[Elecraft] sub receiver question

[Wayne Burdick]

Jim Danehy wrote:

> I own K3 # 3355. Love it. Only thing I do not have is the digital  
> recorder and the sub receiver. I am considering the sub receiver. I  
> read in the operating manual that there is a -3 db loss when both  
> receivers are using the "splitter" (common antenna). Is that  
> interpretation correct ? I would probably not be using two antennas  
> except on 160 and 80 which I operate sparingly in the winter. If I  
> use the sub receiver and the main receiver from the same antenna can  
> you notice the -3 db loss ? As we know that is a halving of the  
> signal. One db is the lowest difference your ear can detect.

Hi Jim,

This is correct. Virtually all true dual-receive implementations use a  
3-dB splitter to route the signal to both receivers while preserving  
impedance match.

Most of the time you won't notice the 3 dB loss. It would only come  
into play on a band where both the noise and signals are extremely  
weak, and if it's an issue, you can turn the sub receiver off or use a  
separate antenna.

You'll want a separate antenna anyway so you can use diversity  
receive, which works amazingly well in fading conditions. 160 and 80  
meter operators in particular use this technique.

I'd suggest matching the crystal filters on the main and sub  
receivers, at least those you might be using for diversity receive.

73,
Wayne
N6KR