Scanning! Discone or Eurostick?

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paulears
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Re: Scanning! Discone or Eurostick?

Post by paulears » 06 Apr 2016, 14:57

The black diamond will be fine - BUT - makes sure you seal the connector. Ideally self-amalgamating tape. If you haven't seen it, it's a rubber tape, that you pull off maybe 6", remove the backing paper and then stretch to a foot. This activates the rubber, and it blends with the turn underneath, forming a waterproof shield. As you stretch it as you wind it, it covers the entire thing, aerial to coax. Some people then cover it with electrical tape too. Electrical tape on it's own is NOT waterproof, and many PL259 connectors are pretty nasty things, rusting away quite quickly.

Discones are nice, but ugly things. One thing is certain. You buy any aerial, and a year later consider swapping it. Very often, you swap it based on paper, and get disappointed. This is perfectly normal. I once installed two aerials, one for one purpose and the other for a different one. They worked pretty well. A year later, I discovered I'd swapped the feeder cables, and both radios had been working merrily away on the wrong ones. The difference was nothing at all on the UHF one, but VHF went up a few S points on the meter. Not enough to get into a distant repeater I'd hoped, but just proves gain figures on paper are often written with the benefit of imagination!

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Re: Scanning! Discone or Eurostick?

Post by alunonhisown » 06 Apr 2016, 15:24

Black Diamond has arrived. Scanner should be here on the morrow.
PL259 already factory fitted and sealed with Heat Shrink. Do I need put something over the top of the PL259 as well?
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Re: Scanning! Discone or Eurostick?

Post by paulears » 06 Apr 2016, 16:44

Yes - absolutely. As I said above - PL259 connectors are not waterproof - the water will get into the fairly coarse threads and that isn't good. Seal it properly and you'll never have to worry.

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Re: Scanning! Discone or Eurostick?

Post by kilimax » 06 Apr 2016, 18:24

paulears wrote:I'm going to throw a spanner in the works. I have here a white stick scanner aerial, a dual band colinear, similar to the X-50, a Jaybeam PMR aerial designed for 450-466MHZ, and a J pole for 455MHz. The dual band ham band aerial is excellent in the two ham bands. However, just 20MHz up, it's way down gain wise on the Jaybeam - which is pretty much the same length. The Jaybeam is way down gain wise if I use it on 433MHz. It's hopeless at 156MHz, a handheld works better! Both still receive something. The pathetically small whitestick scanner aerial contains bits of thin wire that are resonant at about 120MHz, 160MHz, 250MHz (or close to),435MHZ and 470MHz. It's by far the best on UHF and VHF air band. The J pole works nicely at it's design frequency - but like the others, drops off quickly. So at the moment, 4 feeders come down, and all have different 'good' parts of the entire frequency range. If you need a small range only - like maybe your interest is marine band, then you buy a marine aerial, but all these aerials I have available are good for something. The whitestick is the best when averaged out, but it has no gain at all on any of it's bands. The jaybeam has the best gain on UHF business band, the dual bander on ham bands, and the little j pole is a dummy load in the sky for marine band.

You seem to have no need for a transmitting aerial - so I would choose something for the bands you like the most. The dual bander have pretty good gain in the ham bands, but are worse than a dipole out of their design band. Mine is just about OK on VHF marine, but the aerial on my van hears more marked outside. I note the ad for the X-50 mentions PMR446 - this seems likely, it's in the band next door, so probably still a bit of gain.

The whitestick aerials are just a load of bits of wire soldered together at the bottom - really crude and basic, but bits of resonant wire do work!
I've never found that to be honest. The Diamond X-50 I have performs exceptionally well outside the Amateur Bands. At my previous QTH, I had a vertical dipole cut for 125Mhz to receive Volmet and the X-50 was 2-3 S points up on the dipole. I also had a Diamond Discone antenna and I found the X-50 to be excellent apart from below 80Mhz and above 600Mhz. It was its equal on most of the bands in between.
Guess installation, height AGL, obstructions etc all play a part. Nobody has the same setup or topography so results vary.
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Re: Scanning! Discone or Eurostick?

Post by kilimax » 06 Apr 2016, 18:34

paulears wrote:N plugs are waterproof by design, and wonderful connectors. PL259 connectors need decent waterproofing. If you have interest in UHF, then better cable is a good move - if the aerial has little gain, losing much of what it does receive going down the feeder is more of a waste? The actual pin and inner ring of an N type will, in an emergency make a push in contact with a BNC socket.
They are excellent connectors. As for being waterproof by design, I would never think of using any connector (including N-Type) without some form of additional waterproof covering. I used to install commercial PMR antenna for a living back in the 80's and you have no idea of the number of repairs I had to do to antenna installations becuse capillary action of water had ruined the entire length of feeder and on many an occasion, I witnessed water coming out of the plug at the back of the radio. BTW, these were the high specification Greenpar or RS component compression types too, not your crap ill fitting Chineese types

Coax should be minimum of RG-213 but like you say, the higher you go, the better it should be. Even RG-213 is way too lossy at 400Mhz. Again, all depends on what it is you want to listen to and how dedicated you are in squeazing out the last db of signal.
Kilimax - Drew
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I've changed radios that many times, I've forgotten what I have :think:

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Re: Scanning! Discone or Eurostick?

Post by paulears » 06 Apr 2016, 22:10

I bought a couple in an emergency from Maplins and they were rubbish in design. The greenpars are the nicest I think - are the RS ones rebadged greenpars?

The rubber seals do a good job on temporary outside setups, but as I mentioned above, extra layers are needed. On the old Home Office towers I used to work on, they had the connector, then self-amalgamating tape, then a layer plc tape, and then the entire thing wrapped in that nasty green gunk covered fabric tape. Disgusting stuff, but they did seem to protect the connection between the RG-213 flexible tails and the RDF550/450 heliax.
Last edited by paulears on 07 Apr 2016, 19:32, edited 1 time in total.

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Re: Scanning! Discone or Eurostick?

Post by kilimax » 06 Apr 2016, 22:31

paulears wrote:I bought a couple in an emergency from Maplins and they were rubbish in design. The greenpars are the nicest I think - are the RS ones rebadged greenpars?

The rubber seals do a good job on temporary outside setups, but as I mentioned above, extra layers are needed. On the old Home Office towers I used to work on, they had the connector, then self-amalgamating tape, then a layer plc tape, and then the entire thing wrapped in that nasty green gunk covered fabric tape. Disgusting stuff, but they did seem to protect the connection between the RG-213 flexible tails and the RDF550/450 helix.
Yeah, the green gunky tape I saw mostly on the Andrews feedline connectors. Disgusting stuff indeed but it worked.
Kilimax - Drew
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Tango Mike Callsign 108TM144

I've changed radios that many times, I've forgotten what I have :think:

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Re: Scanning! Discone or Eurostick?

Post by GeeFull » 07 Apr 2016, 00:25

Ahh Denso tape!
Denso Tape..jpg
Horrible stuff to work with, but brilliant at keeping water ingress out of all manor of exposed to the elements electrical connections/joint boxes! :thumbup:
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Re: Scanning! Discone or Eurostick?

Post by laurel123 » 04 Nov 2017, 11:15

Hello,

I want to know about draft scanning and I also want to know that it is used for large format scanning service?

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