Loading ...
Sorry, an error occurred while loading the content.
 

CapCo AMA-4 Top band loop

Expand Messages
  • paulyoung004
    Hi all, I have a rare CapCo AMA-4 top band / 80m loop and find even with the control box set to fine tune and set to slowest thats its still too fast. Has
    Message 1 of 4 , Sep 29, 2013
      Hi all,
      I have a rare CapCo AMA-4 top band / 80m loop and find even with the control box
      set to fine tune and set to slowest thats its still too fast. Has anyone got one of these
      loops that they have ether modified the gear box or fitted a new motor ?

      Paul G0HWC
      Photos of my loop Here:
      http://www.g0hwc.com/antennas.html
    • paulyoung004
      I have taken more photos of my top band loop and the inner workings ETC http://www.g0hwc.com/antennas.html I would like to have some way of knowing location of
      Message 2 of 4 , Oct 13, 2013

        I have taken more photos of my top band loop and the inner workings ETC

        http://www.g0hwc.com/antennas.html

        I would like to have some way of knowing location of the tuning of the cap

        and would like advice on this? Maybe some sort or encoder or pot ?

        I have added a close up of the motor gearbox fitting to the cap in the above

        link.


        Many thanks

        Paul G0HWC

        http://www.g0hwc.com




        ---In loopantennas@yahoogroups.com, <paul@...> wrote:

        Hi all,
        I have a rare CapCo AMA-4 top band / 80m loop and find even with the control box
        set to fine tune and set to slowest thats its still too fast. Has anyone got one of these
        loops that they have ether modified the gear box or fitted a new motor ?

        Paul G0HWC
        Photos of my loop Here:
        http://www.g0hwc.com/antennas.html
      • Andy Gardner
        A pot geared into the capacitor drive fed into an ADC would give a good indication of the position of the capacitor. I am building (slowly!) a remote tuned
        Message 3 of 4 , Oct 13, 2013
          A pot geared into the capacitor drive fed into an ADC would give a good indication of the position of the capacitor.

          I am building (slowly!) a remote tuned receive loop. It uses a garden variety superhet variable capacitor and since I only needed 2 of the 3 banks of the capacitor (and the 3rd had less vanes) I removed all but one of the vanes in the 3rd bank and cut the remaining middle vane to use it as an interruptor which triggers opto endstops.

          In the original software version, I would step the capacitor to one endstop, then count the number of pulses needed to get to the other endstop, and then I knew exactly where the capacitor was by keeping track of pulses fed to the stepper.

          In the current version, I don't even bother doing that. When the unit is turned on, where ever the capacitor is at the time is position 0, and I keep track of the pulse from there, giving positions that can be -ve of +ve. The arduino knows what frequency the radio is tuned to, and I manually tune the loop with push buttons, and when peaked I store the capacitor position in memory and the arduino then knows what capacitor position to move to when the tuner is at frequency x. Once I've stored a few positions across the band, the arduino can estimate the correct capacitor position, and as I manually peak each position, the arduino stores more data points and can more accurately esitmate. The arduino has an LED to let me know when it's on a frequency that has been manually peaked. After a few minutes of tuning around the band, the loop is fully tuned, and I can then just move the receiver frequency around and the loop auto-tracks it.

          You have to be careful you feed the pulses to the stepper at a pulse rate the motor likes, or some pulses will be lost and your positioning data goes pear-shaped.

          Once I repair my R8 (it has corroded internal "TMP" rf connectors - and I'm having trouble getting replacements), I'll put a video up.

          Andy
          ZL3APG


          On 14/10/2013, at 6:03 AM, <paul@...> wrote:

          >
          > I have taken more photos of my top band loop and the inner workings ETC
          >
          > http://www.g0hwc.com/antennas.html
          >
          > I would like to have some way of knowing location of the tuning of the cap
          >
          > and would like advice on this? Maybe some sort or encoder or pot ?
          >
          > I have added a close up of the motor gearbox fitting to the cap in the above
          >
          > link.
          >
          >
          >
          > Many thanks
          >
          > Paul G0HWC
          >
          > http://www.g0hwc.com
        • John Sterkeson
          Hi Andy. Try this link for TMP connectors source.... http://therfc.com/taiko.htm These connectors were commonly used in many Motorola base and mobile radios
          Message 4 of 4 , Oct 14, 2013
            Hi Andy.  Try this link for TMP connectors source....   http://therfc.com/taiko.htm
            These connectors were commonly used in many Motorola base and mobile radios at one time.
            The silver plating becomes tarnished and can be removed with a pencil eraser.
            Good luck!
            John...
             
             
            Sent: Sunday, October 13, 2013 7:57 PM
            Subject: Re: [loopantennas] RE: CapCo AMA-4 Top band loop
             
             


            A pot geared into the capacitor drive fed into an ADC would give a good indication of the position of the capacitor.

            I am building (slowly!) a remote tuned receive loop. It uses a garden variety superhet variable capacitor and since I only needed 2 of the 3 banks of the capacitor (and the 3rd had less vanes) I removed all but one of the vanes in the 3rd bank and cut the remaining middle vane to use it as an interruptor which triggers opto endstops.

            In the original software version, I would step the capacitor to one endstop, then count the number of pulses needed to get to the other endstop, and then I knew exactly where the capacitor was by keeping track of pulses fed to the stepper.

            In the current version, I don't even bother doing that. When the unit is turned on, where ever the capacitor is at the time is position 0, and I keep track of the pulse from there, giving positions that can be -ve of +ve. The arduino knows what frequency the radio is tuned to, and I manually tune the loop with push buttons, and when peaked I store the capacitor position in memory and the arduino then knows what capacitor position to move to when the tuner is at frequency x. Once I've stored a few positions across the band, the arduino can estimate the correct capacitor position, and as I manually peak each position, the arduino stores more data points and can more accurately esitmate. The arduino has an LED to let me know when it's on a frequency that has been manually peaked. After a few minutes of tuning around the band, the loop is fully tuned, and I can then just move the receiver frequency around and the loop auto-tracks it.

            You have to be careful you feed the pulses to the stepper at a pulse rate the motor likes, or some pulses will be lost and your positioning data goes pear-shaped.

            Once I repair my R8 (it has corroded internal "TMP" rf connectors - and I'm having trouble getting replacements), I'll put a video up.

            Andy
            ZL3APG

            On 14/10/2013, at 6:03 AM, <paul@...> wrote:

            >
            > I have taken more photos of
            my top band loop and the inner workings ETC
            >
            >
            http://www.g0hwc.com/antennas.html
            >
            > I would like to have some
            way of knowing location of the tuning of the cap
            >
            > and would like
            advice on this? Maybe some sort or encoder or pot ?
            >
            > I have
            added a close up of the motor gearbox fitting to the cap in the above
            >
            > link.
            >
            >
            >
            > Many thanks
            >
            >
            Paul G0HWC
            >
            > http://www.g0hwc.com

          Your message has been successfully submitted and would be delivered to recipients shortly.