your breath, and bump it.  If the
> line moves, then you are doing the right thing and you now know how big a
> jump to expect.  Whathehell, a factory Ten-Tec realignment can't be more'n a
> hunnert bux, live dangerously.  It's less tension-producing than the first
> time you slipped that arm around a date.
> 
> Zakanaka is still in Beta test, but if you sign up for the Zakanaka reflector
> at egroups.com, you can grab the next version when it comes out (Beta
> versions are only available for 24 hours).  If you are using it for
> alignment, you need only do this once.  However, Art, I see by your page that
> you are now into PSK31, and I think that Zakanaka will cause you to abandon
> your socks.  Remember, though, this is Beta software.  No bitchin', comments
> only.
> 
> 73,
> Jan, KX2A

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