[amsat-bb] Extended info about calibrating your LVB tracker and G5500 rotor

[Mark L. Hammond]

Hi Burns, good info you’ve shared. I had the same/similar issue on the
azimuth side.  Reducing the voltage top end and calibrating fixed it up.

Mark N8MH

On Wed, Oct 24, 2018 at 5:44 PM Burns Fisher <burns at fisher.cc> wrote:

> For some reason the 5500 and the LVB in my system got out of whack.  It may
> have been when I switched from "450 degree azimuth" mode to "flip" (i.e.
> 180 elevation) mode.  I don't know.  But even after calibrating the LVB
> several times, it would not set the elevation to 180 and setting it to
> 90 degrees ended up something like 15 degrees off.
>
> I took the LVB cover off to access the connections to the 5500, and
> discovered that far from sending an analog voltage of 2 to 4.5V to equal 0
> to 180 degrees as the Yaesu docs say, the 5500 was sending 0V to 5.5 or
> so.  A bit more work found that the LVB did not respond to much more than
> 5V.  I assume that is the reference voltage on the A/D converter.
>
> A look at the schematic on the 5500 found a pot that appeared to adjust the
> voltage to the LVB independently of the meters.  There is zero
> documentation, but the back of the 5500 case actually has 4 pots:  Max
> meter and Max output for both Az and El.  So holding my breath, I turned
> the Max Output pot and sure enough the voltage to the LVB went down.  I set
> the rotor elevation to 180 degrees (by eye) and then turned the pot till
> the LVB readout just started changing.  Then I used the LVB calibration
> procedure to match that location to what the LVB thought was 180.  Voila!
>  90 is now pretty good too.
>
> In retrospect, this is not inobvious; however the fact that the Yaesu docs
> say 2V to 4.5V and the fact that the LVB was not responding beyond a
> certain elevation required some investigation.  Hopefully this little post
> will save someone else from having to repeat the investigation.
>
> 73,
>
> Burns, WB1FJ
> _______________________________________________
> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
> to all interested persons worldwide without requiring membership. Opinions
> expressed
> are solely those of the author, and do not reflect the official views of
> AMSAT-NA.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
> Subscription settings: http://www.amsat.org/mailman/listinfo/amsat-bb
>
-- 
Mark L. Hammond [N8MH]