In a home-made radio of mid-40's there is a resistor that probably is broken, and it is at the oscillator coil. It is half white and half gray, and at the gray part there are a blue point and the "head" of the resistor is black.Isn't this a too high value to a radio? What can be the function of this resistor?
This radio os a 8 band (broadcast; 120-90-60-49 m; 41-31-25 m; 31 m; 25 m; 19 m; 16-13 m. It has 9 tubes: two 6v6, 6j5, 6sg7, 6sk7, 7q7, 6e5, 5y3 and 6sq7.
Martin.

This sounds like the old "body-end-dot" marking system.
If so, the color of the body represents the first digit
of the value, the color of the end is the second digit,
and the color of the dot is the multiplier. In your
case, the body is either grey or white, the end is
black, and the dot is blue. Assuming standard RMA
color coding, the value is either 80 Megohms or 90
Megohms. You're right, a pretty high resistance, but
not unheard of in the grid circuit of a high frequency
oscillator.

The other possibilities seem to be
1) not body-end-dot marking system
2) not standard RMA colors (unlikely)
3) blue dot was some other color, but faded with age.
Have you examined it with a magnifying glass?
Sometimes you can see traces of an earlier color.

Bill