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G8MNY > TECH 08.08.04 21:27l 58 Lines 2977 Bytes #999 (0) @ WW
BID : 4760_GB7CIP
Read: GUEST OE7FMI
Subj: Radio Shack Rotator info
Path: DB0FHN<DB0RGB<OK0PPL<DB0RES<DB0LJ<LX0HST<HA3PG<IK1ZNW<GB7CRV<GB7CIP
Sent: 040808/1555Z @:GB7CIP.#32.GBR.EU #:4760 [Caterham] $:4760_GB7CIP
From: G8MNY@GB7CIP.#32.GBR.EU
To : TECH@WW
This is an unusual rotator control system. It uses a movable control plate with
3 switches on it. The mains is fed via slip rings the off home contact! And it
uses a pulsed DC motor as a control servo.
DIAGRAM
CAM CAM
SWITCH SWITCH ROTOR
x , x oÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÂÄÄÄÂÄÄ* 3 *ÄÂÄÄÄÄÄÄÄÄ¿ MOTOR
LÄoÄÄoÄÂ><Äo/' oÄ><¿ ÚÄÄÄÂÄoÄÄ> ÚÄ´<ÃÄo x o ³ o ())))Ä¿
Fuse ³ NOT )||( ³ o ³ <ÄÄoÄoÄÄ> === 120u <ÄÄoÄ¿ ===== ³
³ HOME )||( ³ ³ ÃÄ´>³Äo o ³ o ³ ())))Ä´
0u1=== CONTACT )||( 18v³ ÀÄ)ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÁÄÄ* 2 *ÄÁÄÄÄÄÄ)ÄÄÙ 2x ³
³ )||( ³ ³ ³ 6ê ³
NÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÙ³ ³ ³ 27R 5W ³ ³
³ ³ LAMP ÃÄÄ180RÄÄÄÄÂÄÄÄÄÄÄÄÄÄÄ* 4 *ÄÄÄ27RÄÙ ³
³ ³ ³ ÀÄDC DAILÄÄ´ ³
³ ³ ³ MOTOR o ³ CAL R O T A T O R ³
³ ³ ³ o ³ BUTTON ³
EÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÁÄÄÄÁÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÁÄÄÄÄÄÄÄÄÄÄ* 1 *ÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
x = Indicator Plate Switches, >< = Slip Rings, * = External Connection
OPERATION
On moving the control knob & plate these switches power the rotator (lamp comes
on). AC of the right phase direction is passed to the rotator motor & DC of the
right polarity is selected for the dial motor.
The dial plate above the control plate that carries the lamp is moved around by
a DC pulsed dial motor. The on time of this motor just enough to make its' own
cam stay in step with the rotators' cam. The 2 Rs around the dial motor ensure
start up & decay speed are right to maintain about 50% duty power on cycle so
there is plenty of pulse width control to ensure the dial stays in step.
When the dial plate agrees with the control plate the home contact turns off
the power & the lamp goes out.
CALIBRATION
As it is possable to get this type of servo feedback out or step a calibrate
button is provided underneath the controller. If the controller fails to power
off after rotating this usually means the rotator has reached its mechanical
stop & is not providing any more servo pulses. Pressing the Calibrate button
then runs on the dial motor to catch up so the controller powers off OK.
Calibration should not be done often (once/10mins?) as it applies much higher
voltage to the DC motor & heats up the 27R & stalled rotator motor in the
rotator!
MODS
As with other rotators the motor is well over run & a high wattage R (80ê 10W)
in series with neutral will increase rotator motor run time before it overheats
& burns out. And also reduces the lamp power.
Why Don't U send an interesting Bul?
73 de John G8MNY @ GB7CIP
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