$45 for EA53 is reasonable price, the tube is rare. HP initially
rolled out 410B VTVM with 2-01C based AC probe but the contact with the
tube in the probe was unreliable, customers complained, and HP
eventually converted the probe by supplying overhaul kits for EA53
tubes.

Contact me off line, I have EA53's, 2-01C's, conversion kits for EA53,
and the probe assembly for 2-01C so I may be able to help you.

Jiri Placek
Boyertown, PA

Barry wrote:
Does anyone know where these might be available for a "reasonable" price?
The cheapest I've found them for is $45 for a used "pull". I have a nearly
new 2-01C in my ME26D/U but that won't fit in the probe in my HP410B. As I
understand it, some 410B probes came with 2-01C diodes and some came with an
EA53 probe and the two are not always interchangeable.

Thanks,

Barry - N4BUQ