euh, ja de j310 kan voor HF..
de eerste lijntjes van de datasheet:
"N-Channel RF Amplifier
This device is designed for VHF/UHF amplifier, oscillator and mixer
applications. As a common gate amplifier, 16 dB at 100 MHz and
12 dB at 450 MHz can be realized. Sourced from Process 92."
http://www.fairchildsemi.com/ds/J3/J309.pdf
heb die al vaker zien opduiken in SW schematjes, dus zal wel op lagere f werken ...