[R-390] IERC Substitute

[Perry Sandeen]

  The problem with modifying any of the original shiny tube shields is that they are made of steel which has a very poor heat transfer rate as compared to copper or aluminum. (Tisha can give us the correct thermodynamic terms).  And as they do not have a *wick* against the glass going to the shield I personally have serious doubts that painting them black will really provide much of an improvement. 

A very practical solution might be to by the aluminum shield/socket 9pin and 7 pin combinations sold by the Chinese on ebay.  IIRC the come in different colors including black. Around a $1 each in quantity of 10 or more.  They are made for the J lock socket but have a hold down spring one might want to remove.

Then go to your local box store and get a roll of aluminum window screen replacement.  You can then cut off enough to make a flexible *wick* to touch both the tube glass and the aluminum shield. You will have enough aluminum mesh left over for the entire BA society. 

For about the same money one can got to McMaster-Carr and get copper mesh screening which is sold by the square foot. 16 X 16 mesh copper screening is around $8 per sq. foot.  A little experimentation will be needed to find the *right* amount to use inside each shield.

If one can’t get the black color from Carswell electroplating in miniature, Lyons N.Y. (Thanks Tisha). 

So for about $50-$60 one can make enough shields for a complete BA receiver.  The last going price for an IREC set for a R 390A receiver was close to $200.

Note: six years ago I was able to purchase all the IERC shields that I will need for the rest of my life for a very low amount from a surplus dealer so this is a theoretical thought but I think the physics principle is sound.

Regards,

Perrier