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Re: [TowerTalk] Update on HDR 300 operation question

To: <>
Subject: Re: [TowerTalk] Update on HDR 300 operation question
From: "James Wolf" <>
Date: Mon, 28 Dec 2009 18:03:33 -0500
List-post: <">>

What I have done with my HDR-300 is to make East the center.  
If you go West of North, the display reads negative, so that it reads -90 
degrees.  (-90 degs is the readout limit going CCW). When pointing West going 
CW it will read the normal 270 degrees. You can calibrate it such that you get 
270 degs of correct reading, but then you have to re-calibrate your head when 
going West of North.  IOW, -10 is really 350 degrees, etc.
Lightning took out the potentiometer a while back and I installed it where East 
was the middle of the pot range.  

I have also made other modifications.  Brazed the main gear to the shaft, (no 
more wondering if that key is wearing out).  Brazed a Q-lock onto the bottom of 
the platform, which will actually clamp the now modified platform to the main 
shaft and not solely rely on a simple 1/4" key to hold the platform, which it 
would not do without ruining the rotor shaft key slot. I also mounted the rotor 
at the 66 ft. level on a 100' tower where the second set of guys are connected 
with the Rohn torque guy hardware.  This serves two purposes. One is that the 
long mast pipe absorbs a lot of the start and stop torque as well as a constant 
wind swing, which can be a rotor-croaker, and it is much easier to climb to 66' 
than it is to 90 ft.

My potentiometer has failed after about 19 years now, so I will be following in 
your footsteps as soon as it gets warm enough.

Good Luck,

Jim, KR9U


Message: 6
Date: Mon, 28 Dec 2009 17:33:33 +0000 (UTC)
Subject: [TowerTalk] Update on HDR 300 operation question
To: TowerTalk <>


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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