This is great entertainment. I vote for Jim on this one.
It my be that what we don't know doesn't hurt us, but all rotator
boxes I have ever played with including the PST-61 pale in comparison
to the Green Heron controller - although the PST-61 comes in second.
I don't know anything about Pulse Width Modulation and RFI (or HVAC
costs) but don't think the serious M/M contest stations would have as
many Green Heron boxes as they could possibly afford if there was a
problem. I want two more and am quite sure will question myself five
years from now why I didn't buy them in 2011. I believe if you had a
prop pitch refurbished by K7NV and a Green Heron control box you would
perhaps have the very best and trouble free rotator system possible.
Sent from Stan's IPhone
On Mar 3, 2011, at 3:20 AM, K8RI on TT <firstname.lastname@example.org> wrote:
> On 3/3/2011 3:19 AM, Jim Thomson wrote:
>> Date: Thu, 03 Mar 2011 02:22:20 -0500
>> From: K8RI on TT<email@example.com>
>> Subject: Re: [TowerTalk] OR-2800PX Point and Shoot?
>> Point and shoot?
>> Roger (K8RI)
>> ## The GH box's have a large knob on the front panel....marked
>> off over 360 degs.
>> The digital display always shows the CURRENT heading. You
>> simply crank the knob
>> over from say ZL land to say EU [ 30 deg from me].... and sit
>> back and watch the show.
>> After a brief pause, the rotor will ramp up in speed..like a 9 x
>> speed auto transmission, and once up
> I'd hardly call that "point and shoot", although it is the most basic
> rotator function and the only available with the early TV rotators.
> PST-61 has a feature where you just punch a button to get you "close".
> To me that is "point and shoot".
>> to max speed..whizzes over the pole to EU. When it gets 20-30
>> degs b4 EU.. it starts the slow down sequence
>> and ramps down from speed's 9, down to 8-7-6-5-4 etc... till
>> it's barely crawling along..then stops..exactly at
>> 30.0 degrees. It will put it within .1 deg of where u want it
>> every time.
> 0.1 degree of the heading with a beam than may have 30 or 40 degrees
> between the half power points?
> Even with the largest of HF physically rotatable arrays, "off that a
> way" is far more accurate than needed.
> Even with large VHF and UHF arrays (except for large dishes) 2 or 3
> degrees is great.
>> ## once u start cranking the knob, the display will also display
>> the new heading, or where ever the knob is cranked to.
>> That way you can dial up a specific heading...like 34.6 degs if
>> you like. It's all automatic, no fuss, no muss, and with the
>> ramp up/down... you don't trash gears etc. On ramp up, ur not
>> slamming all the torque on at once.
> I agree with the ramp up and down, but hate the thought of any one
> using PWM control any where near my station.
>> With the PWM
>> motor controller, it ensure u get max torque, even when rotating
>> at slow speeds. PWM just applies max normal
>> voltage.. but with gaps between pulses. IE: they alter the duty
>> cycle to control the speed. Since each pulse gets max voltage,
> And has the potential for creating maximum RFI.
> I'm looking at geothermal H&V for the house. The estimate cost per
> here in central MI where it's presently 7F is about $360 per year.
> heat and air conditioning for a whole year. It sounds cheap until I
> figure it currently costs a tad under $700 per year with a more
> conventional H&V system. That means I'd have to be 120 or 130 by the
> time the thing saved enough to pay for itself and that's with some
> pretty good rebates and tax incentives.
>> that scheme minimizes any loss of torque.
> That'd I'd argue. For 100% torque you need 100% current, 100% of the
> time. You can improve it by using a massive armature in the motor.
> only have the 100% torque for the duration of the pulse plus the
> mechanical inertial which at slow speeds is no where near what it
> be at full speed.
>> IE; if u just reduce the operating voltage to slow down a dc
>> motor, sure it will run slower,
>> but the torque will also drop off really fast. The PWM scheme
>> gets around that.
> It's an improvement, but it does not eliminate the torque fall off.
>> ## Not having ramp up/down capability is a real detriment to rotor
>> life. It makes me cringe when u see a heavy array, that has been
>> turning at 1 rpm for 30 secs..then comes to a crashing
>> halt..yikes. Sorta like driving down the highway at 60
>> mph,....then shifting into park.
> Let it coast. <:-)) On second thought rotators with wedge brakes and
> large antennas do not go well together.
> I operate rain or shine, wind or calm. I hit the brake release on a
> Hygain HDR-300 and though the meter had shorted as it just snapped
> against the peg. It went right by the limit switches and tore up 5
> of coax.
> There are a lot of good rotators out there that use the equivalent
> of a
> "step start" and stop and do not need brakes. Nearly all of the dual
> worm gear rotators seem to do quite well. Although I like the PST-61
> I've been using parts, are expensive and were slow delivery. Now they
> have a stateside supplier that may have improved. They are still
> pricey though. OTOH most, but not all of the parts were standard
> automotive. I think the next one with be the Canadian AlphaSpid.
> were going to come out with an even larger version. I don't know if
> they've done that yet of not.
> I believe MFJ was going to be selling them state side, but I haven't
> found them in the catalog yet.
> Roger (K8RI)
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