1. You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
    Dismiss Notice

Cushcraft PD-2 Power Devider ???

Discussion in 'Amateur Radio Antennas' started by Mudfoot, Aug 2, 2019.

  1. Mudfoot

    Mudfoot Sr. Member

    Joined:
    Jun 17, 2009
    Messages:
    9,324
    Likes Received:
    3,834
    If I was to use a power divider on my Cushcraft 148-20T, would both planes need to be tuned the same? Say, if the flat side is tuned to 144.200 and the vertical is tuned to the upper portion of the band, what will I see at the radio? If I'm transmitting on 147 ish and my vertical SWR is flat, but at 144 ish the flat side is 1.8:1, what will that mean? Or, vise versa, I'm working SSB with a near flat SWR horizontal, but the vertical plane sees that high.... The documentation says I'll lose 3 db, but won't suffer the cross polarization..I'm curios as this will allow one feedline and no switch.

    Never used one, so I have no clue.


     

  2. Captain Kilowatt

    Captain Kilowatt Professional Amateur
    Staff Member

    Joined:
    Apr 6, 2005
    Messages:
    15,725
    Likes Received:
    8,014
    I'd rather use a switch than phase them. The resultant SWR will be hard to predict without knowing the exact impedance of each antenna separately. It should not be tooooooo bad however it will be higher than it is now on H but likely a bit better on V. All the Cushcraft power divider is is a TEE connector and a pair of coax cables cut to the proper length. I made a power divider for my pair of 13B2's out of some square aluminum tubing and half inch copper pipe. The impedance is handy 35 ohms and when each 13B2 is tuned to 50 ohms exactly the combined impedance is also 50 ohms. Works great at least on a temporary setup. Still need to get them on the tower. I had hoped to do that before returning to work but still on vacation now and don't get back until Monday. Back to work on Friday. Maybe my next days off.
     
    midnight special likes this.
  3. Mudfoot

    Mudfoot Sr. Member

    Joined:
    Jun 17, 2009
    Messages:
    9,324
    Likes Received:
    3,834
    Thanks,

    I was thinking of making one to experiment with. The why my tripod mount will be on my house, will be easy to access. I'll be able to experiment and swap out stuff.
     
  4. Mudfoot

    Mudfoot Sr. Member

    Joined:
    Jun 17, 2009
    Messages:
    9,324
    Likes Received:
    3,834
    Captain Kilowatt

    Would you direct feed with both LMR-400UF directly to each element, or consider feeding it with a LMR-240UF jumpers to avoid weight strain? Boom is light and sags enough without cable. I might be able to get the LMR-400UF to hold upward looping force when taped to my tripod, IDK yet. I'm going to do a mock setup on the ground first.

    I want to run the coax straight down and behind the DE's. If I do that, I'll have a tight bend radious to accomplish that. I even thought about putting an 90° adapter to eliminate the bend. I believe the insertion loss of that Rube Goldberg would be negligible.

    Just my typical brain ramblings.
     
  5. Captain Kilowatt

    Captain Kilowatt Professional Amateur
    Staff Member

    Joined:
    Apr 6, 2005
    Messages:
    15,725
    Likes Received:
    8,014
    I would use the smaller cable. Not much loss in such a short run. I will be using LDF4-50 heliax with Belden 8214 phasing lines. The heliax is a tad stiff for that.
     
    midnight special, binrat and Mudfoot like this.
  6. Mudfoot

    Mudfoot Sr. Member

    Joined:
    Jun 17, 2009
    Messages:
    9,324
    Likes Received:
    3,834
    That's what I'll do. Hamfest is tomorrow in Columbus. Likely find everything I need. Next project is to acquire a big 2 meter amp and possibly a nice mast mounted preamp. I should be exact 57' to the boom.
     
    Captain Kilowatt likes this.
  7. BJ radionut

    BJ radionut Supporting Member and 6m addict

    Joined:
    May 9, 2008
    Messages:
    2,389
    Likes Received:
    1,765
    I did same thing on 6m/2m antennas/ beams...used about 15-20ft of Belden 9913 and barreled it to the Andrews 1/2" heliax, after the rotor loop. Plus saves a lot of BS if I want to remove the antennas from tower, cut thru the coax seal and tape on the splice. Lift mast and all out and bring them down. Heliax stays on the tower.:ROFLMAO:
     
  8. Mudfoot

    Mudfoot Sr. Member

    Joined:
    Jun 17, 2009
    Messages:
    9,324
    Likes Received:
    3,834
    A friend of a friend let me use his devider that was part of his stacked beams that blew down. I asked to buy it, but he wouldn't part.

    Anyways, it seemed to work. Highest SWR was 1:6. I measured it and gonna make one to experiment with. Didn't make any contacts as my setup is still on the ground. MFJ wants like $80 for it, which is nuts.
     
  9. Tomaso

    Tomaso New Member

    Joined:
    Oct 11, 2019
    Messages:
    1
    Likes Received:
    0
    If you feed them with a T, the swr curve will look like a W, not a V. There are two dips.

    You would do much better with either an antenna switch, or a remote antenna switch. This way, all of the power is used. Just select the better antenna.

    Tomaso
     
  10. Mudfoot

    Mudfoot Sr. Member

    Joined:
    Jun 17, 2009
    Messages:
    9,324
    Likes Received:
    3,834
    I don't have the antenna up yet, but will be soon. The way it's going to be positioned on my roof, it will be somewhat easy to take down. I intend to try the devider at some time just to compare.
     

Share This Page

  • About Us

    The WorldwideDX Radio Forum was originally established in 2001. We pride ourselves on welcoming Radio Hobby enthusiasts of all types, while offering unbiased, informative, and friendly discussion among the members. We are working every day to make sure our community is the best Radio Hobbyist's site.
  • Like us on Facebook

  • Premium VIP Member

    The management works very hard to make sure the community is running the best software, best designs, and all the other bells and whistles. Care to buy us a beer? We'd really appreciate it!

    Donate to us!