Diodes (was 'Re[2]: [HBR] HBR -- Part 8')

[Hopperdhh at aol.com]

Garey and Walt,
 
Thanks for the information.  Makes me glad that I power my old gear  through 
a 10V, 10A filament transformer to buck the (typically 125 volt) line  down to 
115 vac.
 
Garey, I book marked the Drake web site.  Good info.
 
73,Dan K9WEK
 
 
In a message dated 11/2/2008 1:03:42 P.M. Eastern Standard Time,  
waltah at earthlink.net writes:
Garey said:
> There is a phenomenon in  vacuum tubes whereby the heater (filament) and
> cathode of the tube form  a "parasitic diode". One side of the filament 
> is grounded, and so on  negative half-cycles of the filament supply, 
> rectified 60 Hz pulses are  superimposed on the cathode, resulting in hum 
> in the audio.

I  should have waited a few more minutes before trying to answer this!
Thanks,  Garey.

Walt
KJ4KV
 
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