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Re: Elevation Rotors by Prosistel

At 21:25 8/24/02 -0500, you wrote:
>    Hello Group -
>Since most people use the elevation rotor KR-500 or its big
>brother, there is another company that makes an elevation rotor:
>www.prosistel.net    Looks  good......dont have one myself.
>Mike   K8XF
	K8XF de AA1YE   BT

	Yes, an interesting collection of expensive rotators. The azimuth units
look very impressive and are probably very "strong"; in particular it
appears they have two worm gears in cascade providing just about 100%
"braking" torque. However the prospective (satellite service) user should
be aware of the elevation unit's limitations. Its "screw jack" actuator
limits its travel to about 90 degrees (actually -5 to +95); hence the
elevation "rotor" cannot be set to operate in the FLIP mode for tracking
LEO satellite orbits that cross the end stop of the Azimuth rotator. This
means that you may have to wait (typically for a minute or longer), at some
time during a "FLIP mode pass" for the Azimuth rotor to make a 360 degree
turn before you can resume tracking. 

	The "no FLIP mode" limitation makes the unit unsuitable for LEO satellite
operation. However this would not be a limitation for EME operation;
perhaps EME operation is the target market.  

	Twin axis satellite service rotators, like the YAESU 5400/5500 series and
the EMOTO EV-800, provide 180 degrees of Elevation range that can be used
for FLIP mode operation when required. Tracking programmes, like NOVA for
Windows, support FLIP mode operation and output a "FLIP flag" to the
rotator control box when FLIP mode will be required for the next pass.

	The Prisistel Elevation Rotor specifications include a claim of 0.1 degree
accuracy. This implies the use of a 10-bit A/D converter for their 90
degree range. However the published description associates this claim with
using the KCT (and similar) interface units, which have only an 8-bit
capability. Something "does not add up" from the system viewpoint. 

	Another point of interest is the size of the output shaft. A 2inch
diameter pipe can be used for the Prosistel's Elevation shaft. This is
bigger, and potentially stronger, than the YAESU 5400/5500 series which
provide for a maximum elevation shaft of about 1.75 inch diameter. 1º inch
schedule 40 pipe, 1.660" dia, is a good fit.

	However the EMOTO EV-800 series will accept a 2 inch schedule 40 (or
schedule 80) pipe, which is 2.375 inch diameter. Alternatively a 2.25 inch
diameter, 0.25 inch or thicker wall tube, can be used. These are too large
for the "Prosistel" elevation rotor which, as noted above, is limited to 2
inch diameter maximum.

	Look before you leap!  caveo emptor. (if my Latin is still good)   

	73s,   John   "Yankee Echo".
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