Are there any transistors that behave like sharp or remote cutoff tubes?

[zachomega]

I'm interested specifically in transistor and not IC's.  I like their compactness and typically lower current draw. 

I assume what I'm interested in might be some sort of FET perhaps?  Additionally, it'd be used for small signals and run off of a 9 or possibly an 18 volt supply if that matters. 

-Zach Omega

[Sir H C]

Some of those dual-gate FETs like the ones in the compressor from Walco?

You could try something with two MOSFETs in series and get that sort of effect with the cascode device.

[Ardric]

I've got a couple of dual-gate 3N138's from here: http://www.goldmine-elec-products.com/prodinfo.asp?number=G15333

but haven't yet found a use for them.  Is that the sort of part you're looking for?

[zachomega]

Honestly, I'm not exactly sure what I am looking for.  I have some 3n201's, but they actually seem to be fairly linear...and in the regions where they aren't linear, they draw ridiculous amounts of current or don't provide enough gain.  I put them some of those in a box as a boost and they sound great, however the thing draws more than 10 mA of current without an LED. 

I was just curious though as I was thinking of using two of them in a pushpull scenario for a compressor-ish kind of circuit. 

-Zach Omega

I've got a couple of dual-gate 3N138's from here: http://www.goldmine-elec-products.com/prodinfo.asp?number=G15333

but haven't yet found a use for them.  Is that the sort of part you're looking for?

[Sir H C]

Found this neat quote:

Tubes with variable gain were used in IF amp stages, so automatic volume control (AVC) could be done. Decrease the gain on strong stations so you don't get blasted out when tuning from a weaker station, and also avoid distortion overload from the strong station. Tubes like 6K7, 6D6, 6SK7, and later 12SK7 were variable gain tubes. Usually called "remote cutoff" pentodes, as the tube wouldn't linearly cutoff current flow like a constant gain tube ("sharp cutoff") would. Yes, these remote cutoff tubes would not be usable in an audio amp, but these tubes lived in IF strips, where only a narrow bandwidth of frequencies were to be amplified, and harmonic distortion products fell outside the bandwidth of the output IF filter, and were thus ignored. The audio detector tube would also measure the signal level, and thus could be fed back to the remote cutoff pentode IF tube. And also to any variable gain tubes at the front end of the radio. The audio detector diode was arranged to create more negative voltage for strong signals, and more negative voltage reduces the gain of the remote cutoff tubes.

from:

http://pw2.netcom.com/~wa2ise/radios/aa5h.html