Possible tri-band antenna identity question

[Techman]

I was given this aerial the other day and was told it was possibly a tri-band, thought to be 6, 2 & 70. I think it's fairly old and only has one of its three half meter long ground planes and none of its mounting components. It's about 7' long and measures open circuit across its 'N' (not PL) connector, so seems to be a non-DC grounded type - unless there's a fault, of course. Does anyone recognise it? I've looked at a few on-line images, but not found any direct comparisons.

[Jon_G4MDC]

Something like a Diamond V2000. There were many copies.

I've been inside one and the element is DC grounded so static bleed will happen. The input is fed through a capacitor and that is why
there is no DC continuity at the feedpoint.

[Richard675]

If you have all three radials and they are the same then it looks like a 2m/70cm white stick.

If it covered 6m as well one of the three radials would be loaded.

[GMB]

If it covered 6m as well one of the three radials would be loaded.

NOT CORRECT.

I have a triband aerial that looks very like that with simple radials.

[Techman]

Thanks for those pointers chaps.

I had briefly looked at the Diamond antennas, but dismissed them, as they seemed to have a join in the fibreglass tube half way up and I'd assumed that all three ground planes were the same, whereas this one is all in one piece and I'm now thinking that one of the ground planes may have been a loaded type. However, now you've said Diamond V2000, it's given me something more definite to go on and I've taken a more in-depth look at this model and it seems that some were made all in one piece, particularly one that was taken apart by someone on the 'net' with pictures and dimensions and a circuit which I've posted below - it's not an official circuit, but one drawn out by the person who took the aerial apart. I can now see how the DC grounding works with the capacitor coupling to the feed as said above, hence the meter reading of O/C that I noted, leading me to originally think it was a non-DC grounded type. The overall length officially quoted for this antenna is longer than the one I've got here, but that's likely because it's including the mounting hardware.

[Jon_G4MDC]

That's close to what I found when I disassembled one. It's incomplete though.
There are two more capacitors (13J 500V in series) on a board that sits between the folded elements inside the tube.

This one was constructed in a single piece fibre glass tube.

[Techman]

Thanks for those images, Jon. I've now reviewed all the images that chap posted on a website that I found earlier (I saved the images for reference, there were 10, but didn't save the link, although should be easy enough to find via a search) and one of them (posted below) shows exactly what you found. It's looking like it's likely to be an early Diamond V2000, or a copy of it, rather than the mentioned White Stick.

[Jon_G4MDC]

It would be good to find that.

The antenna I posted is doing rather a lot of work. It supports 1x6m, 1x2m and 2x70cm repeaters at Amersham and that refurbishment was Sept 2012. I took off the loaded counterpoise and gave it a full length one under the mounting boss. It took away the squinted polarisation on 6m and made it (hopefully!) pure vertical.

[Techman]

Interesting regarding the counterpoise modification - I've only got one ordinary ground plane, so I now suspect that one of the missing ones is a 'loaded' type. I'll be seeing the chap that it came from in the near future, so I'll ask him a bit more about the history of this antenna and if the other bits are just 'mislaid', or gone for good.

Seeing as I've now used two images belonging to someone else, it's only right to link to the source, so I've looked in my browsing history and found the site - linked to below:-
https://ea4eoz.blogspot.com/2015/09/v2000-teardown.html

[Jon_G4MDC]

Found a picture of it under test...

You can see the 6m counterpoise to the left attached by jubilee clips. It's ~4mm stainless rod 1.5m long.
I did eventually give it a 3rd radial to match the two that can be seen here.
The old 6m position was empty at that time...thinking on it I suppose I must have the loaded one somewhere. I will look.

What I was debating then, and to an extent I still am, would there be an advantage from a choke balun on the feeder?
I suspect it's more prone than it could be to 6m noise conducted up the feeder from Switching PSUs and Computers located below.

[Restoration73]

This version was also very popular - and works well;

https://www.nevadaradio.co.uk/wp-con...structions.pdf