[Hallicrafters] how to power up old radio with variac

[Roy Morgan]

At 02:34 PM 6/6/2007, Roger D Johnson wrote:
>Roy Morgan wrote:
>...The B+ filter caps are almost certainly DE-formed and will likely 
>overload your power transformer...
>There are no electrolytics in the RAO. It uses the older oil filled
>caps. The ones in my RAO were still fine after 60 years!

Roger,

Wonderful!
I have neither had an RAO nor worked on one, so I did not know this.  Lucky!

The SP-400's are the same way, if they have the original power supply, as 
are a number of other military radios like the LM frequency meter and 
RAL/RAK supplies. On the other hand, I was surprised to find that the 
APR-4Y radar signal receiver of the 40's has electrolytic filter caps, and 
they are equipped with a HEATER to warm them up!

Roy



- Roy Morgan, K1LKY since 1959 - Keep 'em Glowing
13033 Downey Mill Road, Lovettsville, VA 20180
Phone 540-822-5911   Cell 301-928-7794
Work: Voice: 301-975-3254,  Fax: 301-975-6097
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