[AMRadio] Re: RE:Insulating tranformers, chokes, etc.

[Ray Anderson]

>Jay,
>
>Never thought about the rubber shock mounts (made like  miniature motor  
>mounts on a car) catching fire from HV.  I t hink that would happen only if 
>the choke had a dead short f rom winding to core.  As it is, it keeps the 
>frame floating electrically while mechanically supporting and shock mounting 
>the chokes  to reduce the extremely annoying 60 cycle vibration that 
>otherwise is transmitted throughout the metal transmitter cabinet.  As long 
>as the rubber doesn't become leaky and effectively ground the case of the 
>chokes, everything should be OK.  Maybe I should hi-pot from choke frame to 
>cabinet ground from time to time.  If a mount did catch fire, I  think the 
>compartiment in the cabinet would contain the worse of the smoke andx soot, 
>but it would still leave a smelly mess.  I might try to mount rubber and all 
>on some additional  HV insulation.  I like the quietness of the chokes shock 
>mounted.
>
>73,  Don K4KYV

If you just want the acoustic isolation afforded by the
shock mounts and aren't concerned with electrical isolation
and the possibility of flaming rubber (albeit a small possibility),
why not ground the transformer/choke frame with either short
lengths of wide braided copper (like coax shield) or perhaps
short wide strips of copper or brass connected from the component
frame on the top to the chassis on the bottom ? These conductive
straps would be wired in parallel with the shock mounts at each
mount. The flexible conductive straps will not pass any appreciable 
acoustic noise, but will provide an effective DC ground.

73's,	Ray	WB6TPU