[Elecraft] KX3 - Does It need Preamp for 6M?

[Jim Brown]

On 6/20/2013 10:25 AM, Edward R Cole wrote:
> I would dispute the advantage of mast mounting a preamp on 6m. 

It all depends on how much loss is in your run of coax, and how quiet 
your location is.  The run to my SteppIR is 350 ft of 7/8-in hard line, 
just under 1 dB at 50 MHz, and my QTH is not very quiet, so I'm happy 
with my ARR GasFET preamp at the K3 patch point.

The decision to mast-mount or not is pretty simple.  If you hear the 
band noise increase by at least 7 dB when you connect the antenna, leave 
the preamp in the shack.  If the noise rises by only a few dB, compute 
the loss in your line (see mfr data for the coax you're using).  If the 
noise increases by only 3dB with the connected (and no preamp), you'll 
see an increase in your ability to hear weak signals of roughly one 
third of the line loss. If the noise doesn't increase at all, you'll see 
in improvement equal to ALL of the line loss.

How much is a dB worth?  It all depends how close to the noise level the 
signal is that you're trying to copy.  If it's VERY close to the noise, 
a dB or two can be the difference between making and missing the QSO.

73, Jim K9YC