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Controlling Two BPFs for SO2R with 6700

Eric GruffEric Gruff Member
I've seen a lot of similar questions and answers, but not this one.

I am using my Flex 6700 with two FilterMax4 bandpass filters. Until now, I manually select the bands as I change Slices A and B (the two SO2R bands I'm using). I own a Microham StationMaster as well as a ton of cables and boxes, but it seems the only way to control each FilterMax4 individually is to buy or build a second band decoder.

It would seem that I could tell the StationMaster what band both TX slices are on via USB, and program the 12 V relays on the back to switch both filter units accordingly, but it doesn't seem possible to pass both frequencies effectively to the SM. The Flex can send them, but the SM won't know they are two separate radios. I also have all the software to generate and bridge virtual serial ports, etc if that is a way to achieve this.

Before I drop more money on another SM, has anyone solved this problem? It sure seems like something that can be done. Big contest stations seem to be able to switch 147 different antennas to 69 different radios, so why can't I control two fairly simple filters from one radio?


Eric NC6K


  • Andy - KU7TAndy - KU7T Member ✭✭
    edited June 2019

    I use a single FilterMax4 connected via USB from the 6600M but I do not see any reason why this would not work for both ANT outputs. All you need to do is associate the BCD port with the right antenna AND get the levels adapted. I used a single chip that converts the TTL to 12 V.  If you need more info, I can dig it up.

  • MackMack Member ✭✭
    edited June 2019

    There are many solutions to your question. I also own FilterMax IV filters. 

    Here is one solution. Buy two Denkovi USB relays. http://denkovi.com/usb-relay-boards

    These will accept USB commands from the rear of the 6700. Then use the SmartSDR USB Config menu to select the appropriate relays for each band. 

    You can also add an inexpensive band decoder if preferred. https://www.dxengineering.com/parts/ums-bcd-14?seid=dxese1&cm_mmc=pla-google-_-shopping-_-dxese1-_-unified-microsystems&gclid=CjwKEAjw__fnBRCNpvH8iqy4xl4SJAC4XERPbkFKnqCFg83OWeQTwhaM6Y4-24IMR5MNgkCN8JhsXRoCf7jw_wcB

    Either of these solutions are not very expensive. I trust you know how to wire things so I won't try to write all that up. 


    Alpha Team
  • Eric GruffEric Gruff Member
    edited June 2019
    Andy and Mack,

    Thanks very much. Both solutions make sense, and I am familiar with the overall setup. I think I'll go with the Denkovi out of sheer laziness.

    Your help is much appreciated!

    73 de NC6K
  • Bill - W9KKNBill - W9KKN Member ✭✭
    edited June 2019
    I do essentially this with two Array solutions Bandmaster 5s. What's nice about is that the FilterMax units can be driven over ShackLAN.

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