Author: Wuhan Zheng
The following comes from real customer feedback, without making any modification. You can visit the following web site to verify. If you are interested in HG MRF477, you may contact us. We can coordinate with the article's author to provide you with the application guidance.
● The article source
● HG produce MRF477
We use HG product MRF477 to make 40W shortwave amplifier
● Transistor Performance
1-30M, third-order intermodulation reach 30dB
● Machine performance
Meet the export standards of the United States
● Reliability
Output reaches 100W using two HG MRF477, current now reaches 15A.The temperature of cooler is about 70 degrees. Many of our Friends are also surprised by the experiment and shocked by the TO-220 packaged product, reaching 100W.
● Debugging process
Draw PCB two times. Our Friends highly think of this PA.
【PCB Real Photo 】
【Gain】
【80 meters of output spectrum】
【40 meters of output spectrum】
【20 meters of output spectrum】
【15meters of output spectrum】
【10meters of output spectrum】
【20 meters of intermodulation testing】
【10 meters of intermodulation testing】
Understanding problems:
1. Third harmonic is high: This form of push-pull amplifier circuit is almost the same as three real multipliers, with the only difference in working point. Transistor multiplier is needed to be set to C class according to the requirement of three frequency multiplier. Refer to ARRL Handbook 2008, Page 14.52
2. On the harmonic and IMD optimization, please refer to http://www.qsl.net/wm5z/qex199907.pdf
3. On transformer and related compensation, please refer to Philips Application note EC6907/EC7213 |
