----- Original Message ----- From: "John E" johne@tds.net To: amsat-bb@amsat.org Sent: Sunday, August 10, 2008 6:23 PM Subject: [amsat-bb] Yaesu G-5400B calibration

I have a Yaesu G5400B that came in in a box all disassembled.

I put the azimuth unit together and it is working ok, But I am unable to calibrate it. The direction indicator works and follows with the rotor but is off.

Is there a correct way to position the potentiometer when re assembling?

I have followed the manual as to calibration set up.

Any ideas?

Thanks de John KØCQW

Hi John, K0CQW

Calibrate the mutual position of the potentiometer and the gear box of the rotator is very easy.

The azimuth unit of a G-5400B or G-5600B make a rotation of 360°.

Rotate the unit between the limit switches and stop it when the rotator reaches the midle position i.e. 180 ° from one limit switch and 180° from the other limit switch and put a mark outside of it's bell as a reference point.

The potentiometer is a linear 500 ohm potentiometer.

Without to rotate the motor from the above reference point desengage the potentiometer from the gear box. Using an ohmeter rotate the potentiometer by hand until you measure 250 ohm between the center wiper and each end of the potentiometer and try to be the better balanced as possible. Without to rotare the motor from the reference point and without to rotate the potentiometer from the center point reingage the potentiometer into the gear box.

The mechanical calibration between the potentiometer and the rotator gear box is now completed.

Connect the azimuth rotator to terminals A1-A2-A3 of the control box Switch ON the control box. The voltage between A1 and A3 (the ground) must be about 6 volt DC

While rotating the motor fully CCW the voltage between A2 and A3 must became 0 volt and rotating fully CW the voltage must rise to about 6 volt DC

On the rear of the control box and looking from left to right there are four potentiometers in the order they are VR1- VR3 for cal of the azimuth and VR4-VR2 for cal of the elevation.

With the azimuth rotator fully CW adjust VR1 until the pointer of the azimuthal instrument read exacly full scale.

On the bak of control box there is an 8 pin socket for connection to the interface of a PC

From the outside view and rotating clockwise the pin are 6-1-4-2-5-3-7 with

pin 8 in the center.

Connect a DC voltmeter between pin 6 and 8 or to the ground and with the azimuth rotator fully CW adjust VR3 to get exactly 5 volt DC

The calibration for the elevation unit follows the same criteria and procedure.

have fun and

73" de

i8CVS Domenico