Heads up. Just lost the twin finals on one of my 955's the other day. No warnings. Transmitting in AM mode at a 7 watt DK. Not over driven. Not over temp. Checked SWR, was fine. Cables fine. Lots of stinky smoke that's for sure. Had to break the factory warranty seal just to make sure it wasn't on fire inside
My second 955 appears to work fine. In fact, got both of 'em back from the factory a few months ago for repairs to the LEDs, talkback levels and SSB shielding mods.
So could the cause of the PA section failure be that I was running it at 14.5 volts all this time? The radio with the blown finals worked okay for a couple of years in the base station with no over-voltage alarms. Or, maybe just the 68 cent MOSFETS giving up the ghost finally?
Both FQP13N10 MOSFETS showed heat damage on the TO-220 casings just above the "Source" pins.
I'll replace all (4) back there and adjust the bias when done. Anyone know what the proper bias setting should be on the 955 and where to check it? Curious... has Stryker revised it lower? Thanks.
Might as well order 10 of 'em :
http://www.mouser.com/ds/2/149/FQP13N10-1009495.pdf
http://www.mouser.com/ProductDetail/Fairchild-Semiconductor/FQP13N10/?qs=mdiO5HdF0KhLCIXwsYy9VA==
My second 955 appears to work fine. In fact, got both of 'em back from the factory a few months ago for repairs to the LEDs, talkback levels and SSB shielding mods.
So could the cause of the PA section failure be that I was running it at 14.5 volts all this time? The radio with the blown finals worked okay for a couple of years in the base station with no over-voltage alarms. Or, maybe just the 68 cent MOSFETS giving up the ghost finally?
Both FQP13N10 MOSFETS showed heat damage on the TO-220 casings just above the "Source" pins.
I'll replace all (4) back there and adjust the bias when done. Anyone know what the proper bias setting should be on the 955 and where to check it? Curious... has Stryker revised it lower? Thanks.
Might as well order 10 of 'em :
http://www.mouser.com/ds/2/149/FQP13N10-1009495.pdf
http://www.mouser.com/ProductDetail/Fairchild-Semiconductor/FQP13N10/?qs=mdiO5HdF0KhLCIXwsYy9VA==