[Elecraft] K3 on 50 MHz - noise and possible harmonics

[Jim Brown]

On Mon,6/29/2015 9:26 PM, Steve Lund wrote:
> I have received the ferrites recommended by K9YC. The plan is to install
> them on Wednesday. I have both the #43 and #61 material

Hi Steve,

A clarification. #31 is the first weapon of choice for the HF bands -- 
it is effective from the AM broadcast band up to 50 MHz. #43 is slightly 
better above 10 MHz, but much less effective on 80 and 160M. #61 is NOT 
useful  to kill noise below 2M -- it's loss is far too low, low enough 
that it can be used for transformers that handle power at HF.

2-3 turns through a #31 or #43 core puts the choke in the range of 50 
MHz. Because you're using only 2-3 turns, more than one choke may be 
needed. The chokes go on both ends of all the cables connected to the 
router and the modem.

That gear often creates birdies on 30M, 20M, and the low end of 10M. 
Follow my guidelines for RG58/8X coax for these chokes. These birdies 
are created by clocks local to the router, and their frequencies are not 
precise (although they are crystal-controlled). If you have neighbors, 
you'll likely hear their routers too, a few hundred Hz from yours. To 
identify yours, kill power to it.

73, Jim K9YC