[Test-Equipment] Old HP RF analyzers - are they worth it?

[John Miles]

> Hi:
>
> I just blew $25 on two HP spectrum analyzers.  Both are the old
> 851B/8551B sytems.

Those are the coolest pieces of gear HP ever made, IMHO. :)  At the time
they came out, they were like something from Area 51.

The power supply is full of germanium power transistors that will probably
need to be replaced due to leakage.  Get some manuals and do a full
supply-voltage check before you run the analyzer for any length of time.
There are protection circuits that will probably shut the analyzer down to
save the BWO until you replace those transistors.  Modern silicon parts are
fine; I forget what I used in mine but they weren't too exotic.

> Here's the question. Is it worth the effort? Can I do basic
> transmitter observations up to 500 mhz?

Sure, they are good to 12 GHz (oops, Gc).  You'll be able to see harmonics,
but you won't be able to measure phase noise unless it's ridiculously bad.
IMD two-tone tests should be possible with wide-enough tone separation (a
few kHz).

-- john KE5FX