What adapter (bullets) & Hardware must I buy to connect LDF4-50 Heliax to this BIRD?

Discussion in 'VHF/UHF - 50Mhz and Beyond' started by GM4BRB, Oct 13, 2014.

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  1. GM4BRB

    GM4BRB Ham Member QRZ Page

    1-5/8in UnFlg? (Unflanged)

    It's on my Bird 8861 (8860 series of 1.5KW) Oil filled Dummy Resistor.


    I'm only an amateur not a Broadcast Pro.

    BIRD 8861 (Load Resistor, 1.5kW, 1-5·8in UnFlg).jpg
    My Bird 8861. The 8860 Series - some have 'QC' (Quick-Change) 4-screw adapters, this don't I think.

    A view of it on the shelves.

    And I ain't no plumber neither, nor ...
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    I have exactly the same load with a type N connector on it.

    They are changeable, but not "quick change" with four screws. You have to unscrew the whole flange at the clamp.
  3. AA3EE

    AA3EE Ham Member QRZ Page

    That's a standard 1-5/8" EIA slip fitting, I have the same connector on my load. You can look for a slip to flange adapter, and then a 1-5/8 flange to N adapter (sometimes called a cone), or if you're really lucky, you can find a slip to N adapter. I have a few anchor insulators (aka bullets) if you need one, but I'm not giving up my adapters!

    I've never seen a slip rigid to Heliax connector. Heliax to standard EIA flanges are pretty common, even up to 6", but they tend to match sized directly (1-5/8 Heliax to 1-5/8 flange, etc).

    Good luck
    Dave AA3EE
  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Easier to find a new clamp-on flange with an N connector or something more common for amateur use.

    Mine came with one, but I see them at the Swap Meet pretty often for $25-$30 or so, because that particular load is very common and popular.

    Mine has a "calibration" tag on it from Hughes Aircraft Company, dated 1975.:p That was a long time ago, but I can't imagine what can go out of calibration in a connector!
  5. GM4BRB

    GM4BRB Ham Member QRZ Page

    I understand that it requires a FLANGED to Heliax adapter and mine is the less common 'unflange' type.

    Thanks, can you send me one? That's the bullet for 1 5/8th inch. Of course, I'll pay P&P.

    There's a geezer on eBay.com (US) offering 3 of them for £0.99p but won't send to the UK. Even if I get that little part, I think there's a lot more yet to do.
    I can get the local metalwork shop (Tig, Mig, CNC) to knock something up. They're getting all my metal/antenna work. It could work out easier in the long run? They can certainly build anything I ask them too but it won't be the same if I don't have the original designs.

    I'll contact BIRD helpline.

    I'll keep asking here and now, if anyone's got the "1-5/8 flange to N adapter (sometimes called a cone), or if you're really lucky, you can find a slip to N adapter."... parts, which if you're happy to part with, then let me know, will you!? I have real money, the paper stuff.

    73 de Graeme.
    Last edited: Oct 14, 2014
  6. AA3EE

    AA3EE Ham Member QRZ Page

    Yes, getting a bullet will be the easy part. Machining a flanged adapter would be quite a bit of work and needs a fairly large chunk of brass or copper. All you really need is a few tubes to match the diameters, some tube or machined rod to mate the inner tubes, and a flat plate to mount a connector. Skip the whole flange bit. I'll try to find my adapter and post a photo over the weekend. I think most of my parts are for flanged coax, which has slightly different dimensions. Is there a local TV or FM station you could get friendly with? They may have some parts in the junk (junque for you I guess) box.
  7. WA9WVX

    WA9WVX Ham Member QRZ Page

    But Amateur Radio Operators are resourceful at finding a solution to there problems. When you mentioned that you are not a plumber / Drain Surgeon ... I happened to think, "hey that's an idea" if only I knew the Outside Diameter of that 1-5/8" termination connector on the Bird Dummy Load perhaps there's Copper End Cap that might fit the termination connector and then mount a "N" Type connector in the center of the Copper End Cap. Use small brass tubing between the "N" Type chassis connector center pin and the internal center pin of the terminated load.

    If that doesn't do the trick, then here's BIRD's website http://www.birdrf.com/ Maybe they have an expensive solution.

  8. AA3EE

    AA3EE Ham Member QRZ Page

    They're standard EIA rigid sizes.
    Outer OD 1.625"
    Outer ID 1.527"
    Inner OD 0.664"
    Inner ID 0.588"

    Multiplying by 25.4 for mm is an exercise left for the reader :)
  9. GM4BRB

    GM4BRB Ham Member QRZ Page

    I still would not attempt such a thing without the bespoke BULLET.

    The Impedance of 50Ω has to be preserved accurately and at 1.5Kw (theoretical) if things went badly?

    Last edited: Oct 15, 2014
  10. GM4BRB

    GM4BRB Ham Member QRZ Page


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