Troubleshooting signal issues UBC125

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Troubleshooting signal issues UBC125

Postby Helix » Mon Jan 02, 2017 11:34 am

Happy New Year all

I've been out of the game for a few months so decided to fire up my ubc125 over the Christmas period, however, I noticed that I wasn't picking up as much as I use to (I listen to airband 90% of the time)... so I just put it down to being quiet because of Christmas period.

So the last couple of days being frustrated I started to have a fiddle - loft antenna ok, rg213 low loss cable all ok (pl259 ends with bnc adapter) so then I tuned in to a frequency and started playing with the end of my cable and bnc connector to scanner. I noticed when I was applying slight downward pressure on the cable in to the scanner the signal was better.

At the moment until I move home I've got the scanner laid on my floor and I've managed to find a 'sweet spot' with the cable slightly angled off a leg on my fan. I know it sounds crazy but see picture =

http://i.imgur.com/eU200UH.jpg

Image

I wanted to know if anyone here can offer some troubleshooting advice because it's a pain trying to fiddle around and I don't want to put pressure around the bnc connector on scanner and risk damaging it.

Since I've found this sweet spot this morning I don't think I've ever heard my radio so busy, getting signals from freqs I've never picked up from before.

Many thanks
Helix
 
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Re: Troubleshooting signal issues UBC125

Postby Kayos » Mon Jan 02, 2017 3:17 pm

I've found adaptors to be very hit and miss (not just for scanning either) so I'm making all my own cables with the correct fitting on each end
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Re: Troubleshooting signal issues UBC125

Postby milly » Mon Jan 02, 2017 4:03 pm

Changing the position of the connector assembly suggests you have a problem amongst that mess of an adapter OR a duff connection on the circuitboard/BNC connection.
Former is most likely so check all of the parts of the coax->PL259->BNC
Damaged connections internally are less likley but still fairly common on radios subjected to abnormal strain on the aerial connector (which you get from connecting heavy adapters and semi-rigid cables to handhelds...sort of like you have done.....)

Generally it is better to use a short light patch lead to join your handheld to your heavy feed.

Also, avoid PL259 if possible...they aren't a good choice for anything above 30MHz
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Re: Troubleshooting signal issues UBC125

Postby G4RMT » Mon Jan 02, 2017 6:06 pm

Those 259/BNC adaptors have been ultra variable quality ever since they were designed (thrown together). The technical tolerances are dreadful, hence why the wobble when connected. The ones RS sell, for example, once attached to the radio are really solid, as the BNC diameter very precisely matches the twist and turn collar, and the angle of the slant slot pulls the connector tight. The centre pin which is again precisely defined in the spec also fits quite loosely into the radio connector. The 259 end is usually better, but the type you have is again bottom end of the market, with plating over god know what - so may also me a bit of a poor fit. Some have a good taper on the screw in for the braid, while others are loose. IS this one of the 'only solder the centre pin types' or does it have the braid soldered too? Always a chance of a single stray strand shorting it out. Personally, I'd chop the entire thing off and put on an N type on the cable which is a good termination, then make up a decent short flexible N to BNC with proper connectors. Much more reliable.
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Re: Troubleshooting signal issues UBC125

Postby Helix » Mon Jan 16, 2017 10:40 am

Thanks for the replies

Just an update, before I went to chop my cable and change connectors I decided to pop in to Maplin and pick up another bnc/pl259 so239 adapter for a few quid... to my surprise the fitting felt much more 'snug' and less wobbly. After trying it out for a couple of days I've concluded this has pretty much fixed my issue as everything I should be picking up is loud and clear and the scanner is indicating good signal strength.

So I'm happy again!

Cheers
Helix
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Re: Troubleshooting signal issues UBC125

Postby m0lsx » Mon Jan 16, 2017 12:27 pm

Helix wrote:Thanks for the replies

Just an update, before I went to chop my cable and change connectors I decided to pop in to Maplin and pick up another bnc/pl259 so239 adapter for a few quid... to my surprise the fitting felt much more 'snug' and less wobbly. After trying it out for a couple of days I've concluded this has pretty much fixed my issue as everything I should be picking up is loud and clear and the scanner is indicating good signal strength.

So I'm happy again!

Cheers
Helix



You are lucky, VERY lucky. As everything antenna in Craplins is Moonraker & that means low quality & with Craplins massive price hike added on top.
Back when I first got licensed I ordered 3 antennas off Moonraker & 2 turned up with faults that even the most basic quality control would have picked up & had the build quality been to an average standard, neither fault would have occurred.
Craplins prove the lie in the "You get what you pay for," quote, as Craplins are very expensive but sell the poorest quality antennas & ancillaries available.
Buy a database from Kimmy JS19 via http://ukscanningdirectory.co.uk/
Or do Google search of this forum via https://www.google.com/cse/home?cx=partner-pub-6291336405621919:2662881632
73 De Alan (M0LSX.)
http://www.qrz.com/db/M0LSX"
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