[TowerTalk] OR2800 / RT21 cable type

[Paul N1BUG FN55mf]

An update for the archives or those interested. Weather and my health
finally allowed me to climb.

I ran a 390 foot length of RG6 quad shield (because that's what I had)
from the OR2800 junction box to the RT21. I have only had a few hours to
test but so far it seems to have fixed the problem. No false pulses have
been counted when the rotator isn't turning. I set max speed back to 10
and have performed multiple random rotations ranging from a few degrees
to 360 degrees. Calibration is holding. I verified by peaking on my flea
power 10 GHz beacon 5.6 miles away before and after. There was no change
in the indicated direction.

Note: When I say peaked on the beacon what I actually mean is I found
the ~10 dB down points either side and took half way between them to be
the true heading. The dish has a 3 dB beamwidth of 3 degrees so this is
a reasonable indicator. With the old cable I had been needing to
recalibrate after every few turns of the rotator.

Thanks all for the input and suggestions. It appears a single run of
coax works for me. I should have done this when it first started having
issues.

73,
Paul N1BUG



On 8/1/2024 8:40 AM, Paul N1BUG FN55mf wrote:
> I have an Orion OR2800DC and Green Heron RT21 both 3 years old. I have
> had pulse counting errors almost from the start. I know the cable is not
> in good condition as the resistance between conductors is only a few K
> ohms and is not consistent day to day. It used to simply miss counts and
> have to be recalibrated frequently. Slowing max rotation speed to 4
> helped a lot. Yesterday it started randomly seeing pulses when the
> rotator is not moving. This has quickly worsened to the point of being
> unusable. With the pulse counting wire removed from the RT21 it does not
> see any false pulses, so I think the controller is OK.
>
> Assuming it is just worsening cable problems and not a rotator fault, I
> am hoping for a quick temporary fix using what I have on hand for cable.
> Can I use a run of coax for the pulse counting conductors? What effect,
> if any, would that have on the pulse train with a 350 foot run? I could
> use two runs of coax but I guess there would be no advantage since one
> of the pulse conductors is ground.
>
> Thanks for any help or suggestions.
>
> 73,
> Paul N1BUG