No nonsense 50 MHz kW PA

KB7Q sværger til KISS -Keep It Simple Stupid, når han bygger radioudstyr. Skal man bygge et LDMOS PA synes det ofte som at selve PA trinnet er lagt det mindste. FET switche, kontrolkredsløb m.m. fylder en væsentlig del af bygge projektet. Her er et eksempel på et 50 MHz LDMOS PA med simple (dumme) relæer og uden alle kontrolkredsløbene. Det er selvfølgelig en risiko at udelade kontrolkredsløb, men KB7Q beskriver det således: Of course one can certainly add protective measures like over drive, over temperature, and high SWR lockouts, but then we’ve moved beyond KISS! Lest Murphy hear me I’ll just whisper this, ” I have yet to blow up one of these amps”. I use a check list 100% of the time to make sure I’m connected to an antenna, SWR is good, drive level set, and the PTT line activates before operating. Over driving, or excessive heating will be what kills an LDMOS amp. Typically a shorted or open output line will blow up capacitors or vaporize the PCB traces and the device will survive. 

Læs beskrivelsen af 50 MHz PA trinnet her.

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