View Single Post
Old 4th Dec 2017, 9:45 am   #1
majoconz
Heptode
 
majoconz's Avatar
 
Join Date: Jan 2008
Location: Ashhurst, Manawatu, New Zealand
Posts: 570
Default Systron-Donner 1702 sig gen.

It may turn out to be a lemon, but it's only an NZ$15 lemon! Systron-Donner 1702 sig gen - 100Hz to 1GHz apparently.
Beautifully made in 1981 - mainly 74LS series logic and TO5 tin can analogue IC's - been stored in a damp place with lots of condensation inside the cast aluminium board enclosure - the cadmium plate had started to go off so that was carefully brushed out and vacuumed - the boards were all taken out and left outside in the sun for a couple of days. Mains power fuse popped and a couple of diodes in the power supply but is showing signs of life - the master oscillator is going - only couple of cycles down in 10MHz according to my HP3586A.

I've been working my way slowly through the test procedure - but it only tells you what to look for when it's right, not what to do when it's wrong. Many phase locked loops all tied back to the master oscillator - many tests say 'short this test point to ground and test that the lock light goes out' - trouble is, mine's out all the time! It has great promise and I haven't found anything disastrously wrong, but why doesn't it go....

...and it's frustrating that someone flogged the extension board!
Attached Thumbnails
Click image for larger version

Name:	Top view sml.jpg
Views:	91
Size:	126.4 KB
ID:	153334   Click image for larger version

Name:	Bottom view sml.jpg
Views:	85
Size:	139.6 KB
ID:	153335  
__________________
Cheers - Martin ZL2MC
majoconz is offline