[Test-Equipment] HP8660 resurrections

[Marco Bruno]

Hi Scott,

At 03.31 10/11/2005, you wrote:
>I have accumulated several various pieces of HP8660 synth sig 
>gens...A-frames, C-frames, -1, -2, and -3 plugins.  So far it 
>doesn't seem that I can get any combination of them to work right.
>Do these units have a poor reputation for reliability?

Terrible.

>Are there any known gotchas or failure modes to start with?
>
>Thanks,

Start replacing all Sprague electrolytics in the mainframe. Many are 
leaky, and the varicap control voltage has to be very stable for the 
PLL to work. Then get a service manual, and start troubleshooting 
from the power supply section... there was a special troubleshooting 
plug-in that goes at the place of the RF section, and helps to 
discover if any basic PLL loop is out of lock. I have one, and is a 
precious thing.

Then, IMHO you can't continue without a complete service manual set. 
The 8660 series was probably the most sophisticated signal generator 
at his time. The manual recommends to re-tune ALL pll pre-tune 
control voltage trimmers (about 100 of them....) every six months to 
keep top-performance :-( - otherwise phase lock may be marginal and 
phase noise could be out of specs.

73 - Marco IK1ODO