Topband: Preamp shielding

[Thomas Kuehl]

Hello,

I am in the process of constructing a K9AY loop antenna and have some
questions about shielding for the preamp. My plans call for using the W7IUV
preamp circuit and locating it at the antenna. It would be more convenient
to place it in the shack, but doing so will slightly degrade the system
noise figure, due to the feedline loss ahead of the preamp. The feedline is
RG-58C/U, about 125 feet in length.

A 7-pole Chebyshev high pass filter will be placed in the circuit, before
the preamp. My question is in regard to the shielding of the preamp. I have
an aluminum Bud box, and a painted steel box by Hammond. Either can be used
for the enclosure. What is the most effective box material from a shielding
standpoint? Does it matter? Or should I just go ahead and place the preamp
in an enclosure inside the shack?

Regards, Thomas - AC7A (Tucson)