Re: Grounded grid VHF front-end

In article <1r2sqh1.puusef1eope1aN%liz@poppyrecords.invalid.invalid>,
liz@poppyrecords.invalid.invalid says...

 
 

Tubes are noisy. There are MMICS with NFs below 1 dB.

 
There are quiet valves (Nuvistors) and noisy transistors (many),
engineering is a matter of chosing the right ones or using them in a way
which minimises the noise or makes it less significant in the overall
design.
 
 

Once you get above say 100 MHz the tubes that are common do not have the
noise figure of very cheap solid state devices.  A nuvistor at 150 MHz
will do good to prodce a noise figure of 3 dB.  A cheap fet like a U310
will have a noise figure of less than 2 dB and the power supply will be
much cheaper to build. Going to cheap gasfets get you to under 1 dB of
noise figure.  At this time I just do not see why anyone would want to
use tubes in a receiver above 50 MHz if they want a sensitive receiver. 

Years ago I had an Ameco receive converter for 2 meters.  It used
nuvistor tubes.  Worked fine but I put a u310 fet preamp on it and it
was noticable beter.