On 05.07.2017 22:11, Robin Humble via luv-main wrote:
Hi Lindsay,
On Wed, Jul 05, 2017 at 07:15:58AM +1000, Ray via luv-main wrote:
... Another way is to run the cable along the outside wall, this being the easier,
that reminds me of throwing an ethernet cable out the window in Toronto years ago to share my DSL with the dialup neighbours in the flat below. then someone pointed out it was "lightning season" and was I sure I really wanted to do that? :-)
fast forward to last week, and I saw what looked to be an earth wire in my ceiling and ran the cat6 cables well below that. dunno if it'll help but thought I may as well.
Note 1: For low rfi reception one needs a GOOD aerial and a radio quite earth ie NOT via the mains earth, its preferable that the radios aerial input circuit is NOT connected to the chassis. A tuned loop is also an excellent low rfi aerial, theses being somewhat easier to match to the HRO and the Racal, both of which expect to see a low impedance resistive aerial.
from your radio antennas I guess you'd know all about lightning risks though...
so I'm about to mount a small 'spider' antenna outside for better ADS-B reception. unfortunately I failed to make a 5 or 7-segment coaxial colinear that worked well. I might mount a much larger AIS antenna outside one day too.
A better option of a homebuilt is a broadside array, ie a number (usually 4) dipoles in parrallel, with a backplane behind it, its impedance is reasonable value (70 or so ohms) and its not as critical to use or construct. Details of these can be found on the net no problems.
DVB-T rtl-sdr dongles are so cheap it's hard to resist playing with this stuff :)
so do you do anything special for your (presumably large HF) masts/antennas from a lightning point of view?
NO, one simply disconnects all electronics from the aerial, it NOT being possible for anything like that to service a direct strike. Note: I have MUCH experience on dealing with lightening and its effect on electronics.
I'm planning a simple RG6 connection of about 5m before it goes into the dongle. the short mast and dome are made out of fibreglass - I figured the less conductive material high in the air the better.
cheers, robin
ObLinux: the USB rtl-sdr dongles attach to one of 4 small Allwinner Cubie or OrangePi Fedora 25/26 arm/arm64 boxes that I have scattered throughout the house. all on 4.10 or newer mainline kernels. _______________________________________________ luv-main mailing list luv-main@luv.asn.au https://lists.luv.asn.au/cgi-bin/mailman/listinfo/luv-main
Lindsay