John A,
Spot on we have reverse breakdown at around 15 to 20 volts dependant on
current, this is obviously not a high voltage diode!!!
By the way yes the cross bar is the cathode. All the (known) varactors I
have measure a vf around the 0.6-0.7 volt and so do the PIN's I have, though
I don't have a really extensive collection of either, this is why I had
ruled them out but if you know of other examples then its sounding good.

So so far we know:
Forward Voltage ~ 1.4 -1.5 V
Reverse Voltage Breakdown ~ 15-20V
No Visible or IR light emitted.
Small Signal RF like packaging with cross bar indicating cathode.

So what is left?, 2 series 10V Zeners?

I may have to break one open and get out a microscope yet.

Paul.


"John A" wrote in message
...
Hi Paul,

That sort of "mini-L" packaging is often used for vhf components, e.g.
tuning diodes, hot carrier diodes and PIN diodes - and some of these have
forward volt-drops of more than one volt.

You can investigate that suggestion that it is a high-voltage rectifier by
applying, say, 200v reverse voltage via a 1Mohm resistor and measuring the
breakdown (if any) voltage of the diode, or what current flows. Any of the
other suggestions - including mine - will break down.

Are there definitely no markings?


John A
"Paul VK3DIP" wrote in message
...
Hi all I recently purchased a bag of unmarked supposedly diodes and I am
trying to figure out what they are. The clues so far are normal diode
action on a multimeter (ie conducts one way but not the other) but the
forward voltage is high at about 1.4 - 1.5 volts. The packaging is a
small
square black plastic box with flat axial leads one of which has a small
cross
piece on it. This packaging suggests small signal or at least low power.

If anyone wants to look at the mystery diode it is the top one
in this picture.
http://www.users.bigpond.com/pmcmahon/mysterydiode.jpg
The bottom one is a normal glass 1N914 just for scale.

There is nowhere for the light to come out (or in) so they are not LEDs
which is the only other diode like component I have come across with that
high a forward voltage. Could it be two silicon diodes in series?

Any suggestions or even just identifying the case outline would be
appreciated.

Thanks
Paul VK3DIP