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Re: [TowerTalk] Update on HDR 300 operation question

To: Doug Renwick <>
Subject: Re: [TowerTalk] Update on HDR 300 operation question
Date: Tue, 29 Dec 2009 05:56:57 +0000 (UTC)
List-post: <">>


Thanks for pointing out the A-B shorting instruction.  It is referred to when 
the PCB is replaced which I did not do.  So, missed it.  Considering the big 
service  loop I now have, I also see no point in the added complexity of limit 
switches.  Especially since this AM I found that I can only achieve a whopping 
90 degrees of total movement.  When I installed this by myself a couple of 
weeks ago, I never dreamed I would need to become this familiar with the 
details.  I don't mind but usually like to use it a wile before I have to fix 
or upgrade it! 

I plan on solving this one way or the other before the ball drops in Times 

----- Original Message ----- 
From: "Doug Renwick" <> 
To: "al n6ta" <>, "TowerTalk" <> 
Sent: Monday, December 28, 2009 8:18:18 PM GMT -08:00 US/Canada Pacific 
Subject: RE: [TowerTalk] Update on HDR 300 operation question 


The manuals can be a little disorganized, but the information is there. 

First you should zero the digital readout system according to the manual 
by shorting out points A and B. 

If you decide to retain the limit switch actuator (I would strongly 
recommend that you remove both the actuator and the paddle arm for 
good), then as the manual says, turn the gearmotor until the actuator is 
exactly half way between the two limit switches.  IMO the limit switches 
have NO useful purpose. 

Then as the manual states, zero the potentiometer. 

The HDR should then rotate from less than zero to greater than 360.  The 
000 setting can be any direction you choose to initially install the 


I'll run the race and I will never be the same again. 

-----Original Message----- 
[] On Behalf Of 
Sent: December 28, 2009 11:34 AM 
To: TowerTalk 
Subject: [TowerTalk] Update on HDR 300 operation question 


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 , 



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