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SO2R Genius XL and External Band Pass Filters

Reggie
Reggie Member ✭✭

If I use a Flex 6600 with a PGXL and Genius XL in a SO2R configuration, are external Band Pass Filters required for each antenna or are they included on the PGXL and Genius XL?

Thanks,

Reggie

N3OP

Best Answers

  • Reggie
    Reggie Member ✭✭
    edited June 18 Accepted Answer

    Len,

    Thanks for the response. Sorry for the confusion. I was referring to the Tuner Genius. I figured I had to protect the receivers from overload. Dave, Wo2X did a Quick Start video on the Tuner Genius XL on YouTube and showed a diagram of a SO2R setup using the Flex 6700, PGXL, Genius Tuner XL, and the Antenna Genius. There was no mention of using external filters to protect the radio, so I though Flex included the Band Pass Filters in the Tuner based on the diagram. The video can can be seen here: FlexRadio Tuner Genius XL - Quick Start Video - YouTube


    Here is the diagram:


    73,

    Reggie

  • David Decoons, wo2x
    David Decoons, wo2x Member, Super Elmer Moderator
    Accepted Answer

    The info “with bandpass filters” was taken from Flex documentation. As Len stated, the free space separation of the antennas will determine if additional bandpass filters are required.

    The tuner when in circuit will act as a bandpass filter to some degree. Best is to run the calculation sheet from the link Len provided.

    73

    Dave wo2x

Answers

  • KD0RC
    KD0RC Broomfield, COMember, Super Elmer Moderator

    Hi Reggie, Not sure what Genius XL you mean (Antenna Genius, Tuner Genius), but I think you are after how to protect your receiver on one band when transmitting on another with high power. The Flex 6600 has 7th order bandpass filters for > 50 dB of rejection of out of band signals on the contest bands. Even with this level of protection, you still need to watch out for how much signal you dump into the receive antenna while transmitting. Here is a worksheet that you can use to determine if you need additional rejection, or different antenna placement for your SO2R operation.

    https://www.flexradio.com/documentation/flex-6000-fdx-power-calculation-worksheet/

  • KD0RC
    KD0RC Broomfield, COMember, Super Elmer Moderator

    Hi Reggie, Yep, I saw that video. Dave labeled the tuner as "... with band pass filters". I got this from the TGXL user manual:

    Tuner Genius is electrically implemented as a pi‐network tuner with three variable elements; a series inductor with two capacitors to ground: one at the input and the other at the output. A pi network is ideal for matching the relatively low 50Ω impedance of a transmitter and relatively high and unknown impedances antenna system present for a current operating frequency. Furthermore, because the matching circuit also forms a low‐ pass filter, it provides beneficial harmonic suppression beyond that provided by the exciter and amplifier.  

    So I don't think there is a set of bandpass filters in the TGXL, but like most pi-network tuners, it provides a low pass function when tuned to resonance.

    If you get time, fill out the full duplex power calculation worksheet. That will tell you if your particular SO2R set up is going to be OK, or if you need more filtering, less power or more antenna separation.

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