Mike: You should look for an inexpensive cap. checker and add it to your test equipment. Then you will have to decide which caps. to remove from the circuit to test.
I have an HRO 60 that exhibited strange problems in that I could align the IF after about 30 minutes warm up then in about an hour or more the sensitivity would disappear in just a flash. After many hours of chasing voltage and connection possibilities I finally found the changes were occurring in the IF transformers. Inside them were 510 uuf., silver mica caps which were changing in value significantly. I replaced both of them in two transformers and the problem went away. The excruciating part of the problem was that on dry days (I lived in very dry climate at the time) it would not change, but on days when there was moisture in the air it would. I have even experienced problems with ceramic caps that do as you described. So now if I have a problem with a circuit, I not only check the resistors and other components associated with the circuit, I remove all caps and run them through my cap. checker. You won't find a lot of problems with the caps., but they do occur. 73 Jim de W5JO > Thanks Tony > > That makes sense, I'll replace the 510mmf in the circuit since I dont have > the gear to check them. I wonder how you figured out it was cooking before > damage occured? All that stuff is tucked away behind the shield and hard to > see. I have always felt like the silver mica caps were a pretty safe bet > that they are ok, but as I hear stories from different groups it sounds like > they fail like all other 50 year old componets. > > Mike > W0FD
