[Amps] noisy sb1000

[Ian White, G3SEK]

George wrote:
>HI
>The sb1000 is working now and keys fine but the PS is really noisy (buzzing)
>unkeyed. Does any one else have any experience with this. any recommendations?
>Im going to try and tighten down the XFMR mount bolts tomorrow to be shure...

This problem was discussed here a few months ago, so it's in the list 
archives somewhere.

Apparently the problem is due to flux leakage from the transformer, 
which makes the sheet steel bottom of the case vibrate and act as a 
"loudspeaker". The solution is to space the transformer upward, using a 
sheet of non-magnetic material such as aluminium or even plastic. The 
thicker, the better; but even 1/8in was said to give a big improvement.


-- 
73 from Ian G3SEK         'In Practice' columnist for RadCom (RSGB)

http://www.ifwtech.co.uk/g3sek