længde fra Antenne til radio

Hejsa jeg ville prøve 6 meter men ved ik om jeg har for langt til antennen fra min station har målt afstannen ink toppen af røret hvor antenne skal være 44 meter er det for lang . kabel .. bare det er godt . bruger det der nye 400 husker i helt hvad det heder men det er godt
manger også en god antenne men hvilken en er god . har kigget lidt på en GP15 . retnings antenne er udlukket lige nu ( Konen ) .smiler ...

mvh OZ2BMN

Svar til #1:
Du ka fin bru cox T D. D ska Bar vær go kval. Ski svær a læs SMS sprg.

73
Jen

Svar til #1:
Hej
Hvis det er CDF400 så er det godt kabel... dog ikke godt til drejelige antenner...

http://www.iccom.dk/radio-hobby/CFD400-billed-d ata.htm


vy 73 de oz1ian,

Svar til #1:
Ny kone? ;-)

Svar til #4:
du må få min :-)

Svar til #1:

44Meter er da et stykke
hvad har du ellers i Masten..

og der sker ikke så meget på 6 Meter
det rækker ikke så langt
så skal du snakke med gutterne så er det ikke meget over 20Km det rækker.. med minder man har en kæmpe høj mast... eller man bor meget højt..

den der GP15 og V-2000 de går under
navnet Luft Kølede Dummy load.. de er døve som dørstolper..

Den her er også 6.7M men uden 10M(11M)
http://www.rfparts.com/diamond/cp62.html

Den her har noget Gain
2 x 5/8 på 6M og 1 gange 5/8på 10M (11M)
http://www.rfparts.com/diamond/cp610.html

så er der lidt skub i antennen
OZ2HKK og Jeg bruger den 5/8 del som EDR solgte
det er en ECOMET (ku ikke se om de havde flere ..)
og vi kan snakke 20Km

skal du bruge det til VHF 2M og UHF 70cm er CFD400 ikke så
godt
Men er det til 6M og 10M er det fint nok..

Håber det ku hjælpe..

og tag dig ikke af Akademikerne...
vi kan ikke alle have korrekt Komma og Punktum sætning..

Og ja den Med Konen Kender jeg godt..
hun røg ud så jeg ku få en fin ny Kæreste
hun hed FRITZEL FB53 (5 element til 10-15-20M)

OZ1KS Kenneth

Svar til #1:
den skal være så lang at det samlede system feeder + antenne kan nå ind til radioen

Svar til #1:
Sådan noget som en Diamond CP62 har et gain på 5,5dB. Trækker du så en gang Ecoflex 15 giver det godt en dB's tab ind til radioskuret.
Så bliver det nok ikke meget bedre på en vertikal.

GP15 antennen er heller ikke dårlig. Og så er det jo en trebåndsantenne. Det jeg har hørt er dog at den ikke er helt optimal på 6m...

Hilsen
Jens

Svar til #8: dette hjælper meget på en v2000 antenne


EA4EOZ
an amateur radio electronic enthusiast




Modifications to the Diamond V2000
and similar antennas

This kind of antenna has grown in popularity over the last years because it gives you a decent performance and triband capabilities. But its 50 MHz design is far from optimal. Here you can learn how to improve its 50 MHz performance in a very easy way.

The physics behind the V2000 is very simple. A 5/8 antenna on 144 MHz is almost a slightly loaded quarter wave on 50 MHz. So it is not very difficult to modify the matching network to use the lower 5/8 144 MHz element as a 1/4 wave element for 50 MHz. It's very easy to do. But a quarter wave vertical antenna antenna needs an earth plane to work properly. The V2000 antenna uses a quarter wave radial as a counterpoise for 50 MHz. This is the way its uses to get it working at the three band simultaneously.

There are many antennas working with this principle on the market. Some of them are: Moonraker SQBM-1000, Watson W2000, Comet CX-725 or GP-15 and Diamond V2000. This modification have been performed on a generic V2000, but surely it can be done on all the others as well.


The V2000 and similar antennas have a tuned radial for 50 MHz. Because only the first 144MHz 5/8 element works at 50 MHz, the antenna is not more than a rotated V dipole in this band, a rotated dipole in a way one of its arms is vertical.

The antenna was mounted about five years ago, and it has work always nicely on 2m and 70cm. On 6m I had TV (yes, I still have TV in VHF channel 2 here) noise, sometimes as high as 9+. But it has not been a problem to hear nice signals on the band, of course Es, and some nice TEP and F2. The antenna worked nicely... except if you test it with an antenna analyzer. The antenna had a very erratic SWR curve at 50 MHz, with many nulls between 48 and 56 MHz. The rig's SWR meter shown the same erratic curve. There was no dude the antenna had a problem.

My first try was to adjust the radial length, but the radial was fixed, no tunning possible at all. I tried to tune the antenna cutting physically the radial, but nothing except another erratic SWR curve was obtained. I restored the radial. Here I can't transmit on 50 MHz, so SWR was not a problem at all.

Some time later, playing with MMANA software, I modeled the antenna and I realized what was happening at the antenna. A quarter wave antenna really NEEDS a ground plane to work. Manufacturer do not provided a ground/earth plane for the antenna, only a tuned radial, or counterpoise as it is called some times. The problem is that a vertical quarter wave antenna with only a radial/counterpoise, isn't a vertical antenna. It's a DIPOLE. But it is a problematic dipole:

The dipole does not have balun, so the coax cable and the mounting mast are the 3rd and 4th dipole arm! This will explain perfectly why the antenna has that erratic SWR curve. Googling a bit, I found a message from JA7UDA stating the antenna is really directive, with the main lobe just at the 50MHz radial direction. This was the confirmation for me that the antenna was really a no-balun V dipole on 50 MHz.


V2000 simulation on MMANA. As you can see, the antenna's lobe is deformed at the 6m radial direction. This is the directivity noted by JA7UDE.

This situation can produce many effects, but for me the principals are:

1.- The antenna works randomly, It depends on the installation place, mounting hardware, coaxial cable, etc, etc...

2.- The polarization of the antenna is also random: Vertical at the radial direction, a mixture of vertical-horizontal at the others...

3.- A dipole without a balun makes the coaxial cable (and mounting hardware in this case) to radiate. This is a real problem!

As a experiment, I replaced all the antenna radials with full size quarter wavelength 50 MHz radials with the hope to convert it to a real ground plane antenna. The radials were made with aluminum tube, a screw and a nut. The total length was 145 cm. More details at the next image:


The new radials in detail. This is only one of the multiples choices we have to make them. You can also tweak the antenna tunning adjusting their length. Make sure all three radials have the same length.

Results were much better than I could never expect. The SWR curve is now the one you can expect from a 50 MHz groundplane antenna: 1.00 at 51.080 and 1.4 at 50.000 and 52.000. But for me, the main advantage is the antenna now receives exclusively vertical polarization. This is a great advantage when you are located only 40 Km away from a 250 KW TV channel 2 transmitter!!! The previous TV noise of 9+ is now reduced to S1-S2, and now some real weak signal can be heard, like meteor reflections and multi-skip Es.

No changes were noticed in operation and performance on 2m and 70cm. Just as before the modification.


The modified V2000.

If you have this antenna, and you are not happy with its performance, try to put a real ground plane as I described here. Its cost is under 15 euros and it works much (and much is much) better than the counterpoise.

Miguel A. Vallejo, EA4EOZ

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Svar til #1:
Hej
44 meter er ret langt på 6 meter, men det er muligt at få et godt kabel, med lavt tab.
Hvis du bruger et dårligt kabel, er det en god ide at bruge en forforstærker i masten. Støjtallet forringes lige så meget, som der er kabeltab fra antennen til modtageren. På sendersiden kan man "blot" øge effekten.
Husk at samlinger også giver tab.
Du er på en frekvens, hvor det kan betale sig at bruge et GODT kabel med lavt tab. Så får du både kraftigere udstrålet effekt(ERP), og modtager bedre.

Svar til #9:

Mange tak for god information :-)

Svar til #1:
hejsa alle sammen 1000 tak for alle de gode svar