Topband: Norton preamp

[amdx]

Original
>From: "Steve Flood" <flood at ixi.net>
>Subject: Topband: Norton preamp
>To: <topband at contesting.com>
>Message-ID: <001801c73ca6$324b1e90$5fda1341 at STEVES>
>Content-Type: text/plain; charset="iso-8859-1"


>Has anyone tried one of these preamp designs?
>I cannot make sense of the use of the extremely hi-mu FT-50-75 cores in this design. 

http://www.kongsfjord.no/dl/Amplifiers/Ultralinear%202N5109%20And%202N3053%20Amplifiers.pdf


>Steve, KK7UV

   Hi Steve,

 I built a couple of the push-pull amps in 1996 using the pcb design as in the article you cited. I used 
one in Dallas's phasing unit and If I recall correctly, I setup the other for a loop. I didn't have any problem with them. I don't have any way to measure any spec's, so I have to go with Dallas's numbers. I'm inclined to believe what he says, he seems to be very meticulous and conservative.
 As for the hi-mu, these will work at AM broadcast and below, maybe to get the proper inductance
he needed a hi-mu. Note the one turn feedback winding. The small size fit the 2.5" x 2.5" pcb.
 I seem to recall he built a smt board at one time. 

                                                              Mike