Diamond V2000A cap values

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Diamond V2000A cap values

Postby VK7HH » Sat Feb 06, 2016 3:16 pm

I have acquired a Diamond V2000 (Japanese model) which covers 50-52MHz.

Does anyone have a V2000A (U.S. version) which covers 52-54MHz?
If so, what capacitor values are used on the loading coil? Remove the grub screw and slide the bottom section out. There's about 4 ceramic caps.

The counterpoise radial length on the Japanese version is about 22.5 inches. at it's shortest length.
I may put full length radials on as detailed here -
http://ea4eoz.blogspot.com.au/2012/09/m ... 0-and.html
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Re: Diamond V2000A cap values

Postby VK1JA » Sat Feb 06, 2016 7:12 pm

Hi Hayden,

I have a GP-15 that I bought from Andrews Communications which I believe is the equivalent to a v2000 (it actually came with the v2000 instructions).

I've been tempted to do the mod that you linked to, I'd be very interested to hear how you go if you do do the mod.

Regards

Jayson
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Re: Diamond V2000A cap values

Postby VK7HH » Sat Feb 06, 2016 7:17 pm

Hi Jayson,
It's interesting as the "Comet" version of a GP-15 is marketed as a 5/8 on 6m. I assume the Andrews one is just a copied V2000, or a "C-Loaded" half wave...

Yes I don't have all the bits around here to make radials today, I think that may be a job for during the week.
I did briefly find some old fencing wire today that was about an inch shorter than the counterpoise radial that comes with the Diamond. I put that on and was getting a respectable match at 52.5MHz of R=62, X=0.

Hayden
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Re: Diamond V2000A cap values

Postby VK1JA » Sat Feb 06, 2016 7:27 pm

That's interesting!

My main thought was to broaden the bandwidth, hopefully.

As standard, the GP-15 I have doesn't have much bandwidth on 6m - 50.100-50.300 only. Once I take it up higher the swr rockets up. During the week a VK7 repeater was coming in at +60dB and I couldn't work it because the swr was off the scale up at 52Mhz, if the mod gives me a reasonable swr up at 52-54Mhz and keeps 50Mhz usable it'll be totally worth while !
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Re: Diamond V2000A cap values

Postby VK2EFM » Sat Feb 06, 2016 7:54 pm

A silly aside question, but how can a 2.4m long antenna be a 5/8 on 6m, which is 3.75m ;)
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Re: Diamond V2000A cap values

Postby VK7HH » Sat Feb 06, 2016 9:22 pm

VK2EFM wrote:A silly aside question, but how can a 2.4m long antenna be a 5/8 on 6m, which is 3.75m ;)


Base loaded perhaps?
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Re: Diamond V2000A cap values

Postby VK2GFR » Sun Feb 07, 2016 6:54 am

VK7HH wrote:
VK2EFM wrote:A silly aside question, but how can a 2.4m long antenna be a 5/8 on 6m, which is 3.75m ;)

Base loaded perhaps?


A phasing section, somewhere towards the top of the antenna?
Maybe of coax sections?
Never owned a commercially made antenna for any of my bands on vhf/uhf.
I made a j-pole (for 2mtrs) from the design in the RSGB Vhf Uhf Manual, which offered a lower angle of radiation & slightly more gain.
From the original antenna design was a phasing section, simply a bent up piece of 1/4 wave length tube between original to an extra 1/2 wave length at the very top.
Now days the technique is to wrap the phasing section around a non-conductive medium (lexan) of which both "ends" physically meet in the middle.
Perhaps that is how it might be done in the 2 antennas you speak of?

BTW my j-pole on 6m is 4.5mtrs long, yes it might be misconstrued for a jousting pole... but it works & no it didn't cost me $200.00 either.
(The Castle movie) :D
Mark, VK2GFR
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Re: Diamond V2000A cap values

Postby VK7HH » Sun Feb 07, 2016 8:29 am

Slightly off my original topic but...

I successfully managed to convert an old Stationmaster MK1 to a 5/8 on 6m. I documented it here for those that are interested -

http://hh.vk7.com.au:82/blog/index.php? ... id_post=20
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Re: Diamond V2000A cap values

Postby VK1JA » Sat Feb 13, 2016 12:44 pm

Hi Hayden,

Just as an update, I replaced the 3 radials (one of which is loaded for 6m) on my gp-15 with homebrew elements, each being 145cm long and the swr over 6m is much broader !

Using the standard radials I could only use 50.000 to 50.300 without the inbuilt tuner of the TS-2000. And up at 53.000 the swr was so bad that even the inbuilt tuner wouldn't tune it...

Now with the homebrew radials, 50.000 to 51.500 is under 1.3:1 (yes, that's 51.500) , rising to 3:1 at 53.000. While it's high at 53.000 the inbuilt tuner is happy to tune it now, and for the amount of times I'll be using it up that high it doesn't really matter, but at least I CAN now use it for repeaters etc.

I'm particularly happy how the bottom part of the band is all under 1.3:1 - that's where most of my play time is spent :)

Hope it helps.

Jayson
Attachments
6m radial mod 1 small.jpeg
gp-15 radial mod
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Re: Diamond V2000A cap values

Postby VK2EFM » Sat Feb 13, 2016 7:35 pm

Hi,
I also put decent radials on the 6m antenna. I have a V2000 and put 3X150 cm radials on it and the VSWR was as follows:
50 3.0:1
51 2.0:1
52 1.0:1
53 1.4:1
54 3.0:1
I haven't tried tuning it and the antenna was set up for 52 to 54 MHz.
I used solid 6mm Aluminium rod and tapped M5 threads in the ends to screw onto the antenna base.
Allan
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Re: Diamond V2000A cap values

Postby VK7HH » Sun Feb 14, 2016 7:34 pm

VK1JA wrote:Hi Hayden,

Just as an update, I replaced the 3 radials (one of which is loaded for 6m) on my gp-15 with homebrew elements, each being 145cm long and the swr over 6m is much broader


Hi Jayson,
I did the same last week. I made three new radials from 5mm solid rod, and threaded the end with M5 x 0.8?

I put the antenna up a short height above ground, and it appears that the antenna is now usable at 52.5MHz. The radials were 1.43m long. I have not yet tried properly, just the reading on the MFJ was now showing a much better sweep up there.

I think I still need to shave a bit off the radials somewhat as the lowest appears around 52MHz.

Good to see you had good success with yours

Regards
Hayden
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Re: Diamond V2000A cap values

Postby VK2ZIW » Thu Feb 25, 2016 5:07 am

SSB on 50.1 MHz Horizontal and FM on 53MHz Vertical.

Two antennas. Here, 4el beam and 5/8.

5/8 is a CB ground-plane, shorter GND radial pieces were added to the vertical => 5/8 on 6m.
Matching coil under base.
It was flimsy so I added guy strings, vertical to radials then back to the pole underneath.
(Venetian blind cord) Has been up 20+ years. Works well. Band scanning 24x7 with VX-5R h-h.

Alan VK2ZIW
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Re: Diamond V2000A cap values

Postby VK7HH » Thu Apr 14, 2016 11:44 am

Further to my earlier post, I cut my radials down a bit more, so now return loss is lowest at 52.5MHz at 20dB.

14dB bandwidth is about 1MHz.

I think I'll experiment some more with this antenna and see if I can shorten the radiator and/or play with the cap values a bit to bring it closer to the top end of 6M.

Hayden
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