The Diamond V2000A is a fantastic antenna on 2m and 70cm, but it has a steep SWR parabola on 6m.
I found this website, describing that 145 cm is a much better length for the radials. This guy appears to be European, and is improving a V2000 antenna (not V2000A). He used a m6 bolt and some aluminum tubes to create the radials.
Wimo also sells 145cm replacement radials, which become very costly to ship to the US.
The V2000A appears to have a little different measurements. I took a radial to the hardware store and discovered it uses a #10-32 machine screw thread (standard, not 10mm).
I could not find any aluminum tubes, but I did find a 6 foot long 3/16" rod, along with a 10-32 hex die.
And even though 3/16" is not exactly the same as #10, the die threaded it easily.
Starting with the full 6 foot length rods, I measured SWR with a Nano VNA at several lengths down to the 145 cm mentioned in the instructions (which is electrically 1/4 wave at 6 m). And the results were interesting.
For reason’s I really dont understand, the antenna liked 6 foot better than 145cm. The rods are only $7 each, so this ended up being one of the more affordable radio experiments I have done.
Here it is up in the air with a new set of 6’ radials. Hopefully those long whippy things stay where they belong.