Where to buy tunnel diodes?

Just had an idea involving tunnel diodes for Q boosting of LC resonators. But none of the big distributors seem to sell tunnel diodes. Can anyone recommend a convenient place to buy small quantities of tunnel diodes (or Gunn diodes) with good documentation?

Tunnel diodes have been obsolete for years. Your best bet for obtaining any would be eBay. Russia made them for quite a while after the west stopped using them. For documentation, you'll have to look at your favorite datasheet site and hope for the best.

Try:
https://www.rfmw.com
then enter for "Tunnel" in the search box.

If you are working at frequencies no higher than a few MHz, consider using Lambda diodes. They also have negative resistance properties but are less suitable at high frequencies.

Brian.

Then what is the current preferred method of creating a negative resistance with a few components?
Figures. Hopefully I don't end up on some FBI watch list...



Yeah I had come across them as well, but no stock currently. Is Aeroflex owned by MACOM? Maybe I should give them a call.

I'm looking at frequencies between 50-150MHz, but thanks for the tip.

You might (needs experimentation) be able to reach 150MHz using SMD to keep inductances low. There is no theoretical top frequency limit but the requirement for two devices and wiring limits the minimum L and C you can practically achieve. You can make a lambda diode from two JFETS or one JFET and a bipolar transistor. Essentially they are wired across each other so each tries to limit bias to the other. Search for "Lambda diode" for example schematics. You still end up with a two terminal device with similar charateristics to a Tunnel diode although the valley voltage may be a little higher.

Brian.

MACOM Technology Solutions in Lowell MA USA still makes tunnel diodes. For example, MBD1057-08052 is a 0.4 pf Cj Germanium diode.

For Q boosting of LC resonators, Brian has the right idea with the Lambda oscillator.

These work very well over your required 50Mhz to 150 Mhz.
http://www.vk6fh.com/vk6fh/lambda_diode.htm

I have one here I just connect up to any LC tuned circuit, from audio to VHF.
Its then very convenient to measure the resonant frequency with a digital counter.

you can buy from below link when i was searching the same components got from here


http://shelfkey.com


These is an Indian online store