[Heath] [Heathkit] SB-401 driver tube shield missing

[Kenneth G. Gordon]

On 23 Dec 2013 at 14:42, Garey Barrell wrote:

> Rob -
> 
> You might want to check the manual for your radio before adding a
> shield.  That is a hot tube and may have it's life shortened
> considerably.  I don't know for sure in the 401, but the Drake TR-4
> specifically does NOT use a shield,even though the shield base part
> is there.  The extended ring of the base is all the shielding
> needed.

Garey and all:

The exact same thing is true for the Yaesu FT-101, although it uses a
12BY7 instead of a 6CL6.

Even so, I ran some tests a year or so ago which proved that by
painting the inside and outside of those solid tube-shields with
flat-black paint, the internal temperature is reduced by 17%...which
is significant.

Ken W7EKB

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