[amsat-bb] Re: Rotators
Gary "Joe" Mayfield
gary_mayfield at hotmail.com
Mon Sep 10 20:29:43 PDT 2007
I did not know the EMOTATOR was available in North America. It sounds
ultra-cool and like another item I need to lust after - truly a BMW of
rotators. Is there any place on the web to learn more?
AMSAT # 21357 - Not near as old as 439!
From: John Beanland [mailto:spectrum.ma.ultranet at rcn.com]
Sent: Monday, September 10, 2007 9:44 AM
To: Gary "Joe" Mayfield
Cc: 'Eric Christensen'; 'AMSAT-BB'
Subject: Re: [amsat-bb] Re: Rotators
At 22:14 9/9/07 -0500, you wrote:
>If by available you mean currently made -- Alpha Spid is probably the Lexus
>of AZ/EL rotors -
>It is the one I lust after -- but my Yaesu has done just fine.
10th September 2007
KK0SD de S.I.,
Be careful with the Alpha Spid. Check the fine print in the specification.
Last time we checked it was designed as, and built as, a 12 volt motor
Unfortunately 12 volts does not give sufficient acceleration to track high
elevation angle passes when the bird is "high in the sky".
Their solution is to increase the power supply voltage; they give
performance figures for 18 volts and also 24 volts supply. The 24 volts
supply is needed to track the very high angle passes. There is no mention of
temperature rise (and reliability?) with 18 or 24 volts supply.
Note: It uses DC motors so the torque and available acceleration increase
with applied voltage. But do you want to apply 50% or 100% over-voltage to
get your required performance?
A much better choice, in the Cadillac class, is the EMOTATOR EV-800-D7X.
This uses 24 volt DC motors. There is also a "gold plated" version, the
EV-800-DX; this is a BRUTE. Both of these models are compatible with control
systems (NOVA, Uni-Trac, SatPC32, and many more) that are "standard" in the
Amateur community. The EMOTATOR control box accepts both 115v and/or 230v AC
These twin axis rotators will happily swing a 6ft solid dish without any
We supply them to our weather satellite system customers and also to
government customers, who use a 7.5ft dish for S-band telemetry reception.
Tracking performance is excellent. When driven by Uni_Trac or similar
(10-bit or greater A/D) unit, the overall (both axes) system tracking
hysteresis is about 1.5 degrees RMS.
The EMOTATOR rotators are available from Spectrum International, Inc,
73s, de John G3BVU/W1 amsat 439 (a very old number).
C.J.Beanland, MSEE, C.Eng., MIEE, MRAeS.
Spectrum International,Inc. spectrum.ma.ultranet at rcn.com
P.O. Box 1084, Tel: (978) 263-2145
Concord, Mass. 01742. Fax: (978) 263-7008
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