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MPET Beginners Thread

Do you consider yourself at the basic understanding of radio theory or electronics in general? This thread is just for you as it relates to asking ANY questions about the OMARC MPET project.

Here is how we define a beginner:


  • O.K....I'm at the starting line and raring to go.
    So far, this is my basic 'vision' for what I'd like to accomplish in the weeks and months to come:
    Objective: Use the Ritron DTX-142 Programmable FM transceiver module to contract a fully operational 2 meter transceiver that will show all the working parts and can be used as an instructional tool for prospective Hams and 'newbies' like myself to actually see parts of a transceiver that have only been 'words' up to this point.

    By mounting on a plexiglas base with a removable or hinged plexiglas cover the power supply (a 9V battery), all the 'working' parts, the hook-ups to the microphone and speaker, the oscillator, and all the other gizmos will be visible.

    I originally was going to mount the project on a nice piece of wood however, that would not allow viewing of the beautiful 'artwork' on the underside of the board.

    I want to show this project one-day to my grandchildren and perhaps take it into a science class at our local middle school or high school and show students a working amateur radio that they can build themselves.

    For me personally, obtaining the microphone, speaker, battery holder, switches, mounting materials and other 'stuff' will be fun and educational. learning how to solder and use the DB-15 pin connector to actually understand what happens when you push the PTT button or switch to another frequency will be part of the fun for me. Oh...I want a display, probably LCD or whatever, to show what frequency (channel) the radio is tuned to.

    I welcome any ideas, suggestions, feedback, offers of help or just encouragement to get on with this. I'm not sure what type of switches I will need, or wire, or where to borrow or buy a soldering tool, or how to work with plexiglas...or...well you get it.

    Thanks for reading this.

    Take care,


  • I think using an acrylic case might be nice for showing.. Of course this would offer no shielding or grounding capabilities, and not to mention, static,,, but it would look nice and probably be the way to go...

  • Thanks Aaron, good point and you have me thinking...assuming RF grounding is what you are talking about...I've been thinking of the MPET/Ritron project as a 'handheld on a base'...what grounding might I add and how...

    See, I knew I would learn from this project.

    Thanks....take care.

  • Ground is common for the MPET, so the outside of the antenna connector and pin 15 on the DB-15 connector plus the outside of the DB-15 connector is what you can tie to.

    Also if you pass a metal stand off through any of the mounting holes, they will contact ground as well.

    You want to make sure you do not create any ground loops, so I think your "handheld as a base" application will be easy to implement.

    The case you mount it in if you want to limit any external RFI or what the MPET may radiate on its own is probably best to be metal. The case will then function as part electrical and RF ground (counterpoise)

    If you mount your MPET in a wooden or other non-conducting enclosure, just make sure your antenna has a ground to it or counterpoise.

  • So Steve, considering that my Yaesu 86-VR is not grounded to anything in my home, what kind of ground would I need for my MPET project? I do not want it to be 'tethered' to anything, unless of course, nature, science and safety require it.

    Is there some kind of 'internal ground' or 'RF ground' built into handhelds such as Yaesu and Baofeng? Inquiring minds would like to know.

    Thanks...this project is a great idea.

  • edited January 2017

    I never tell people to not worry, but do not worry about this! :smiley:

    Only worry if you plan to erect some mega gigantic antenna array you will hook your MPET all the time, in all weather.

    If you plan to use some small internal ( house) antenna like a 1/4 wave ground plane, J-Pole, mag mount, etc or one of the antennas mentioned but outdoors that you will disconnect during a lightning storm you should be fine.

  • Thanks very much Steve, I understand the point you are making...I only plan to use a 'rubber ducky' type antenna similar to the one on my Yaesu - VX-6R...also planning on a simple 9v battery...
    I purchased the Lexan platform on which I plan to mount all the parts and I'm plotting out the location of all the components...

    The opportunity to post questions and receive help is terrific and I hope some day to 'pay it back' by helping others...for now, I'm still at the starting line...and loving it.

    Take care and thanks again.

  • Steve, your message is coming through on a different page than our last chat about SPST vs SPDT...
    Anyway...I was planning on using the three switches to create 8 binary choices per Chester's idea...
    each switch only needs, i think a '0' or '1' state...
    A little confusing to do this via these web pages...perhaps we can chat on the phone or on the radio or at the next meeting.

  • Here is a pin layout for those implementing a baofeng speaker microphone for the connections to the DB 15 connector pin 4 14 and 12

  • Paul, in the meeting last week I told you to search for a DB-15 Breakout connector.. To refine this a little more, it needs to be a type male and the 2 row type (NOT 3 rows).. Here's a link to an example of one on EBAY. This one is in China, so it will take a Month to arrive.. You might be able to find on in NA, so you can get it sooner..


  • Thanks Pete, this is very helpful...I will research this and let you and others know if I find a quicker source...I really like the idea of the breakout and will definitely use it in the future. Take care, Paul

  • edited February 2017

    MPET Starting Point for the project - Basic MPET project

    What do we need to think about:

    1 - Where do you want to use the Ritron radio?

    2 - Type of project box and where to mount the Ritron board?

    3 - What controls do you want to have? Such as on/off switch, volume control, channel control, power LED, etc.

    4 - What type of antenna do you want? To hook it up to a portable antenna, portable j-pole, or...Where to mount the BNC antenna connector?

    5 - Type of power do you want to have for the radio? Portable or AC connected?

    6 - Do you want to have high and low power setting?

    7 - What type of microphone do you want to use? Speaker mic? Mic only?

    8 - Do you want an external speaker? (Optional if using a speaker mic) How do you control the volume?

    9 - What connector to use for the 15 Pin connecter? How to connected each of these pins as required for the various radio functions?

    What other questions do you need to know to make your project?

  • Chuck, these questions are very helpful in stimulating my thinking about the project.

    When I began I also thought about questions such as:
    A. Why would I want to plop down $30 bucks for this 'thing'?
    B. How would I use it?
    C. Who would I show it to and why?
    D. How will getting involved in this type of project impact my life?
    E. What type of help will I need?
    F. What type of help is available?
    From a technical standpoint in the first week or so I also asked myself.

    a. What other 'stuff' do I need that goes around this Ritron board?
    b. What is the 'real' or 'accurate' name for this 'stuff'?
    c. Where do I get the 'stuff' I need for this project? Who sells it? Who has it?

    Questions are powerful and I appreciate the ones you've listed above...they will be helpful to folks who may begin an MPET or other similar project in the future.

  • We are all here to help, let's use this forum for whatever questions we may have..


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