I would replace the .1 uf & 150 pF at same time and try again. Randy
--- In Repeater-Builder@yahoogroups.com, [EMAIL PROTECTED] wrote: > > I've had a 6.8 µF 35 V capacitor burn up on the GE VHF HB MVP. This is a > filter cap. for the final PA DC voltage, in parallel with 0.1 µF & 150 pF > caps. I replaced it just before Dayton & noticed that the replacement got > rather warm (too hot to touch), so I did a 2 hour burn-in. It survived > just fine, so I concluded that the cap. was simply conducting heat up from > the PA board. The radio worked fine at Dayton, & I've been doing some more > testing at home in preparation for an installation in about 3 weeks. > > This evening after TXing for only ~5 minutes, smoke began to pour out the > back of the radio. After carrying it to the garage to open it, I found C16 > charred once again. My first suspicion was (very) low frequency > oscillation of the RFPA, but if this were the case I think I'd be > experiencing desense, RF feedback & other oddities during testing. I'll > check it on the spectrum analyzer tomorrow (after it's somewhat > "deodorized"), but I doubt it's spurious. > > Any other ideas as to what would cause this cap. to repeatedly fail? > > Bob NO6B >
