[Amps] Zener? question..

[Ken]

Same dual 4-1000A g-g amplifier, different question. The designer used a 
series string of diodes to provide grid voltage.
Fifteen diodes marked "PTC 2050" I have been unable to find any reference 
to these. I removed one and tested it like
a zener, and never detected a breakdown voltage up to 35v, that's where I 
stopped. Might someone recognize the part
number. I would like to complete the documentation accurately. Thanks.

ken, wa4mnt