[Amps] Freescale LDMOS devices / load mismatch survival

[Steve]

Yes, there's no doubting that these modern FETs are generally quite 
robust. For most amplifiers there's a range of phases of high VSWR where 
they will survive ok, and a smaller range where they are most vulnerable 
- usually where the drain impedance goes very high (breakdown volts) or 
very low (dissipation from very high current). The second is probably 
responsible for more failures, but it depends a lot on the diffusions in 
the die.

Steve

> Steve
>
> I, inadvertently, tested mine when the output coax relay gave up it's
> ghost, see the pictures toward the bottom of the page:
>
> http://www.frenning.dk/OZ1PIF_HOMEPAGE/LDMOS_SSPA.html
>
> The LDMOS survived! I was running Digimode at about the 750W level
> when it failed.
>
>
> -- Vy 73 de OZ1PIF/5Q2M, Peter