[ARC5] Receiver input impedance...

[Kenneth G. Gordon]

I have wondered about how much of an improvement in receiver operation 
could be achieved by adding an Un-Un to the antenna input.

I've always felt that "matching" impedances is the correct thing to do in every 
case.

Doing some simple calculations, it appears that with the 12SK7 RF amp, the 
input impedance is about 4K ohms, based on the grid-to-cathode 
impedance.

Thus, it seems to me that an 80:1 Un-Un might improve matters somewhat, 
perhaps by improving the S/N ratio, especially in a noisy environment....like 
mine.

Has anyone here tried this? If so, how did you build an effective 80:1 Un-Un? 
What core did you use? A toroid? Which one? How many turns primary and 
secondary? How did you calculate these? Is there an "on-line" calculator 
which could help? Do you think it would be worth the effort?

Etc?

Enquiring minds need to know.

I am thinking that this might be applicable to my other Boat Anchor 
receivers...

Ken W7EKB