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  • He Who Shall Not Be Named
    Moderator
    • Aug 2008
    • 12254

    OK. turns out the ESC was bad. Replaced with a new one and the motor works fine. I now have a severe range problem. I took Andy's advice and got the BEC away from the receiver, but still I get glitching at only 50' with extended transmitter antenna. Pitiful!

    But, Andy put the thought in my head, and I extended the idea of a signal generator in close proximity to the receiver swamping the front-end with too much RF 'noise'. Right now I have Kevin's AD2 angle keeper servo taped to the side of the receiver. Tomorrow I re-locate that away and see if I get a good range.

    The battle continues.

    David
    Who is John Galt?

    Comment

    • Subculture
      Admiral
      • Feb 2009
      • 2119

      A leveller shouldn't be giving off any RFI.

      The electrically dirty things in a sub are brushed motors, ESC's and switchmode BEC's. You may want to try earthing out the aluminium tech rack.

      Comment

      • He Who Shall Not Be Named
        Moderator
        • Aug 2008
        • 12254

        Originally posted by Subculture
        A leveller shouldn't be giving off any RFI.

        The electrically dirty things in a sub are brushed motors, ESC's and switchmode BEC's. You may want to try earthing out the aluminum tech rack.
        Good points, Andy. I'll ground the tray to the receiver ground and see how that works.

        Check me on this: I'll run a lead from an unused port of the receiver and attach the black (negative/ground) wire to the tray. Or will you read about some stupid American killing himself in a shop accident?
        Who is John Galt?

        Comment

        • Subculture
          Admiral
          • Feb 2009
          • 2119

          That'll probably work, but best practice is to run it to the battery terminal, to avoid grounds at different potentials. Don't think it'll make much difference in this instance though. other things to try, if the receiver is crystal based, try substituting an alternative crystal, also try the same in the TX. Also worth trying a linear BEC in place of the switchmode in case that is the culprit. I use the same model of BEC without issue, but maybe the 75mhz is a bit more sensitive than our 40mhz.

          Comment

          • He Who Shall Not Be Named
            Moderator
            • Aug 2008
            • 12254

            Thank you for the quick response and pointer. Battery ground it is, sir. I'll keep you informed. Before that I'll isolate the BEC and range check with a dedicated receiver battery.

            David
            Who is John Galt?

            Comment

            • MFR1964
              Detail Nut of the First Order
              • Sep 2010
              • 1290

              David,

              Take some copper mesh, make a small box, in which you can place the BEC, this will act as a cage of farady, keeping the RF signals inside.
              Maybe also some a ferrit core around the leads coming in and out.

              Manfred.
              Last edited by MFR1964; 10-10-2020, 07:12 AM.
              I went underground

              Comment

              • He Who Shall Not Be Named
                Moderator
                • Aug 2008
                • 12254

                Good stuff, Manfred. I'll employ these ideas if the others don't pan out. Thanks.

                David
                electronics moron
                Who is John Galt?

                Comment

                • He Who Shall Not Be Named
                  Moderator
                  • Aug 2008
                  • 12254

                  OK, this request goes out to you common air-breathers who bask in the glory of my earth-shaking presence, a request of assistance:

                  May I ask you kind sirs, does anyone have any Futaba, 75Mhz FM Dual Conversion Crystals for sale? Specifically I need a TX and RX pair; and if at all possible, I would like two of the RX crystals.

                  And I want them now!

                  Thanks.

                  David
                  The All Powerful
                  Who is John Galt?

                  Comment

                  • Subculture
                    Admiral
                    • Feb 2009
                    • 2119

                    No such thing as a dual conversion TX crystal. The dual conversion only applies to the RX, and that is the only part that requires a special crystal. Can't help you with the receiver crystals though, the 75mhz band is largely exclusive to USA.

                    I take it you've thrown in the towel with the Novak RX, as it looks like a synthesized model.
                    Last edited by Subculture; 10-13-2020, 11:01 AM.

                    Comment

                    • He Who Shall Not Be Named
                      Moderator
                      • Aug 2008
                      • 12254

                      Originally posted by Subculture
                      No such thing as a dual conversion TX crystal. The dual conversion only applies to the RX, and that is the only part that requires a special crystal. Can't help you with the receiver crystals though, the 75mhz band is largely exclusive to USA.

                      I take it you've thrown in the towel with the Novak RX, as it looks like a synthesized model.
                      Yeah, I knew that. I pretty much cut-and-pasted what the SKIPJACK customer was looking for.

                      Like Bob's current battle with his big Type-21, this RTR job has taken a long time with many 'interesting' problems to solve.

                      And you're right, the Novak just would not talk to the transmitters the client submitted to me. However, by going with one of my VEX transmitters and the synthesized Corona (love those things!), I did come up with a workable r/c system for the job. Likely I was trying to get the Novak to work a band it was not tuned for.

                      Crystals are becoming an ever increasing source of angst in this game.

                      I imagine in a few years I'll retreat back to static scale model building -- my roots and my first love. R/c aircraft, boats and cars interest me not in the slightest.

                      David
                      Who is John Galt?

                      Comment

                      • Rick Teskey
                        Lieutenant Commander
                        • Jan 2009
                        • 233

                        We will just become 72 mhz outlaws! We need new sombra labs recievers !

                        Comment

                        • He Who Shall Not Be Named
                          Moderator
                          • Aug 2008
                          • 12254

                          Originally posted by Rick Teskey
                          We will just become 72 mhz outlaws! We need new sombra labs recievers !
                          Sadly you are right on point, my snow covered creature friend. Thank god I held onto the airplane gear -- it might come to that some day.

                          David
                          Who is John Galt?

                          Comment

                          • Subculture
                            Admiral
                            • Feb 2009
                            • 2119

                            Fantastic radio equipment available these days, and much of it uses modular tuners e.g. the Frsky and Jumper ranges are excellent examples, and they can be had for much less than the cost of a basic 2-channel rig back in the day.

                            The snag is that the older lower frequencies are no longer of interest to major manufacturers as there is little market for them beyond lunatics like us.

                            Here's the thing, it's just a basic tuner and receiver that is required, all the clever stuff is done inside the transmitter. The designs for tuners are mature and by and large open source, so they could be reproduced.

                            Course to make that viable, we need a few buyers. So it needs a bit of organisation.

                            In another vein, there is still a lot of good secondhand and NOS radio equipment washing about to largely satisfy demand. I haven't soon too many people complaining about difficulties entering the hobby through lack of available radio equipment.

                            I still maintain the biggest existential threat to the R/C sub hobby is the ageing demographic, and I'm far from convinced organisations and groups representing the hobby have the will or concepts to address this.

                            Comment

                            • He Who Shall Not Be Named
                              Moderator
                              • Aug 2008
                              • 12254

                              Originally posted by Subculture
                              Fantastic radio equipment available these days, and much of it uses modular tuners e.g. the Frsky and Jumper ranges are excellent examples, and they can be had for much less than the cost of a basic 2-channel rig back in the day.

                              The snag is that the older lower frequencies are no longer of interest to major manufacturers as there is little market for them beyond lunatics like us.

                              Here's the thing, it's just a basic tuner and receiver that is required, all the clever stuff is done inside the transmitter. The designs for tuners are mature and by and large open source, so they could be reproduced.

                              Course to make that viable, we need a few buyers. So it needs a bit of organisation.

                              In another vein, there is still a lot of good secondhand and NOS radio equipment washing about to largely satisfy demand. I haven't soon too many people complaining about difficulties entering the hobby through lack of available radio equipment.

                              I still maintain the biggest existential threat to the R/C sub hobby is the ageing demographic, and I'm far from convinced organisations and groups representing the hobby have the will or concepts to address this.
                              As usual, Andy, you put the point on it. Bottom line: this 'hobby' dies with us.

                              Twenty-years from now all this gear will be at the mid-level of the local active land-fill.

                              David
                              Who is John Galt?

                              Comment

                              • Subculture
                                Admiral
                                • Feb 2009
                                • 2119

                                I don't think it'll die out completely, I just don't think it'll be the same, and I think the hobby will probably be a lot smaller and/or participation will be very different.

                                There are lots of factors that influence this, some of which are easier to mitigate than others.

                                Comment

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