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Should I terminate to BNC or N?

Joined
Jan 18, 2010
Messages
162
Location
People's Republik of Massachusetts
#1
I installed a Wilson 301111 (N-Female termination) in the attic, and due to pathway issues I can't run LMR400 (the stink pipe makes a bend, so there's no straight shot to the basement).

So I've settled on going with Belden 9913 (RG-8 Low Loss) which I plan to order from the Antenna Farm and I'm going to request them to install a Male N-Type on the antenna end... but the question is, what should I terminate to on the device end?
The plan right now, is just to hook it to a scanner.
In the future I might try to leverage the cable run with some kind of discone all band antenna - and use a multicoupler to share the run with multiple scanners.

I'm leaning towards going with BNC Male at the other end, but I figured I'd check with all of you.
 
Joined
Jan 18, 2010
Messages
162
Location
People's Republik of Massachusetts
#3
LMR400 is a equivalent to Belden 9913 they are the same size and specs the only difference is 9913 cost more.
Oh good catch - I need to double check the size of the holes I've got going through from the attic down to the basement.. I've got 1 CAT6 already in those penetrations.

I'm sitting a spool of Belden 8281 (RG59), but that's probably the wrong stuff to run.. it's about a 35 foot run.

I'll look at LMR240 now.
 
Joined
Jul 27, 2005
Messages
9,892
Location
Point Nemo.
#4
Or, RG-6. Use one of the online coax calculator tools to compare the losses. You won't hear a fraction of a dB difference.

As for what to terminate with...
If you are going with a larger coaxial cable, like the RG-8, LMR-400, etc. Trying to connect those directly to the radio can be problematic. Heavy cable can put strain on the connectors at the radio and result in damage. Industry standard practice is to usually stop the heavier cable close to the radio, then transition to a lighter cable to make the final connection. I'd recommend sticking with an N connector at the basement end. Then purchase a short whip of RG-58 with a female N connector on one end and a connector to match your radio on the other. Use that to make the final connection. The tiny bit of additional loss won't be noticed, and you'll reduce strain on your radio connector.

This also lets you swap out radios down the road. If the antenna jacks are different, just get a new whip with the correct end on it.
 
Joined
Jun 30, 2006
Messages
7,269
Location
So Cal - Richardson, TX - Tewksbury, MA
#5
The original Belden 9913 was air core with a thin plastic spacer that spiraled the length of the coax. Its not a very rugged coax and its prone to filling with moisture. I've seen 9913 where people tightly taped it to a mast and over time the tape squished the coax flat. Almost everyone I know who has used 9913 had it fill with water and cause problems over time. This happened to me and all connectors were well sealed and it seems over time moist atmosphere will eventually get into the coax due to expansion and contraction with temperature. I would avoid this type of 9913 at all cost.

With larger coax like LMR-400 I would always terminate in an N connector then use a small jumper for BNC.
 
Joined
Nov 27, 2007
Messages
100
Location
Boston/Mansfield, MA
#6
There is absolutely no reason to buy Belden 9913 in 2019 (and there hasn't been for probably 30 years)

If LMR-400 is impractical try LMR-300 or LMR-240, get the standard, not ultraflex, cable to save yourself money and loss.

Regarding termination, which is why you came here in the first place, my suggestion would be a BNC female. Then get a jumper with the appropriate connector for the radio you want to connect. This allows you to use a more flexible (higher loss) cable into the radio to avoid connector strain. Additionally, should that cable fail due to repeated flexure you're replacing a short jumper rather than your entire run. Finally, this will allow you to be flexible with the radio you connect to the antenna without using adapters. LMR-195 would be my suggestion for the lower jumper.
 

CQ

Member
Joined
Jan 2, 2015
Messages
517
Location
Exosphere
#7
Would LMR-400 Ultra Flex work for your? LMR Ultra Flex - Times Microwave

If you plan on using a multicoupler in the future, you could get one with an N input as an option but BNC would be the normal one that you could use today. Or you can get N connector on that cable and use an N/BNC patch cable in the interim. Something like this: BNC Male to N Female Cable LMR-240 Coax

If you're not into replacing connectors on coax then these folks do a great job with customer builds and the price is right.
USA Coax - Custom RF coaxial cables by MPD Digital
 
Joined
Sep 8, 2006
Messages
2,655
Location
Stockholm, Sweden
#8
RG6 are thin and flexible enough to be used for almost any installation. It's extremely costeffective.
Get a $5 coax stripper and twist on the $1 connectors yourself and then use the appropriate adapters for antenna and scanner. It's easy to add a splitter downstairs and a coax powered amplifier at the antenna if it should be needed and no power outlets available, if you get that discone or other multiband antenna.

/Ubbe
 
Joined
Jan 18, 2010
Messages
162
Location
People's Republik of Massachusetts
#10
Thanks everyone - got my LMR240 run yesterday.
I need to clean up my radio/server area before I post pictures of it :)

Here's a shot of my OTA antenna, Wilson 7/8/900 Yagi, and FlightAware ADSB Antenna (need to term the CAT6 so I can hook up the Raspberry Pi in the attic).

antennas2.jpg

Photo Jan 26, 19 06 34.jpg
 
Joined
Jan 18, 2010
Messages
162
Location
People's Republik of Massachusetts
#13
Will the Raspberry Pi be able to handle the temp extremes in your attic?
Supposedly rated from 0°C to 70°C (32°F to 158°F). If it ends up dying, oh well. I'll get another one and figure something out.

After relocating it from my office on the 3rd floor, to the attic - my numbers have jumped: gillham ADS-B Feeder Statistics ✈ FlightAware

Edit: Right now it's 21°F outside, and the Pi's CPU is 66.7°F. It's supposed to be -10 windchill on Thursday, so we'll see how it goes!
 
Last edited:
Joined
Sep 8, 2006
Messages
2,655
Location
Stockholm, Sweden
#14
Standard SDR dongles have poor receivers, bad sensitivity and high internal noise figures. I use the RTL-SDR v1 and when I connect a $40 low-noise amplifier directly to it in my room the range almost doubles with ADS-B. I use 6-7meters of RG6 and that's only 1,5dB loss from the antenna at 1GHz. So I don't bother with moving the amplifier outside to the antenna.

/Ubbe
 
Joined
Jan 18, 2010
Messages
162
Location
People's Republik of Massachusetts
#15
I'm using the FlightAware Pro Stick (Orange), their 1090 Filter, and their 1090 Antenna. I also swapped off the orange housing, and put it in a RTL-SDR aluminum case. If I start to see issues, I'll move it down to the office closet.
 
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