[amsat-bb] Re: GAAS FET Preamp Component Question

Simone terrando at tiscali.it
Mon Feb 27 00:12:53 PST 2012

Hi Gene,

I don't have read the scematic yet (I will do later in the morning), but I
suppose your schematic is a common source LNA.

If it's so, the ferrite on the drain it's a choke, used as a bias tee to
isolate the RF portion of the circuit (the GaAs FET) from the power supply.

For this purpose, you can use any ferrite bead that has an equivament
impedance in the range of the kOhms in the band of interest. As an
alternative, you can use a big inductance, that should do the trick.


Simone - IW1FYV

Il giorno 27 febbraio 2012 03:41, Eugene Crist <ejcristjr at gmail.com> ha

> I'm planning to build the GAAS FET Preamp for 430 MHZ that's in the 2008
> ARRL Handbook on page 14.37. One of the components on the drain of Q1 looks
> like a ferrite bead. I've never used these in construction before and the
> parts list doesn't specify any particular value or rating. Does anyone know
> what value/rating should be used? Any info would be greatly appreciated.
> Thanks, Gene (KB3ONA)
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