[Elecraft] Digital modes on 144MHz only

[Martin]

That's not quite right. The overall system noise is determined by the 
preamp noise figure when mounted as close  to the antenna as possible. 
Cable losses (=noise) after the preamp can be neglected, as long as the 
gain of the preamp is higher than the losses in subsequent components. 
So the cable AFTER the preamp can be pretty lossy. OTOH, too much gain 
from the preamp easily overdrives your transceiver's RX. A good balance 
between gain vs. cable losses is mandatory. The noise figure of the 
pramp is crucial.
If you are satisfied with your transverter's noise figure , mount it 
close to the antenna via a short run low loss cable, if you can. This 
saves the expenses for a preamp.

This applies to the RX path. I'm not talking cable quality or output 
power for TX.


 > Message: 15
 > Date: Thu, 4 Jul 2019 17:11:58 -0500
 > From: Bob McGraw K4TAX <rmcgraw at blomand.net>
 > To: elecraft at mailman.qth.net
 > Subject: Re: [Elecraft] Digital modes on 144MHz only
 >
 > ..... Start with a mast mounted low noise preamp, then low loss
 > feedline such as 7/8" hard-line, and such. Remember, loss in the
 > feedline adds to receiver noise.
 > ..........
 >


-- 

Ohne CW ist es nur CB..

73, Martin DM4iM