Topband: DX Conditions

[Jim Brown]

On 12/20/2024 10:53 AM, Mark Lunday wrote:
> Sounds like a great justification for diversity reception, which I can do on my 7610.

It's exactly why diversity reception was invented, probably more than 
100 years ago! The fundamental concept is that there must be two 
receivers, one fed to only one ear, each radio fed by a different 
antenna as widely separated as practical, so that when the two signals 
are most out of phase at one antenna they will be more closely in phase 
at the other.

It's most effective (that is, easier to copy) if the two receivers are 
phase-locked to the same frequency, as is done in Elecraft radios, so 
the frequency of the CW note is the same in both ears. It produces a 
strong characteristic "stereo effect."

They can also be antennas with have different directivity, either 
vertically or horizontally. Whether on topband or at VHF/UHF, the 
different paths can be arriving from different directions, or from a 
lower or higher vertical angle.

Note that two antennas into the SAME receiver is NOT diversity 
reception. Some mfrs of rigs, especially SDRs, are doing this, and 
calling it diversity. It's not.

73, Jim K9YC