Re: sBitx v3 - next final MOSFET killed
开云体育Such is the nature of using MOSFETS not designed for RF amplifiers.? I got so sick of the PA failures with my v3, I built one of K9HZ 20w PA boards and just bypassed the entire PA section of the v3.
-------- Original message --------
From: "WZab - SP5DAA via groups.io" <wzab01@...>
Date: 4/12/25 11:39 AM (GMT-05:00)
Subject: [BITX20] sBitx v3 - next final MOSFET killed
Hello,
My sBitx v3 has killed next final MOSFET. Again, as
previously, only one was dead:
However, this time the failure wasn't caused by overheating (the fan was cooling the heatsink and its temperature was ca 30 C) but by SWR.
I was operating my device remotely via WiFi in FT8 mode, and my ATU got crazy. Unfortunately, I could only see the increase of SWR on my laptop, and the connection got broken. I couldn't cease the transmission immediately. When I reached the sBitx, it
already showed the output power 0W.
Well, when replacing them, I have exchanged the mica insulators with AlN ones. Let's see how long is it going to survive now.
BTW. Is it possible to replace IRF510 with other MOSFETs (maybe more expensive, but offering higher maximum voltage and better power at 28 MHz)?
?
73,
Wojtek SP5DAA
-- Mike - K8MCB? |