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Monday, 30 July 2012

Have I killed my FT817 - continued

Updated here follow the FT817 tag.

Still looking to see if I can fix the rig (6am this morning before had to go to work) and it seems to just be the choke that shows signs of damage but I will not apply power to the rig yet. The only reason why seems to be the PSU supply BLACK terminal was grounded through the rig RF connection as I had the oscilloscope RF sniffer in line. This meant that the rig ground was connected to the real ground, the rig power lead was (as I found out) floating above ground when normally connected to this supply and one thing lead onto another and phut!

I had run the same setup with a new laptop for CAT control but the USB was directly connected to the laptop, same with an audio interface. That the laptop had not had an external connection to power might explain why I never saw a problem.

My FT897 is still fine as that was connected to a MyDEL PSU at the time and I tested that and a few other PSU, everyone has the chassis connected to ground connected to the black terminal. I expect it was the XM19V PSU (same one involved when a laptop USB rail was killed a few years back when messing with digital interfaces!) For 6W and C5 this might mean I might opt for an SDR option and take an SDR RXTX and a small PA. 

It does appear I can remake the choke as I have the original housing and ferrite and the winding is not going to be impossible to replace. Fiddly but not impossible.

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