close up picture of the MRFE6VP61K25H 144 MHz prototype.
size is 12 cm x 7.3 cm
at 800W PEP
video of the amplifer running at 50V 2.5A Idq
video of the amplifer running at 44V low Idq (for non linear mode) Board is
black coated for accurate temperature measurement
information are available in DUBUS Q4 / 2010.
Article present one of my latest design with the MRFE6VP61K25H from
Freescale semiconductor, this new unmatched LDMOS transistor allow
design from 1.8 MHz to 600 MHz,
This amplifier can be operated in linear (SSB) operation or class C
(CW/ FSK / JT ) for improved efficiency.
Errata from dubus article,
- PCB supplier is not Taconic
but Arlon, TC350 reference is correct.
- Fig 10 is IMD at 400W , Fig
11 is IMD at 200W (could be read on spectrum screen)
Find detail about the copper heatspreader here,
note that is was done for originaly done for US (4/40) screws,
Also mechanical side is very important in this design, you need to
respect recommendation about mounting surface requirement:
flatness need to be 0.4mils/inch or better
also Freescale recommends the criteria of average
roughness (Ra) of 32 micron-inches