[amsat-bb] Re: Hygain Sat Antenna's and SSB UEK3000 Sat.
kl7uw at acsalaska.net
Sat May 9 11:34:32 PDT 2009
By your questions I guess you have heard that coax loss between
antenna and input of preamps degrades noise figure (which is why we
put preamps at the antenna in the first place). You do not mention
frequencies for the RG-213 but I am guessing you mean 145 and 435 for
satellite. Ten foot probably will not matter too much on those
frequencies though the higher the frequency the more coax loss gets
(and coax loss adds to the noise figure directly; e.g. 1-dB loss add
1 dB noise figure to the noise figure of the preamp - not good if the
preamp is < 0.5 dB NF). MY best advice then, is to use the lease
length of coax in front of the preamp. Compare how it hears with the
coax and without the coax and decide for yourself.
For 2401 MHz the situation is totally different. 80-feet of RG-6
will kill the low-noise performance of the UEK3000. Install the UEK
at the antenna with no coax or as short as possible a jumper
cable. If you meant to use RG-6 from the output of the UEK that is
quite OK. I use a MKU-232A2 + Drake downconverter on 2401 and run
over 100-foot of RG-6 from the Drake to my FT-847. But the MKU
preamp is directly connected to my 6-turn helix feed for my 85cm dish.
I am considering the purchase of a 10-dBi patch antenna to use on
2401 Leo-sats as it will be easier to point and should not need as
much antenna gain. This will be coupled with a 2400 DEMI preamp and
my second Drake converter.
73, Ed - KL7UW
At 07:44 AM 5/9/2009, Norman W Osborne wrote:
>Hello to All,
>Looking for suggestions for feed lines to my preamps, could I use RG213-U ?
>I am thinking this should be ok as both lines will be only about 10ft in
> >From the preamps, I am using hard line.
>I also have a UEK3000 receive converter for 2.4 , for feedline, could I get
>away with RG6, same cable used for sat TV.
>the run will about 80 ft....
>Getting setup for future HEO.s
>Any suggestion greatly appreciated and many thanks in advance.
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