Grounded-Gate dual-JFET
VHF Masthead Amplifier




Original design sourced from Elektor BOOK 75; page 56

Claims Gain of 10~20db with a NF of 1~2db

Quote: A secondary advantage of the common gate amplifier is that the difference in matching for minimum noise or maximum gain is much less that the common source cct (and in some cases is even negligible)
RADIO reception requires matching to minimum noise,
TV reception requires matching to minimum power gain to eliminate cable reflection (picture ghosts).

Configuration Gain Input Z Output Z F/B capacity Conclusion
Common Source Higher 1 ~ 20KΩ @100MHz (higher) Similar to I/P 1.0 ~ 10.0 pF Can be unstable !
Common Gate Lower 1/slope (mA/V) 20%
~ 200Ω
(lower)
Similar to I/P 0.01 ~ 0.1 pF Reliable & stable

Vero board layout and prototype.



Remote power supply and tuning box




Single Coax cable for signal/supply/tuning