[ARC5] Vibrator Power Supplies

[Robert Nickels]

On 12/7/2012 1:51 PM, GDM wrote:
> converted 6 volt DC car radios to AC, by feeding 6 volts AC from a 
> filament xformer into the 6 volt primary winding
I've done that too for old commercial FM radios back when in the early 
days of VHF-FM.   Maybe they ran hot - but since I can't remember one 
burning up it must not have been a problem ;-)   Like a lot of stuff you 
do when the stuff is easy to get and cheap.    I'd like to understand 
what characteristics of the transformer result in this not working as 
expected as I wasn't aware that it was a problem.

One commercial ham rig I am aware of, the Gonset G-77, was a two-part 
unit with the very small (by 1950s standards) RF unit under the dash and 
the modulator and vibrator power supply in a separate box (in the trunk, 
normally).   They sold two power supplies that were identical except for 
one thing:  one just had the DC input for operation from vehicle 
batteries, and the other had an additional primary winding so it could 
run from DC or AC by simply plugging in a cheater-type cord.  I had one 
of the former before trading around to get one of the latter, and it 
works great.    But maybe there are some changes to the transformer that 
I'm not aware of.    Sure makes it nice to have that option.

73, Bob W9RAN