[BC] 110 V DC AC/DC radios 5 tube all american

[DHultsman5@aol.com]

In a message dated 12/2/2006 8:05:39 PM Central Standard Time,  
paul at amtower.com writes:

Was only  dangerous if you put the plug in the wall the wrong way.... Good
thing for  polarized plugs, huh?
Paul Smith



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We need to give the RMA industry credit in many cases the typical AM   5 tube
AC-DC  or ackydac as they were called went out of their way to protect  
consumers for the potential of having the non polarized plug on the AC cord  turned 
over.  Mose of them were in plastic cases and all had plastic  knobs.  I 
recall the Hallicrafters S-38 series low cost receiuver was an  AC/DC as was the 
National SW-54.  The chasis was isolated from the meteal  exterior case by 
rubber grommets.  I believe the Speaker leads and  earphones were also transformer 
isolated.  But if you accidently hooked the  ground up wrong the breaker on 
the service would trip.  Also if it was  hooked up wrong the antenna lead 
common would be come hot.  After a shock  on the antenna once I became aware of 
polarity for AC.  In later life  whenever using  and AC/DC device I always tried 
to use an isolation  transformer on the AC line feed.
 
I worked at a Radio Station where they had a AC/DC TV set and they had put  a 
jack on the speaker so they could tape audio.  In several previous  incidents 
I even placed an isolation transformer the audio line to reduce  to potential 
hazard.
 
Most of these types of  receiver sets are now gone away and most gear  uses a 
power transformer. Some transmitters even use a transformer just for  
isolation.  For example our last AM product line used 220 VAC single phase  and three 
phase. In any case we could have rectified the line coltage directly  and 
filtered the ripple as the voltage used was around 210 VAC.  The use of  
transformers elminated the potential of ground loops and provided taps for  voltage 
ranges from 190 to 250 VAC.  Several companies are now using  switching 
techniques and using AC  direct with no transformers.
 
Dave