My Diamond X510NA 2M/70CM Antenna

Last week I managed to get a Diamond X510NA antenna for free! The only issue was that I had to go and retrieve the antenna off the roof and also remove another antenna which I also got to keep. Not sure what the other antenna is but my focus is on the Diamond X510NA. This is my first “Commercial” VHF/UHF antenna. All my previous antennas were home brews which performed just great.

When I got the antenna down, nature has taken it’s course and there was corrosion of the visible metal parts and the white lacquer coating is gone exposing the fiberglass tube. However the tubes were still intact and the copper inside looked great for the most part

In this closeup you can see the minor issues that nature caused.


I was determined to get this antenna looking and performing like it was new.  So I went to the hardware store to look for plastic spray paint  and rubber foam strips for sealing  joints around doors to keep drafts at bay.

Here is a photo with the Rubber foam stripping rolled around where the old foam was. I am doing this to prevent the actual antenna from rattling around inside the tubing.

I designed a bracket to use for the roof  installation. The straps will be made out of 14ga (.074″) stainless and I already acquired a 1.25″ I.D. galvanized pipe and had it powder coated white to match the rest of the antenna. I don’t want any rust up there.

Here is the finished antenna. I mounted it to the deck with zip-ties to make sure the antenna works before going onto the roof.

Here is another angle of the antenna. The joints and feedline were taped with “X-Treme Tape” which is a silicone based
tape that will make a watertight seal. I also used “Undercoat” rubberized spray where the radials are mounted to prevent any more corrosion to the base.

There is a night and day difference compared to my home made antennas. Even though it’s 5ft off the ground and the huge aluminum siding wall right next to it, I am hitting repeaters that I never could hit before. Can’t wait to get this up on the roof.


8 thoughts on “My Diamond X510NA 2M/70CM Antenna”

  1. Any chance you have the capacitor values that are in the Diamond X510 antenna?

    All the best,


    1. I am sorry. I should have taken more detailed pictures. On one of the photos it look likes a brown ceramic disk cap with a black colored tip and the letters 20 right below the black??? There is also some letters that I can’t make out below the 20. If I should take the antenna down for any reason, I will post the info. Ty for reading

  2. I have one that I cannot get the VSWR down on but the caps are 2 PF each in series. Perhaps you can tell me the overall length of the copper inside?

  3. Thanks for posting this. I’m trying to decide what impact this length of antenna (17′) will have on my 1 storey bungalow in a residential area.

    I would suggest not using more than about 35W continuous into this antenna unless you upgrade the first 2 capacitors as they are only 500v ceramics.
    Values are 2.5pf (feed to ground) and 7.5pf feed to coil tap @ 3t.
    Middle element series caps are 2pf each.
    Elements are brass.

  4. Just interested why you feel you can’t run more than 35w into this antenna when the first few capacitors are rated at 500v G7WHK.

    Assuming the system is subject to a 50ohm resistive load, the voltage across them should only ever reach 41 Volts when driven with 35 Watts.

    But what about a high SWR you ask? Once again, assuming a purely resistive mismatch, when driven with 35 watts you’d need a SWR of 142:1 at the capacitor to induce 500v across it. Thats assuming no other system losses, and obviously a purely resistive load.

    Now I know there is always going to be a complex impedance present, causing voltage and current to be out of phase, but I can’t possibly imagine a situation whereby there is an impedance mismatch anywhere near what would be required to destroy the capacitor with 35 Watts of power.

    I’m no expert – is there something I’ve failed to take into account?

  5. @ VK3HXT / VK3BL
    A tuned antenna comprises an inductor and a capacitance and has an impedance.. not a resistance.
    A power of 1 watt will produce a 10 volt peak voltage (7.07v RMS) into 50 ohms. An even higher voltage would be present further away from the feedpoint as the impedance reduces.
    So if 50 watts was passed.. the matching capacitors rating of 500v would be exceeded.

    Have a read of the paper on Equivalent Voltages & Powers in a 50 Ω System

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