[Moon-net] cable losses ?

[Peter Voelpel]

Hi Jurgen,

It will depend on the kind of cable used.
5m difference with 7/8" Cellflex is 0.0735db and 0.133 with 1/2" Cellflex,
but would be 0.45db by using RG213.
I guess the more important difference will be in the amount of
interconnections.
Probably I would go for a 4-port divider in the centre using a total of only
5 connectors and the feedline as large as mechanically as possible.
With that layout, even by using 5 more meters of feedline, my total inter
connection loss will be less then with the 9 connectors in the LWT system.

73
Peter 

-----Original Message-----
From: moon-net-bounces at list-serv.davidv.net
[mailto:moon-net-bounces at list-serv.davidv.net] On Behalf Of Jurgen van de
Glind
Sent: Sonntag, 18. Mai 2008 19:47
To: moon-net at list-serv.davidv.net
Subject: [Moon-net] cable losses ?

 
Hi Lunatic,
 
Just after finishing our new eme arrays ( PA3FPQ/PE1LWT) we ran into a cable
loss question we can't figure out properly.
 
We nearly have the same setup; FPQ: 4x 9elxpol in +config , LWT 4x9el in X
config FPQ is having a 4-port divider in the centre of the frame and uses 4x
5m length as phase line total use of cable =20m LWT is having coax dividers
and is combining the 2 left antennas with a T junction,the 2 right antennas
with a T junction  these 2 t junctions are connected together with n(odd)*
1/4λ lines tog et 50ohm again. Total use of cable  = 15m ( in fact this way
the 4 port divider of coax is having longer
legs)
 
For both systems we have run from each antenna the same length of cable to
the preamp. But the total amount of cable in the system is 5M less in LWT
system. So our simple way of thinking will say LESS cable is LESS losses. Is
this true ?? anyway it's cheaper :-)
 
Jurgen PE1LWT
4x 9elCM xpol Xconfig
Linrad/Map65
 
 
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