[AMRadio] Isolation transformers KYV


DOXEMF at aol.com DOXEMF at aol.com
Sat Nov 17 14:22:54 EST 2007


D. Chester writes:

>snip<
>Amongst the best goodies of all were about a half dozen RCA TV isolation 
>transformers, designed for use in a  service shop.  Rated at 400 VA, they 
>have a switch to select your mains voltage, with taps every 5 volts from 105 
>volts to130 volts.  There are 6 outlet recepticals mounted on the top of the 
>case, one set of 3 marked "direct" which are connected to the 105, 115 and 
>130v taps on the primary, marked "low" "medium" and "high".  Three more, 
>marked "isolated" have identical voltage outputs connected to a separate 
>secondary winding.

  Hi Don,
You are so right on with these transformers!
 I had an early WWII receiver, the HF unit and power-supply of a 3 piece set. Forget the ##'s now but it was rated for 110-115 vac. Worked perfectly but just quit one day. I found a open filament tube and the heater voltage was well over 7 V.
  The RCA transformer took care of that. Now with a couple
 of the smaller Halli black case receivers this time, checked the heater voltage first before any extended use and saw the same voltage issue along with the B+ surging over the filter caps peak rating then hanging at and above the operating V.
  Again the RCA transformer came into play for using these radios.

The VIZ/RCA's and other mfg's tapped iso transformers quite often appear at hamfests real reasonably.

73
Bill, KB3DKS/1


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