Its been VERY busy, and so I haven't had much time to post lately ... still not much time at all.
I have an HP 8665B that has an odd problem I thought I'd post in case there are any HP 8665B afficianado's out there.
We recently pulled it from mothballs (a year or so ago). It was new around 1997, and had a problem that someone didn't want to pay to have fixed. As it is such a nice generator (with only about 3 years original "mileage" on it), we got it repaired.
It's acting up now in an odd way. I wanted to get some educated opinions as to whether this sounds like some sort of alignment issue or a true hardware failure.
SYMPTOM: Let's see if I can describe this one... If you set it (for example on CW, 0 dBm, 10 MHz, 1 GHz or what ever), Set for internal reference, and low noise mode to either MODE 3 or AUTO (I don't have any other low noise options).... You view it on a Spec An at a span of around 10 KHz, RBW of any where in the area of 10 Hz up to 300 Hz or so, 10 dB/Div. So it is a nice clean filtered display with a nice smooth Sinusoidal looking peak. Use that as your mental reference image. Now, imagin a very high "skir that looks kind of like FM or noise where all that is left of the clean sinusoidal type pulse is the top 10 to 20 dB, and a noisy skirt starting about -20dBc, with the "noisy" top of the skirt about + and - 30 or more KHz wide (varies greatly), and looks like some kind of phase mode or something. And it comes and goes.
Some times it is clean for a while, and some times it all but obscures the sinusoidal "pulse" (by "pulse" I am referring to the peak of the signal on the spec an).
I'm thinking maybe dirty attenuator from sitting around too long, maybe something going out of lock on it (alignment?) or maybe needs to be re-seated board??
I also had a HARDWARE FAILURE 22 and 23, which I have yet to look up.
I request only to respond if you are somewhat an "afficianado" of the 8665B, or if you have good RF/microwave instincts/intuition.
Have a good one.
I would start by checking mixers and mixer frequency...
Error 22 is VCO out of lock
Error 23 Fraction N loop out of lock
I've seen this, and both times ended up being an alignment...
http://cp.literature.agilent.com/litweb/pdf/08665-90078.pdf
I hope this helps..use the spec an to look at the intermediate frequencies, and if you have one, use a high impedence spec an and T off the signal..for mixing frequencies below 40 MHz, I use a 3585 and the 1 meg input..other wise I use this old GR signal pickoff adapted to the situation
Mike
I used a little "barnyard" technique, and it appears the ribbon cable connector with DB9's between one of the YTO's was intermittent. I pulled it and re-seated it a few times, and the intermittency went away (with the presumption it will come back in a while). It's been cooking for a few days now with a consistently clean signal (as measured on an HP 89441A).
There is a "cal" adjust procedure I'll hold off trying unless I need to, to set the cal "number" for that YTO.
That's a legit technique, I had an old Agilent 3245A crap out a while ago, following the troubleshooting tree it led to a large ribbon cable that eveidently was a problem often enough that it warranted specific mention.
Custom-Cal is offering free repair evaluations on all RF & Lightwave gear and they now have two locations. (www.custom-cal.com (http://www.custom-cal.com))
This fr others who come to this page at a late date. The ribbon cable is viable solution the symptoms described. Five years on bench workng on these on a daly basis the robbon cable has a double connecion and beome flaky. the best solution to this tis to repalce wih part number 08665-61010. It is a continuous that eliminates this problem. then do the microwave loop adjustments. If yo need to know how to do this just reply or email.