Rebuild after flooded antenna...

FlightAware ADS-B Flight Tracking
1

Hi guys,

I’ve been out of the scene for a while…

After getting my rig up and running, building my own ant’s etc - got it all nicely arranged, screwed to the joists in the attic, external areal on the ridge line. Feeding well, quite chuffed with it.

With all the bad weather we’ve had over Christmas here in the UK, noticed the rig was reporting sporadic results.
Unscrewed the coax from the filter, only to find water dripping out of the coax!

Needless to say I was a bit hacked off, and only just summoning up the post-hacked-off-interest to rebuild.

Looking at my rig today, looks like I need to replace everything up stream of the USB reciever:

In line amp
Power inserter
Cable
Filter / diplexer

Becuase the biggest cost of all this is that of getting someone with ladders to put the ant up on the roof line, I’d like to replace it with “good as possible within budget” componants.

I’ll post my proposed purchases and links in this thread - if people would like to comment or offer better alternatives, that’d be much apreciated! Also, be useful for other formative users…

I’m UK based, so some of the items that are recommended (PerfectVision amp etc), may not be avilable in the UK (unless someone can post links), so I’ll be looking for alternatives.

I’ll be adding updates on my progress and thoughts here, so feel free to jump in with thoughts and advice ! :slight_smile:

2

COAX

I’m looking at getting LMR400, c20’ (c7meters).

QUESTION:

With LMR400 being pro grade, do they have screw-on connectors, or is it just crimp on , that obviously needs a crimp tool?
Needless to say, I dont have a crimp tool…

3

You can buy pre-made/custom cables.
I bought my lmr400 from here
theantennafarm.com/catalog/

They delivered in less than a week.

Jon

4

Thanks for the tip Jon!

Unfortunately, I’m in UK - I’ll just make my own cables, even if I have to use RG6 for the moment, though :slight_smile:

5

According to Wikipedia, rg6 has 6.3db loss per 100ft @ 1ghz. At 20 feet that would be a little over 1db.
You should be ok.
Try to keep the 75ohm and 50 ohm sections together to reduce loss.
One transition is best.
The USB dongle and rg6 are 75ohm.
The antenna and filter are normally 50 ohm.

6

WF100 is probably a slightly better bet than RG6 (it’s easy to get in the UK, commonly used for satellite installs)

7

Yes, I’d second WF100. Screw on F connectors are fine, but when you put them on use silicone grease. Put it on the screen before you screw the connector on, and then put it inside the connector before you screw it together. It will protect the copper from corrosion, and more importantly help prevent the water ingress that you got before. I use it on connectors on a boat, and it helps a great deal. Water has a habit of wicking up cables through connectors and corroding the contacts and conductors within - it’s worse with salt water, but if you are putting DC power up the coax, you can get electrolytic corrosion as well. With WF100 it should be OK since it is all copper, but RG-6 has a steel core and aluminium screen which being dissimilar metals will react quite nicely in the presence of water and electricity. If you are putting an amp inline, then it would also probably pay to wrap it in self amalgamating tape.

8

I had good results with the filter/preamp from habsupplies/Nevis Computers (http://ava.upuaut.net/store/index.php?route=product/product&path=72_73&product_id=85)
This can be powered via mini-USB or bias-tee. I went for the mini-USB option and the unit is located right in front of the dongle.

9

Moring all,

Thanks for all the replies - cpc.farnell.com/ seems a good source here in the UK (dont know why I didnt think of it before! :wink: )

That WF100 coax sounds good @caius, I’ll see if I can find some of that, and the silicone grease as you mention :slight_smile:

10

Thanks MGunther - looks a good preamp / filter!

With that being an internal component, (i.e I dont have to get “ladder-man” out to replace or upgrade it), I’ll keep that unit in mind for a future upgrade.

11

OK - my parts list so far:

COAX - £13.90 - http://www.amazon.co.uk/Black-Satellite-Coaxial-Cable-Webro/dp/B008VEN2JS/ref=sr_1_2?ie=UTF8&qid=1456662006&sr=8-2&keywords=wf100+coaxial

MH AMP - £11.76 - http://cpc.farnell.com/proception/promhd11h/mast-head-amp-uhf-27db/dp/AP01831

AMP PSU -£11.60 - http://cpc.farnell.com/proception/propsu11f/power-supply-mast-head-f-conn/dp/AP01838?ost=AP01838&selectedCategoryId=&categoryName=All+Categories&categoryNameResp=All%2BCategories

Diplexer / Filter - £3.60 - http://www.amazon.co.uk/Konig-SAT-UHF-VHF-Combiner/dp/B0013D9ZR2/ref=sr_1_1?ie=UTF8&qid=1456662875&sr=8-1&keywords=diplexer

Silicone grease - £2.99 - http://www.amazon.co.uk/All-Trade-Direct-Silicone-Lubricate/dp/B00904MO0Q/ref=sr_1_3?ie=UTF8&qid=1456663130&sr=8-3&keywords=silicone+grease

I’ve got a load of Screw on F-plugs in my box 'o bits - BUT, in the aim of waterproof-ness, how much better would the crimp on plugs + tool be?

What do you guys think to my shopping list so far - any replacements?

12

That amplifier is a UHF amp rated for 470-862MHz, it may not work well @ 1090MHz.

13

Thanks @Obj - helpful as always :slight_smile:

So I know - how did you know the rating of that amp, I couldn’t find that on the page?

14

If you go to the catalogue page it has some more specs (and a really annoying interface)

15

Thanks Obj, do they even do mast head amps in the adsb freq range?

I’ve been looking for hours and darned if I can find one…

16

Inline satellite amplifiers have worked OK for me in the past, stuff like this: amazon.co.uk/gp/product/B001U4KTU6

17

That is exactly the one I am using. I’m getting decent results from it.

18

The best method is compression, not crimp, for RG6, and if you want to really make it watertight, before you put on the connector, slide 3" of heatshrink on, then after the compression, dab on a small blob of ‘electrician dielectric grease’ or silicone grease, slide the heatshrink up over the compression ring and all the way up to the nut, then heat to shrink tightly. Be careful.

Finally, on every outdoor connection, use the silicone grease on the male and female ends then tighten nicely to displace all the air in the connection and seal it up. Compression tools for RG6 and RG6 compression connectors are cheap and can be obtained at any Home Depot or Lowes type store.

The second best method, using screw on or crimp connectors, is to use the silicone grease on the actual connection, then apply "Liquid Electrical Tape’ to the finished connection. It’s cheap. It’s a compound that you brush on with the supplied brush, sort of like PVC glue, and it cures to a clear, elastic covering. It can be easily removed with a pocket knife, but will be about as waterproof as you can possibly get. We use it on outdoor LNB and BUC connections for satellite earth stations and it stays on for years.

If you feel the need, on a long run, to keep everything 75 ohm from antenna/amp to receiver, then use RG-11, or if you want to be exotic, use 75 ohm LMR400 for long runs. awcwire.com/productspec.aspx … coax-cable.

If you are building your own PVC antennas with electronics built in, it is important to seal everything up with PVC glue, as far as the top cap and any reducers, sleeves or other adaptors, then consider making the bottom end a PVC threaded cap connection for easy access to adjust or repair. You can mount the bottom antenna connector right into the threaded cap, using either actual weatherproof bulkhead connectors with O-rings, or using RTV or other compound to keep it sealed.

19

+1 for WF100 by Webro , good cable, lots of clones around though with half or less the screening/braid of the original Webro product.

I have attached the data sheet below.

431×600 242 KB

I use these F connectors from UK ebay seller Rathbone Communications.
They suit WF100 and they also have internal rubber o ring neoprene seal.

ebay.co.uk/itm/Qty-10-High-Q … 3a957eb4a3

20

Thanks for the feedback guys - ordered 30meters of WF100, inline amp, silicone grease, splitter filter from amazon…

@RadiostationX - I have a load of f connectors (with those seals), but I’ll order some of those you mention, just in case! :slight_smile:

@K5ted - thanks for the detailed comment! I’ll order some of the liquid you mention…