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Greg,? I made an error in reading the schematic and now rewriting my comment.? Most of the comment is correct as written.? The change is in the operation of the 10 Meg range and the voltage at the

I have not read the previous comments other than Greg's original post and will read them during a break to see what you have done.? But first read my analysis of the circuit and let me know if that

FN2960 sounds like and old Fairchild part number, They used a ceramic body with a drop of epoxy, or molded plastic cases. They used their trademark, a styleized 'F' as part of the part number. Michael

George, Thanks so much for chiming in!? As an engineer, my fellows and I had the utmost respect for what HP's designers were able to accomplish and getting info straight from the source is a rare

The NTE part has max value for Vgs(off) of -10V. NSN 5961-00-615-7002 shows part numbers including FN2960 and 1855-0412. It has '3.0 maximum gate to source voltage' which I assume is the same

Hi Tim, Nice. Interesting that it is that accurate at 4GHz after the conversion. I have more than several of these generators and I think they are great. I noticed on mine that if you do a hard reset

That's weird - I thought I saw another response to this thread but when I refreshed the page, it disappeared!? :-(

I put a pair of 2N3904 in for Q13-14 - no change unfortunately.? :-( Yes, it's hard to figure out what Q11 needs to be - HP lists 'FN2960' as an equivalent but that doesn't come back with a match for

I was just looking back at the schematic and OP - I see that you reported Q11 was bad and replaced, but not with the same type. This could be the problem, since JFETs all work more or less the same,

If U2 is railed negative, then Q11 should cut off. Are the parts in sockets? If so, try pulling Q13, which should drop the gain and the current to a very low value. If there's no effect, then try Q14.

The title says it all. You will find many examples in the folder when you download it. Just click on EZGPIB.exe to run. Investigate the?DF6JB Plotter as well. No affiliation, I just like this

I hope so.? ;-) In this setup (Q12 / CR13 out of circuit), the gates of Q15 are offset just a bit - A: -5.0V B: -5.8V? The drains are of course then far apart - A: 2.8V B: 8.46V? and the sources

The problem is obviously revolving around the op-amp which is made up of Q15 and U2. The two gates of Q15 should be balanced at all times, otherwise the output of U2 would be stuck at the +12 or the

Pat, Thanks. I was pretty sure David had the A/B designations swapped, but confirmation greatly appreciated. And it would be very easy for someone reading the thread later to get things backwards with

Might take a few hours to be approved and propagate. [email protected]> wrote:

*[email protected] <[email protected]> *has been created. Have fun! [email protected]> wrote:

With the protection circuitry disabled, the 1K resistor reads 1.87K. U3's inputs are both at -6.4V.? Its output is at -7.4V. Q15 seems to depend on what I'm measuring; for this test, its inputs are

Looking for person (one or more) interested in starting and running a Wiltron/Anritsu equipment group (possibly modeled after this HP-Agilent-Keysight-equipment group) on groups.io. If you are

I bought mine from Globaltest a few years ago, I think I paid about $40 for it. -Dave -- Dave McGuire, AK4HZ New Kensington, PA

Dave, In regard to the collet extractor for APC-7, where did you find one cheap? I've been looking high and low for an inexpensive collet extractor without success. -Eric