On 8/27/18 4:45 PM, Miles via AMSAT-BB wrote:
I installed two 80 foot sections of LMR 600-UF from the shack to top of the tower.
I have the option of installing a tower mounted preamp, but just added a Female to female N-Connector at this spot. Preamp are in the Shack.Higher loss, but I have not Fried a Preamp in 15 years.
I had to replace the two 20 foot sections of LMR-600-UF.They were full of water.
I'm going to take the contrarian viewpoint (again). A LNA in your shack is not going to do you justice if you've already set the noise figure with a long, expensive, attenuator.
160' of LMR600UF = ~$320
80' loss @ 150 = 0.8dB 80' loss @ 450 = 1.3dB
Let's add in 0.5dB of loss for various connectors, and the best you can do is something like a NF of 1.8dB at 2m, and about 2dB up at 70cm. So much for that fancy 0.5dB NF preamp, right?
Why not spend that money on a _good_ or _cheap_ (pick one) LNA, RG-8X/RG-213 at half the price, and add some power to overcome cable loss in the shack? Good grounding goes a long way to protecting your LNA, which should be off during storms.
A preamp (LNA) belongs at the antenna, not in your rig. That is, unless you've attached the rig directly to your antenna. :-)
--- Zach N0ZGO