Do It Yerself Firestik

Discussion in 'CB Radio Forum' started by The Ed, Jul 15, 2016.

Page 2 of 2
  1. Jul 16, 2016 #11
    Ridgeline

    Ridgeline Road Train Member

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    Ok I guess you need to chart it out and see where the intercept points are.

    L match?

    Which one?

    I would look at calculating the loading coil with low Q and go from there. You don't want a high Q loading coil, do you?

    You can actually use a fixed tuned pi network for a bit more effective circuit, instead of an inductive network as in rabbi's inductive load thing he posted in another thread. Maybe even use a lcc fixed circuit to match everything.

    I think there is a couple articles out there (qst/cq) that takes you through the steps to get it right.
     
    Ridgeline, Jul 16, 2016
    Ridgeline, Jul 16, 2016
    #11
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  3. Jul 18, 2016 #12
    rabbiporkchop

    rabbiporkchop Road Train Member

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    Here is the coil winder I had made to the same diameter as the fiberglass rods I use. (makes it easier to create uniform tension and spacing)[​IMG]
     
    rabbiporkchop, Jul 18, 2016
    rabbiporkchop, Jul 18, 2016
    #12
  4. Aug 8, 2016 #13
    The Ed

    The Ed Bobtail Member

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    Yeah. I've used LCC nets before to match the in and output of a BD139 transistor. I took 150 mW and turned it into 7 watts at 7 MHz. That was nice.

    My point was that an LC network will only have one setting that matches 50 ohms to __+/- j__ ohms. What I was getting at was using such a network to match the antenna, then using the values of components I needed for the match to figure out what the impedance is. I could just build a permanent version of the L match at the base of the antenna and call it good. With anything more complicated than L, I'd have a lot of guessing to do to figure out what my antenna's impedance really is. Figuring out the Z gives me more options on how to match it.

    I would prefer to load a whip or a coiled wire stick with a capacitance hat. I'd see a little higher input Z and would radiate more. The problem is that it's harder to mount those because they add weight to the top. No good. Right now I'm going to work on installing my manufactured antenna and then I'll play with the ones I made. It's possible they could be used as base antennas with a cap hat.

    Ed
     
    The Ed, Aug 8, 2016
    The Ed, Aug 8, 2016
    #13
    rabbiporkchop Thanks this.
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