Topband: 160m noise

[Jeff Maass]

> -----Original Message-----
> From: topband-bounces at contesting.com
> [mailto:topband-bounces at contesting.com]On Behalf Of Jim Brown
> Sent: Tuesday, November 09, 2004 1:15 AM
> To: TopBand List
> Subject: Re: Topband: 160m noise
> 
> 
> 
> For 160, a very effective choke can be made by winding approximately 10 turns around 
> a 2.5" OD #43 toroid. Fewer turns are needed for higher bands, and the choke that 
> works on 160 will be ineffective on higher bands due to stray capacitance between the 
> windings. So if you work all HF bands you will need multiple chokes in series. As you 
> can see, this can get expensive. :)  But the router is cheap!  


Isn't #43 material the *wrong* material to use for
supressing noise on 160 meters? It's described by 
Fair-Rite as appropriate for 20 - 300 MHz for EMI
suppression. Multiple turns may make it more effective
at lower frequencies, but that's just sloppy.

The appropriate materials described in their technical 
article ( http://www.fair-rite.com/CUP%20Paper.pdf )
are #73 or #31. I believe that an Amidon article also
specifies #77 for 1+ MHz chokes, and I've seen #77
also recommended elsewhere.

73,

Jeff Maass  K8ND