Peter,
Been there-done that! - You popped one (or maybe two) of the BS170's - easy just to change all 4.
Some folks have even installed sockets for the BS170's - Like "Smarties" always keep a supply close by!
I will dig out some earlier posts for additional cooling (if you wish?) but I think your problem is the Universal PSU - not stabilised enough - over-voltage and/or maybe a voltage spike?
Look at (invest) in a different Power Source I use an "Alinco DM-330MV" for pretty much everything (with Buck-Convertors for different rigs) but you can also PU small LiPO batteries quite cheaply (and use a buick-convertor!)..
Another less expensive (low-noise PSU is made by "Pro-Audio Engineering", designed for the KX3, it will give you a useful PSU - but again, use a buck-convertor!
I'm sure others have favourite PSU's that will give you control over the VDC?
Good Luck!
73
Terry
