Building a RF DEmodulator

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • solomon_grundy
    New Member
    • Sep 2012
    • 4
    • Puerto Rico

    #1

    Building a RF DEmodulator

    I have a Cisco DTA50 (with coax input & output) that would like to send to the RCA - maybe even component - input of my LED TV so I can leave coax (RF) input for QAM signal. I've been looking everywhere for a cheap answer - short of using a busted VCR - but all I've found are industrial grade equipment - $250.00 up - or other that include a TV tuner.
    Anyway, I'm just trying find an schematic that will let me build one myself. I think it should be "easier" than most I've found because I don't need to implement a tuner since I'll be using the DTA to switch channels. Any help will be appreciated.
  • bluto
    Badcaps Veteran
    • Oct 2007
    • 557

    #2
    Re: Building a RF DEmodulator

    You are not going to be able to throw one together in any reasonable amount of time. You could either take broken VCR, remove the mechanical bits and then transplant it into a smaller enclosure or just purchase one of the below purpose build demodulators on ebay. To do otherwise is not realistic.

    http://www.ebay.com/itm/NTSC-Coax-A-...item48424cd283

    http://www.ebay.com/itm/Super-Video-...item1c08d9a0b2

    Comment

    • solomon_grundy
      New Member
      • Sep 2012
      • 4
      • Puerto Rico

      #3
      Re: Building a RF DEmodulator

      Originally posted by bluto
      You are not going to be able to throw one together in any reasonable amount of time. You could either take broken VCR, remove the mechanical bits and then transplant it into a smaller enclosure or just purchase one of the below purpose build demodulators on ebay. To do otherwise is not realistic.
      Thanks for the prompt answer. I think I'll end up doing just that; break apart a VCR (hopefully with s-video) and mount a slimmer version. At least I got a straight answer.

      Comment

      • budm
        Badcaps Legend
        • Feb 2010
        • 40746
        • USA

        #4
        Re: Building a RF DEmodulator

        You may look at this one:
        http://www.alltronics.com/cgi-bin/ca...gi?item=23v004
        Never stop learning
        Basic LCD TV and Monitor troubleshooting guides.
        http://www.badcaps.net/forum/showthr...956#post305956

        Voltage Regulator (LDO) testing:
        http://www.badcaps.net/forum/showthr...999#post300999

        Inverter testing using old CFL:
        http://www.badcaps.net/forum/showthr...er+testing+cfl

        Tear down pictures : Hit the ">" Show Albums and stories" on the left side
        http://s807.photobucket.com/user/budm/library/

        TV Factory reset codes listing:
        http://www.badcaps.net/forum/showthread.php?t=24809

        Comment

        • ben7
          Capaholic
          • Jan 2011
          • 4059
          • USA

          #5
          Re: Building a RF DEmodulator

          RF circuits are very tricky, as suggested, you should hack something else instead of building from scratch.
          Muh-soggy-knee

          Comment

          • solomon_grundy
            New Member
            • Sep 2012
            • 4
            • Puerto Rico

            #6
            Re: Building a RF DEmodulator

            Originally posted by ben7
            RF circuits are very tricky, as suggested, you should hack something else instead of building from scratch.
            I've seen schematics for RF tuners and yes, they are tricky. But since I already had a tuner I thought I just needed something that would separate the signal to video and audio L/R. Anyway, I'll go VCR way and I'll see if I can do without the tuner.

            Comment

            • ben7
              Capaholic
              • Jan 2011
              • 4059
              • USA

              #7
              Re: Building a RF DEmodulator

              Originally posted by solomon_grundy
              I've seen schematics for RF tuners and yes, they are tricky. But since I already had a tuner I thought I just needed something that would separate the signal to video and audio L/R. Anyway, I'll go VCR way and I'll see if I can do without the tuner.
              Sounds good!

              P.S. I am actually working on a crystal radio right now, but it doesn't work, yet :/
              Muh-soggy-knee

              Comment

              Related Topics

              Collapse

              • DXseekerMO
                Samsung PN51F8500AFXZA broke off the tuner's F connector, can't get tuner de-soldered
                by DXseekerMO
                I can hear Fred Sanford now...."YOU BIG DUMMY".....I pulled the "F" connector out of the tuner by accident. The tuner number is BN40-00248B. Low and behold I had a scrap board with tuner number BN40-00248A. Although the tuner is different (according to Encompass.com) it's footprint on the board is exactly the same as the 248B so I decided to de-solder the tuner off the scrap board to see what I was getting in to.

                As you can see in the picture the terminals and solder pads are super small. No matter what I tried I could not get either the terminals or support...
                09-15-2021, 05:15 PM
              • Mark R
                Does Changing Out Caps In A Tuner Effect FM Reception
                by Mark R
                "TQ" Subject at hand is a Marantz 120 tuner. The tuner lit up but no output. Recapped the entire unit. Before it was working fine tuning in Stereo and Mono. Now it just about tunes Stereo and some of the mono stations are weak. Nothing else was changed. When you do hit a stereo station the stereo lamp will come on but flickers as it's trying to hold the MPX signal.

                I don't see how bringing the unit back with new caps checked by my Sencore LC103 would effect the FM section. Every Value is as it was from the factory?

                Any Thoughts?
                06-11-2024, 07:04 PM
              • Jacksoft
                Samsung 225MW EEPROM bootloop
                by Jacksoft
                Hi all,
                I got an old Samsung 225MW TV with BN41-00825 motherboard.
                Since the TV has a buzzer when it starts it makes a beep. The main problem is that the TV goes in a sort of bootloop and beeps every 2-3 seconds.
                So I attached the VGA UART cable and read the debug data using a RT809H programmer:


                According to the Service Manual all the voltages looks good, so I made a backup of the internal flash and all the EEPROMs (1 Settings + 3 EDID) and cleaned the EEPROM.
                Now the TV boots but it's stuck on VGA. If I try to change the source it goes to TV, restarts...
                02-14-2025, 04:18 PM
              • Ierwin
                55PFL4908K/12 DVB-S tuner not available
                by Ierwin
                Hello everyone,

                I have a rather strange problem with this Philips I just repaired.
                The set came with startup problems, I checked the PSU, found some puffed caps, replaced them and now it is starting perfectly.

                According to the philips website this tv should be equipped with a tripple tuner.
                However there is no option to scan for satellite channels in the menu.
                It only shows the option to search for DVB-T or DVB-C channels.
                The set is equiped with the F-type connector in the back so to me it looks like it is indeed equipped with a Sat tuner....
                11-10-2023, 12:05 PM
              • Mark R
                Marantz Model 120 Tuner Craziness I am Stumped!
                by Mark R
                My Marantz 120 Tuner stopped receiving Stereo signals. It works fine other then Stereo. I have a fully loaded shop here with all test equipment except and RF signal Generator.

                I get great reception on FM so I have used that signal troubleshoot. I have been all over the MPX board and replaced all caps. Also the entire power supply caps were replaced.

                All Voltages on the MPX board are good... all Transistors Good...All Diodes Good and other components.

                The stereo lamp is good as I powered it up and it lights. The signal flow to that lamp is unbelievably...
                10-20-2023, 01:25 PM
              • Loading...
              • No more items.
              Working...