[Amps] Switching Power Supplies

[Colin Lamb]

"I can't imagine why an amateur would want to use a 
switching supply for a filament. What reason is there to do 
that?"

There could be a few reasons:  
1. The amp has to be transported and weight is an issue.
2. There are no suitable transformers available and a surplus switching supply is handy.
3. Real power transformers cost money and the amp builder is almost penniless and a switching supply is given to him.
4. The builder, in true amateur spirit, likes to complicate something simple.  
5. Just wants to see if it can be done.  

I have the Icom 751A with a built in supply.  It does just as Tom says.  People on frequency do not complain about the hum - but the white noise off frequency is substantial.  This is definitely a rig that neighboring hams do not appreciate.

Colin  K7FM