Finding Modern RF JFETs or MOSFETs for Receiver Front End, Interpreting Part Numbers

I'm searching for a jfet or mosfet for a receiver front end, but there doesn't seem to be many options. Everything I find seems to be obsolete. The closest thing I've found to a component that matches my needs is the NTE455, VDS is 20V, and if what I read was right it has a bandwidth of 900Mhz. Is there a better way of searching for fet components, or components in general? I usually just use the parametric search on Digikey, but I find this is very limited.

Also, is there a way to calculate the cutoff frequency of a jfet given its parameters? I noticed a lot of datasheets leave this off, whereas almost all RF bjts have the transition frequency clearly listed.

Maybe someone could clear this up as well, is there a way to interpret part numbers or is it completely random? Take the 2N3819 for example, of course the 2N is the series designation, but does the 3819 mean anything? Or were these just chosen serially as the component was first released?

Hello.
The abbreviation is a code chosen exclusively by the manufacturer. It could describe the model, date, revision, release or other information. Some acronyms are really very difficult to understand.
Some acronyms are standard in the history of electronics. For example, the suffix 741 indicates the famous OPAMP, but then each manufacturer can add their own custom suffix.

A great search engine for electronic components is:

https://www.datasheets.com/

of which we have written some tutorials, for example:

https://www.eeweb.com/datasheets-com-a-useful-tool-for-designers/

https://www.eeweb.com/datasheets-com-an-in-depth-look-into-the-options/

The next tutorial will be out soon.
Greetings
Giovanni

JFET bandwidth is usually limited by the shunt capacitance C in the drain circuit. If the drain load is a resistance R, the RC time constant determines the bandwidth.

If the drain circuit is a tuned circuit (the usual case in RF circuits), the tuned circuit determines the gain and bandwidth.