Leigh W3NLB wrote:

On Sun, 10 Aug 2003 07:34:17 -0400, A E
wrote:

"Eric F. Richards" wrote:

A E wrote:

These *might* be microwave mixer diodes, like the 1N416D, for example. The thing
to look for is noise figure. I have a 1L20 spectrum analyzer plug-in for my Tek
scope, from the same era as your SA (but much much cruder). I have never seen
your SA, but all I can say is that the first mixer in my 1L20 contains a single
diode.
Do yours look like this?

Not even remotely. Here's a pic of the assembly, out of the "can:"

Oh well.

http://www.dim.com/~efricha/mixer-diodes.jpg


Sweet. Looks like a single balanced mixer with the LO injected in the coil on top? I'm
way out of my league here, I'm hoping that someone in the know jumps in here, I'd like
to know myself.
But, I'm guessing you tested those diodes by lifting one lead and determined that they
indeed are dead...

Testing a microwave mixer diode using an ohmmeter will guarantee that
it's dead. They make special low-current meters for testing these
animals.

True, I use a 1.5V cheapie analog meter for testing tunnel diodes, but in my limited
experience, diodes like the 1N416D can be tested with modern DMM with no damage. But you're
right, I should have recommend testing with low current anyways.