Re: Why JFET amp instead of Non-inv Op amp? Do they both not have high Imp?

Hello Fred,

Are you sure that these were JFets and not MOSFets? I've used loads of them,
and specially the BF245 and never had to complain about reliability. MOSFets
requires much more care if not protected, and specially the RF ones 'cause
they have very low capacitances.

The BF245 is a JFET. I have lost quite a few of them but never blew the gate of a BSS84 or BSS123, so far. But maybe that could be chalked up to the fact that I was younger when I designed with BF245. ESD is learned with experience and between my JFET days and my MOSFET days there are about 10 years ;-)

For a WWVB receiver I'd probably start out with bipolars. Depending on where the antenna is they might get the occasional sting when weather runs through and bipolars stomach that better. It's amazing, we had a few small funnel clouds touch down recently and this is California. Here in the mountains that was accompanied by impressive lightning. So I have my antenna on a pole that can be unlatched and tilted down for a preamp swap. That's better than what they see in the flatlands: Missing roofs and trees.

Or maybe you have a damn powerful sneeze...

My wife says yes. Birds fly away in a panic, cats scurry up trees. Which is why I keep a stash of a German Kleenex type brand. No joke, they were advertized as "snort proof".

Regards, Joerg

http://www.analogconsultants.com
.