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Thread: Tuning Diamond V-2000 Antenna

  1. #1

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    Default Tuning Diamond V-2000 Antenna

    Hi,
    I have a Diamond V-2000 antenna (70Cms 2Mtr 6Mtr coil on Radial)

    I can connect to a repeater on 70cms 15 miles away on 0.5W, but it is't good on 2mtrs. Is there a way of tuning the 2mtrs while keeping the 70cms good? I have an antenna analyser for 2mtrs but not 70cms.

    Here is a photo of the works, showing the coils 2x grub screws and 1x screw. I assume the 1x screw is there hopefully to tune something?

    Any ideas Camerart.

    V2000 1.pngV2000 2.pngV2000 3.png

  2. #2

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    To be honest, on VHF the gain figures are always a bit questionable - they claim just of 3dBd at 2m, with a bit more at 70cm - I suspect you're already at this point. The sections inside are pre-cut so the only thing that the grub screws control is the matching to get a lowish VSWR, I don't think you're going to improve the performance and probably wreck the VSWR. They're reliable compromise antennas, so not brilliant. I have the 2/70cm version and it's selling point is simple that it's a base station for two bands with one feeder.

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    Quote Originally Posted by paulears View Post
    To be honest, on VHF the gain figures are always a bit questionable - they claim just of 3dBd at 2m, with a bit more at 70cm - I suspect you're already at this point. The sections inside are pre-cut so the only thing that the grub screws control is the matching to get a lowish VSWR, I don't think you're going to improve the performance and probably wreck the VSWR. They're reliable compromise antennas, so not brilliant. I have the 2/70cm version and it's selling point is simple that it's a base station for two bands with one feeder.
    Hi P,
    A friend made me a 2mtr Jpole, which is in the loft, that I use for a local net. I m just getting into repeaters,and need a 70cm antenna, I tried the v-2000 in the loft as mentioned. Neither of them are able to do both jobs. What do you suggest please?

    I am quite happy to mess about with the V-2000. As I said the 70cms gets into the repeater with 0.5W, so I don't mind raising the 2mtr at the expense of the 70cms. Or should I simply start again?
    C

  4. #4

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    Quote Originally Posted by camerart View Post
    Hi,
    I have a Diamond V-2000 antenna (70Cms 2Mtr 6Mtr coil on Radial)

    I can connect to a repeater on 70cms 15 miles away on 0.5W, but it is't good on 2mtrs. Is there a way of tuning the 2mtrs while keeping the 70cms good? I have an antenna analyser for 2mtrs but not 70cms.

    Here is a photo of the works, showing the coils 2x grub screws and 1x screw. I assume the 1x screw is there hopefully to tune something?

    Any ideas Camerart.

    V2000 1.pngV2000 2.pngV2000 3.png
    You are asking too much from the Diamond V-2000 antenna..

    The two variables are the coax you use between the antenna and the radio and the antenna height..

    Because we can't look at the path loss, there is no way for sure to know what you are trying to talk thru, but for best results you need that antenna at least 40' off the ground..

    With 50' of LMR 400 - your loss at @ 440 Mhz would be a loss of about 4 db, and you can't use a PL connector for 70cm, because there is a impedance bump around 300 mhz that throws off the scale of loss.

    Your best bet is to get a better transmitter that produces more power...

  5. #5

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    Look at the design. The usual limit for two ¼ waves, or a ¼ wave and a ¾ wave, for example is about 3dBd - less a bit of matching loss - which is what these adjustments do. They cannot add gain, this is a function of the total design. Realistically, to get another 3dBd, the effective length of the antenna needs to double. If it was a case of tweaking the coupling screws, Diaond would have done it, claimed extra gain and increased the price. Like sixmeters says, you're expecting too much.

  6. #6

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    Quote Originally Posted by Sixmeters View Post
    You are asking too much from the Diamond V-2000 antenna..

    The two variables are the coax you use between the antenna and the radio and the antenna height..

    Because we can't look at the path loss, there is no way for sure to know what you are trying to talk thru, but for best results you need that antenna at least 40' off the ground..

    With 50' of LMR 400 - your loss at @ 440 Mhz would be a loss of about 4 db, and you can't use a PL connector for 70cm, because there is a impedance bump around 300 mhz that throws off the scale of loss.

    Your best bet is to get a better transmitter that produces more power...
    Hi S,
    Ok, thanks.
    I'm a fan of low power.
    I've just ordered a handheld Beofang. Using a friends, I've got into this repeater with it. Let's see if it works from here?
    C.

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    Hi P,

    Ok, thanks, I'll give it away.

    C.

  8. #8

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    Quote Originally Posted by Sixmeters View Post
    You are asking too much from the Diamond V-2000 antenna..

    The two variables are the coax you use between the antenna and the radio and the antenna height..

    Because we can't look at the path loss, there is no way for sure to know what you are trying to talk thru, but for best results you need that antenna at least 40' off the ground..

    With 50' of LMR 400 - your loss at @ 440 Mhz would be a loss of about 4 db, and you can't use a PL connector for 70cm, because there is a impedance bump around 300 mhz that throws off the scale of loss.

    Your best bet is to get a better transmitter that produces more power...
    Hi S and P,
    I had a rethink with my last answer!
    I am not good at calculations, but maybe more logic.

    With V-2000, the feeder has a PL to 'N' type converter, also a PL on the rear of the FT817, @434MHz and 0.5W it will switch on 1x repeater 35 miles away and another 15 miles away, while in the loft.

    @145MHz the SWR (Is this the same as VSWR?) is 4. This seems a bit high for a manufactured antenna to me, maybe there's a fault?
    C.

  9. #9
    Super Moderator pmh's Avatar
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    I know somebody who had a 6:1 SWR on a V2000, it turned out they didn’t connect the inner of the top section to the inner of the bottom section, before sliding the 2 sections together, despite this clearly being shown in the accompanying instructions.

    We recently put one up at the club and it performs very well.

    If you don’t have the instruction leaflet, then do a google search. Then check to see if the V2000 you have is correctly assembled. SWR should be around 1.5:1.

    Kind regards,



    Phil

  10. #10

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    Quote Originally Posted by pmh View Post
    I know somebody who had a 6:1 SWR on a V2000, it turned out they didn’t connect the inner of the top section to the inner of the bottom section, before sliding the 2 sections together, despite this clearly being shown in the accompanying instructions.

    We recently put one up at the club and it performs very well.

    If you don’t have the instruction leaflet, then do a google search. Then check to see if the V2000 you have is correctly assembled. SWR should be around 1.5:1.

    Kind regards,



    Phil
    Hi P,
    I found the manual, but it is the American version.

    If you check the image at #1 (V2000 2.png) , at the joint between top and bottom sections, there is a screw, which is tight. Next to the screw is a capacitor too, along with Capacitors all along the antenna.

    As it looks like there is a fault, what things should I check for?

    C.

  11. #11
    Super Moderator pmh's Avatar
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    Check this pdf and look at figure 1 and figure 2:-

    https://www.diamondantenna.net/pdfdocs/V2000A.pdf

    It’s the connection in figure 2 that is sometimes forgotten.

    Kind regards,



    Phil

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    Quote Originally Posted by pmh View Post
    Check this pdf and look at figure 1 and figure 2:-

    https://www.diamondantenna.net/pdfdocs/V2000A.pdf

    It’s the connection in figure 2 that is sometimes forgotten.

    Kind regards,



    Phil
    Hi P,
    Thanks for the PDF. As mentioned in #10, it is the American version.

    Also in #10 I said the screw image (V2000 2.png) @ #1 is tight. This looks like the connection you are referring too, is this correct? Is this the connection that would give a good SWR at 70cms and a bad SWR @ 2Mts?

    Yesterday I removed all of the screws and cleaned the metal before connecting again, this appeared to improve the SWR a little, but now the antenna it in the garden (Not in the loft).

    What would the effect be of faulty capacitors?

    C.
    Last edited by camerart; Thu 16th Aug 2018 at 09:04.

  13. #13

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    Unless it was stuck by lightning, the capacitors aren't bad.

    If it was struck by lightning - you wouldn't care anyways, because all you would have left is fiberglass shards all over the yard.

    The antenna needs to be about 10 feet above the main roof of the house to radiate it's best, even higher for a 1 story house - 30 - 40'...

    The 2m part of the antenna is tuneable by the tuneable whip at the bottom of the antenna, the longest radial.

    With good coax - multiples of 1/2 wavelengths of the frequency desired on 440 ish mhz.. The antenna should show a fairly flat VSWR - anywhere from 440 - 450 Mhz. If yours shows a high swr - probably means that there is metallic objects too close to the antenna - hence putting it in the loft as you call it - isn't an optimum location for any antenna.. My V2000 has been in multiple locations since 2012 and I never had a single problem with it as long as you follow some simple rules.. Always use the lowest loss coax you can BUY. Always use the maximum amount of power to transmit, use the lowest amount of power to tune.
    Don't use RG 8 coax or 213 and don't use old coax and most definitely don't use Mini 8 for 70 cm...

  14. #14

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    Quote Originally Posted by Sixmeters View Post

    The 2m part of the antenna is tuneable by the tuneable whip at the bottom of the antenna, the longest radial.
    Hi S,
    All points noted. I can address some of them later.

    I'm not going to be able to put it as high as you suggest as I've decided not to go up anymore ladders, apart from the one to the attic, as I also sometimes call it.

    Regarding the tuning, as above. I thought the longest radial with the coil on it was only for tuning for 6Mtr, but I'll try it and report back.
    Thanks.

    Thanks, C.
    Last edited by camerart; Fri 17th Aug 2018 at 09:06.

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    Hi,
    I checked the capacitors, 1x between the connection point and 5x at the base and they all showed open circuit. I checked my chinese capacitor tester with a known cap and it read ok, but it does seem suspicious.

    Here's a photo of the base Cap and values.

    C
    Attached Images Attached Images

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    Super Moderator pmh's Avatar
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    The manual being American makes no difference to general assembly. The original pictures you posted are of little value to assist.

    The adjustable radial is, indeed, for the 6m band.

    If you used a capacitance meter to check the capacitors, then you should get a reasonable reading, though the exact value will be affected if components are tested in circuit. You could drop one showing open circuit and test it as an isolated component.

    I doubt all capacitors will have gone - you could always try changing them as a precaution if you are still unsure they are ok.

    My X50 is on the apex of the house, clearing the roof by 3/4 of a metre max, and performs perfectly.

    Close proximity of object will affect SWR to a different level on different bands.

    I did hear a tale where one owner put too much power through on 6m, taking out the capacitor, which affected the aerial across all 3 bands, but you should be able to check this.

    Other than the above, I don’t think I can add anything else.

    Kind regards,



    Phil

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    Hi P,

    All snippets of information can be helpful, thanks.

    In the image at #15 the NPO 9J cap which I assume to be 9pF is reading 57pF. Actually 9pF is a very small capacitance, and suspect, I'm going to change it and see what happens.

    C.

  18. #18
    Super Moderator pmh's Avatar
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    I don’t think that is 9j, there appears to be another digit first, though it is hard to see.

    Kind regards,



    Phil

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    Quote Originally Posted by pmh View Post
    I don’t think that is 9j, there appears to be another digit first, though it is hard to see.

    Kind regards,



    Phil
    Hi P,

    I have looked at it through lens and there is something there, which could be another digit, and would make more sense as 9pF is pretty small. The missing digit, is not inline with the K as with all of the other caps.

    Just found an image with one coil and a 7pF cap, so perhaps it is correct. Let's change it and see what happens.

    C.
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  20. #20

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    Hi,
    I changed the 9pF cap for a 10pF, and the result is the same SWR 4
    C.

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