Topband: Norton preamp

[Steve Flood]

>From: Thomas AC7A
> The gentleman associated with the Kongsfjord project, who wrote the 
> article, is very much involved in LW and MW broadcast DXing and may have 
> used the -75 core thinking it is the best core for that application. >


>From: Chuck Hutton WD4ELO
>The 75 (J) core makes a fine wideband transformer from 1 to 15 MHZ and
>actually works decently over the entire MF and HF range.

>From: Dan N3OX
>...it seems that a transformer that has a single turn on one side and has 
>flat gain down to 150kHz
might need a very high-mu core.



Thanks for all the feedback everyone.  I guess what I have trouble 
understanding with the transformers is that if we are talking about a 50-ohm 
system, it has been my understanding that the reactance should be about 4 
times the system impedance, or 200 ohms XL.   With a 1-turn winding through 
a 75 toroid (AL=2750), I calculate 2.75uH which does not equate to 200 ohms 
XL  until 11.5 MHz.   And is therfore much much lower at MF and LF.

Just trying to learn and pull it all together...

Stebe, KK7UV