Trying to get answers on Full duplex HT for satellite

Discussion in 'Satellite and Space Communications' started by KE7GVK, Jun 25, 2015.

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  1. K3RLD

    K3RLD Ham Member QRZ Page

    Yes, that would work. But not sure what you mean by "non-duplex version of the arrow".

    Do you mean "no duplexer"? If yes, then YES. The transmit radio will connect direct to the transmit yagi feedpoint. The recieve radio will connect direct to the receive yagi feedpoint. Two radios, two lengths of coax, and two physical antennas.

    Note that this could still be a problem when operating a V/U satellite like SO-50 or LilacSat-2. The Rx frequencies on these satellites are very close to harmonics of the Tx frequency, so desense is likely. But many have solve this by using a duplexer anyway (for just the downlink).
  2. W5PFG

    W5PFG Premium Subscriber QRZ Page

    To connect a single VX-8DR to an Arrow antenna, you need a diplexer.

    If you connect the VX-8DR and another radio to an Arrow antenna, you need two feedlines. One from each radio to each feedpoint on the Arrow. The Arrow has two feedpoints: one for 2m, and one for 70cm.

    The diplexer is essentially a cable harness that takes the two feedpoints of the Arrow and brings it to one feedline for a single radio. It has filtering to separate the 2m/70cm signal.
  3. N2DJS

    N2DJS Ham Member QRZ Page

    Yes, buying the Arrow without the duplexer is what I was referring to.

    Can you elaborate on the 2nd issue? Do you have a particular duplexer in mind outside of $60 arrow one?
  4. K3RLD

    K3RLD Ham Member QRZ Page

    I use the MFJ 916B. They are $25. Simply put it inline on the UHF side (I think, it's been a while since I tried using two radios for full duplex).
    AD7DB likes this.
  5. W5PFG

    W5PFG Premium Subscriber QRZ Page

    Roy is describing using his MFJ-916 as a filter for one side of the transmit/receive equation. This is common.

    The other use of the MFJ-916 is to take both the 2m and 70cm feedpoints from the Arrow and bring it to one feedline to go into a preferably full-duplex-capable (semi ok) radio.

    You can actually save a little money from buying the stock Arrow diplexer which is limited to 10 watts. The MFJ is not handicapped to HT-power levels. The only real advantage to the Arrow diplexer is it's very light and portable, great for one HT use.
  6. WD9EWK

    WD9EWK Ham Member QRZ Page

    KJ5Z, KS1G and WE4B like this.
  7. KS1G

    KS1G Ham Member QRZ Page

    You have 1/2 of my 2HT FM setup; other half is a VX5. I use the Arrow without the duplexer; VHF into one radio, UHF to the other. Which one depends on what you have for headsets, speakermikes, etc... For Mode VU (AO-27, SO-50), you may need to protect the UHF side from desense from 2M; K3RLD described how he does it. You could try VX8 as the RX for 70cm as well and Baeofeng for TX and see if there's any desense. If not or acceptable, you don't need the diplexer.

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