Has anyone experienced problems using an IRF530N in a
500kHz PA?. I am using an IRF530N into an L – C – L output network the design
parameters for the network are input:10 ohms, output 50 ohms, centre frequency
502.5 kHz, Q = 12, giving, L1 38µH, C1 3.7nF, L2 84µH, C1 consists of a 3.3nF
fixed capacitor plus a 2 gang 500pF variable, 3mH inductor in the drain. I have
tried driving the MOSFET with a 5v positive peak signal, and with a 3v rms
signal sitting on a +ve bias, I have managed to obtain 5w into a Marconi TF1152A/1
(50Ω) power meter about three times, but when 12v is removed from the PA and
reconnected there is no output, C1 is adjusted for maximum power output, but is
never the same position twice, and there seems to be a very critical adjustment
of the drive to obtain, a) an output, b) anything that looks like a sine wave, although
when I have got it right there is a very good sine wave. Any ideas anyone as to
what may be going wrong?
My direct e-mail is [email protected]
73 Ken Wright M0KHW IO91TV
