วันศุกร์ที่ 25 พฤศจิกายน พ.ศ. 2554

Homemade AZ/EL Ratator controller.

I will design a AZ/EL rotator controoler to use for test communicate in moon bounce 。This design refer.../sv1bsx/actuator/actuator.html in first step.


This is design follow from web to pattern PCB. In actual I use universal PCB to make prototype. Then Pattern PCB evaluate from prototype.


In the box has a transformer. The transformer carrier out 4 Kind of voltage (33、24、12、and 6V)。 I use 33 and 24 to supplied the motor. And 12 DCV for supplied control board. Actuator need 33Vdc to supplied and Washer motor need 12Vdc to supplied.


The meter for indrcated portion of antenna。I used 10mA meter and modify display change the scale to AZ and EL degree meter.
Next step I modify actuator later.

วันจันทร์ที่ 21 พฤศจิกายน พ.ศ. 2554

Calculating Power (dBm and mW) from Peak-to-Peak Voltage

"To calculate the power from peak-peak voltage, the load impedance (Z) must be known. In RF design, the standardized impedance value is 50 ohms, For CATV and video, 75 ohms is common and in audio and telecommunication design, a 600 ohms impedance is often used. Although technically any Z can be used, we will conform to the 50 ohms RF impedance standard on this web page.

The SI unit of power is the watt. In radio, we might see the term dB used. However, dB is a decibel comparison between 2 signals and not an absolute value like the watt. A common and very useful term is dBm. dBm is the measured power ratio in decibels referenced to 1 milliwatt. dBm measures are an absolute power and very useful because both large and small signals are quantified with 1 number. Here are some bullets to contemplate:"


Sourse data www.qrp.pops.net