[Elecraft] Band Pass Filters for QRP

[Fred Jensen]

Jack,

20-30 feet separation puts your antennas in each others' near fields, 
and they become coupled together [i.e. you're trying to receive on 
conductors that are actually parasitically part of your partner's 
transmit antenna].  Invest in a roll of coax and get them at least a 
couple of wavelengths apart, more is better.  It'll make a big 
difference, and may get the QRM down to levels the K3 can handle.  You 
may still need a couple of filters for 80/40 operation, the the higher 
frequency bands may turn out OK.  Don't even think about 80/75 
operation, we fried the T/R switch diodes in a K3 when someone tried 
that at our M/2 CQP expedition.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2012 Cal QSO Party 6-7 Oct 2012
- www.cqp.org

On 10/27/2011 2:21 PM, Jack Nelson wrote:

> We are generally using K3s and W3EDP antennas or maybe a Buddipole. The
> antennas are 20-30 feet apart, so as you might guess, If one of us is on 40,
> the guy operating on 20 knows it and visa versa.