Saturday, April 22, 2017

Trimming the dipole

I took 20 inches off each end of my dipole (12 inches then 8 inches), and based on my measurements I think I got it to resonance around 6.9Mhz.  Ballparking, I think the SWR there is 1.6, going up to about 1.8 at 7.2mhz.  I was going to tinker with it more, but don't really have time today.

Also, got a new SLA battery (12v, 12 Ah), which means I'm not running through AA like mad.  However, the IRF510 in my amp is running really hot.  Maybe it is because I'm pumping in square waves rather than the sinusoidal I think this was originally designed for, maybe I just have other biases off.  Never did get the 5 watts I expected, so very likely I wired something wrong in this.

In any case, it has started thinking about maybe looking into class E amplifiers here (since I'm starting with a square wave anyway). 
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5 comments:

  1. StretchymanJune 1, 2020 at 10:23 PM

    Square wave in is what you want for class E, you just have to get the O/P 'tuned' correctly.

    ReplyDelete
    Replies
    1. Ben SandersJune 2, 2020 at 3:31 PM

      Thanks! Do you have a good resource for tuning them? I think I understand the theory, but don't really understand how to tune them without being able to view the current waveform.

      Delete
  2. StretchymanJune 3, 2020 at 7:20 AM

    Get a scope, simple as, no excuse. You dont any electronic work without one and they're cheap from CH.

    ReplyDelete
    Replies
    1. Ben SandersJune 3, 2020 at 9:07 AM

      I have a scope, and I view the drain voltage, but how do you view the drain current?

      Delete
  3. StretchymanJune 8, 2020 at 4:03 AM

    Yes view the Voltage!

    ReplyDelete

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