Old 8660 RF generator output low

[joeqsmith]

I bought this old HP 8660 RF generator about 10 years ago.  It was listed as working on eBay.  After doing an initial checkout, found it had a problem.  Once I took it apart, I noticed someone had made a note on it about the problem.    Rather than replace the bad parts, they had jumped them out.  It has not had any problems since I went over it. 

I went to use it the other day and the output level was really low.   Pulled it apart and checked all the voltages, all good.  Checked at the oscillators in the mainframe, all good.    Pulled the covers off the RF section and pulled out the board I had repaired way back when.   It looked fine.  Installed the RF section and it all works.      I hate intermittent problems.   

[joeqsmith]

Put it all back together, ran it for a few hours, worked great.   Let it cool overnight and fired it back up today and it's been sweeping for several hours with no problems.   I suspect a bad contact and re-seating the attenuator control board in the RF section may have corrected it. 

[joeqsmith]

Ran all day.  Put it back on the shelf,  hooked everything back up.  Turned it on.  Dead.     Reseated the plug-in, dead.   Pulled the plug in back apart plugged it in, dead.   Reseat all the boards, dead.     Looks like it's the connector from the front controlled.  Reseated that, bingo.   

Plastic has not cracked.  Contacts look good.  Solder looks good.  May need to look at something a little newer....

 


 

[tautech]

Ran all day.  Put it back on the shelf,  hooked everything back up.  Turned it on.  Dead.     Reseated the plug-in, dead.   Pulled the plug in back apart plugged it in, dead.   Reseat all the boards, dead.     Looks like it's the connector from the front controlled.  Reseated that, bingo.   

Plastic has not cracked.  Contacts look good.  Solder looks good.  May need to look at something a little newer....

Now you know where to look you could check continuity with a DMM.
Do you have a trusted DMM? 

[joeqsmith]

     

As cheap as the modern scopes are and as advanced as the handheld meters have become, RF signal generators must be too specialized.  I can't find a 1M - 4GHz, low phase noise, -130 to 10dB, with some basic modulation and an Ethernet interface from UNI-T for $50.  Where is that deal??    

Stupid thing.  I can't get it to fail now.  May be time for a complete cleaning of that RF section.