13-12-2018, 04:09 PM
(02-12-2018, 08:47 AM)VK6ZFG Wrote: Hi Ron
The MRF492 is rated for a maximum output of 70W. It loses linearity if used above this power level.
I have modified DSE K6349 100W PAs that use two MRF492s from 100W to 130W output. This involved replacing the PA coil with a much heavier gauge wire and likewise the filter coil and capacitors. It also greatly improving the bias circuit which is not just a simple diode based one.
A single MRF492 will not get you a clean 100W especially if a simple diode based bias circuit is used as per the DL5DBM article.
73s
Igor
Hi Igor
The transistor being used in the amplifier is now a 2SC2879. After receiving some excellent advice I discarded the MRF492.
Between natural disasters, I am wiring up the switching relays, so almost ready to go.
73
Ron