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[TowerTalk] Update on HDR 300 operation question

To: TowerTalk <>
Subject: [TowerTalk] Update on HDR 300 operation question
Date: Mon, 28 Dec 2009 17:33:33 +0000 (UTC)
List-post: <">>


Thanks for the all of the suggestions.  I have since found that there are 
issues with the documentation on my rotor and its actual build details.  I have 
reversed two of the pot connections and now get readings, though way off, 
indicating that the pot's resistance values are off.  I am guessing it relates 
to it being a 3-turn pot and maybe off by a full turn somehow.  I can deal with 
that by rotate it 'down form the too high values with the mast clamp loose.  
The **range** of resistance varies about as expected.  However, the limit 
switch stops are not working well and I now need to recalibrate the whole 
system and may disable them.  Too easy to 'coast by' . 

What really bugs me is that the manual says that '000' is with the actuator arm 
that hits the limit switches must be exactly half way from full CW and CCW .  
This is stated in Section IX for replacement of the pot.  However, I have a 
manual for this same rotor that shows the actuator in the '000' position just 
barely touching the CCW limit switch, Figure 4, detail A.  A total discrepancy 
in the documentation.  This unit is NOT the one that can be centered either 
North or South.  It never states how it is centered or how to go from NE to 
NW.  Since I have never run this rotor, I do not know how it is supposed to 
function and the manual is not good at describing its actual operation.  There 
are two possibilities. 

1. Start with the actuator in the full CCW position, ready to push the CCW 
limit switch.   I assume '000' is  North.  Running it CW should go to 90 deg, 
East and on to 180 deg South and after nearly a full rotation of the antenna, I 
would be at 360 deg, North again.  The actuator should be near the CW limit 
switch.  The display would be seeing an linear change in pot so the numbers 
would simple count up from 000 to 360 if the pot and tronix are calibrated.  
Seems clear enough.  It does mean that if I want to rotate from 30 deg, Europe 
for me to 300 deg, JA , I must rotate about 270 deg CW instead of just 90 deg 
CCW .  I can live with it if this is how it is designed to run and will default 
to this as my assumption of correct operation. 

2. Start with the actuator half way between he stops as the calibration step 
describes.  Set the pot to read '000' as the manual instructs and assume this 
to be North.  Then, I can go from North, CW about 180 deg until I reach a limit 
switch.  That takes me 0 to 180 or South.  Going back to the north, I can 
continue another 180 deg all the way to the opposite stop, again near 180 but 
approaching from the other direction.  However, the display will not transition 
from 000 to 360 and count down to 180.  I assume that in the old days when this 
'fancy' digital display was designed, they had no way to do otherwise.  An 
analog meter would have worked since its display can easily transition from 000 
to 360. 

Anyone want to comment on this basic issue?   Believe me, I am more tired of it 
than you are! 

Tnx , 


----- Original Message ----- 
From: "w3frg" <> 
To: towertalk 
Sent: Saturday, December 26, 2009 1:28:33 PM GMT -08:00 US/Canada Pacific 
Subject: [ TowerTalk ]  HDR-300 wiring question 

It appears that your measurements from the pot in the rotor to the 
controller are correct, but the signals from the pot through the ADC and 
associated circuitry to the LED readout is the real issue. 
Time to get the scope out and look at the ADC inputs and outputs, etc. 

GL 73s  Tom W3FRG 

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