I doubt that it's two series zeners, since it's no trick to make a
single zener with that breakdown voltage.

The only application I know of for series connected diodes with that
sort of breakdown voltage is for high dynamic range mixers. But the
pairs I've seen in a single package have a third pin at the junction so
you can also use them for other applications.

I wonder if it might be a low-C varactor. The very low C ones might
possibly consist of two diodes in series -- the manufacturers don't give
any clues since they don't publish any data on the forward bias
characteristics. The breakdown voltage of low C varactors is in that
ballpark, and the packaging is consistent with that possibility.

Roy Lewallen, W7EL

Paul VK3DIP wrote:
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.