On Mon, 23 Aug 2004 21:25:44 -0400, "O. Alvarez"
wrote:

I'd like to replace 3 2SK19 FETs in a 1970s vintage solid state
AM/Shortwave receiver to see if it improves reception and overall
performance. When looking around the web for possible replacements or
substitutions, I compiled the list below (not sure if they are all
compatible, but they look like they should be).
Should I try to replace strictly with the same part number or should I
try to improve the performance by choosing a "better" FET. I know how a
FET works but I am not familiar with the specs listed below each type.
For example how does Noise Figure and Gain play into the performance
(Sensitivity) of the receiver?
I'll take any advice, suggestions or links to sites that can shed more
light on this topic...

By the way, I didn't want to xpost this message, but if there is a
better newsgroup to discuss this on please let me know. Thanks.

Regards,
Malomarski

---------------------------------------------------
2SK19 Micro Electronics- a fet designed for FM tuner and VHF amplifier
applications
N-CH J-FET
Max Vds 18V
Max Id 10mA
Max Dissipation 200mW
Reverse Transfer Capacitance Crss 0.45-0.65 pF
Gain N/A?
N/A? MHz

---------------------------------------------------
2SK427 Sanyo - for AM tuner RF amplifiers and low-noise amplifiers
featuring ultralow noise figure
N-CH J-FET
Max Vds 15V
Max Id 10mA
Max Dissipation 200mW
Noise Figure 1.5dB
---------------------------------------------------
2SK161 Toshiba -FM tuner applications featuring low noise figure and
extremely low reverse Transfer Capacitance
N-CH J-FET
Max Vds 18V
Max Id 10mA
Max Dissipation 200mW
Reverse Transfer Capacitance Crss 0.1 pF
Gain 18dB
100MHz
Noise Figure 2.5dB
100MHz
-----------------------------------------------------
2SK192A Toshiba- FM Tuner applications VHF band amplifier applications
N-CH J-FET
Max Vds 18V
Max Id 10mA
Max Dissipation 200mW
Reverse Transfer Capacitance Crss 0.65 pF
Gain 24dB
100MHz
Noise Figure 1.8dB
100MHz

The lower the noise figure the better, the higher the gain the
better, the smaller the Crss the better but all must be for the
frequencies of interest of course.

The 2SK427 has a low noise figure at 1KHz whereas the 2SK192, 161,
and others like the 2SK152 and 544 are rated for 100MHz.. The
2SK19 figures are unknown but probably similar or worse than the
427.

You probably won't notice or even be able to measure any
difference in an ordinary AM radio but there is no harm in trying.
In a good SW the 2SK192 or 544 may just barely make a measurable
difference.