On Sat, 19 Jan 2013 21:04:50 -0500, Jamie
t wrote:

I wonder if a NPN transistor used kind of backwards around a diode to
take advantage of the negative beta to give you that snap effect would
of done the same for you ?
Jamie

Probably not. Too many other changes would be required.

The problem will be finding a TD with what I guess(tm) has a 5ma
turning point and the correct max capacitance. I would be tempted to
substitute a more modern silicon or GaAs device. The problem is that
they will probably oscillate. Therefore, I would stay with germanium.

My best guess for a substitute are the GE 1N3712 thru 1N3721 series of
germanium TD's. The 1N3712 looks like something close to 5ma
(152-0125-01). The 1N3712 Cmax is 11pf while the Tek part is 18pf.
Close enough.

I haven't gone through all the specs to make sure they're identical
and don't plan to do that until the OP identifies the desired Tek part
number. Too much work.
http://w140.com/tek_xref_tunnel_diodes.pdf

There are various DO-17 packaged germanium diodes in the 1N3712 thru
1N3721 series available on eBay, but no 1N3712.

Clues on TD substitutions:
http://www.reprise.com/host/tektronix/reference/tunnel_diode.asp
Note that this is for a different scope.




--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558