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  • 50ê - 200ê HF Transformer

    From G8MNY@21:5/101 to WW on Sat Sep 7 23:01:42 2019
    G8MNY TECH 07.09.19 06:15l 53 Lines 1642 Bytes #365 (0) @ WW
    BID : 20571_GB7CIP
    Subj: 50Ω - 200Ω HF Transformer
    Path: OK0NBR F3KT OK0NAG DB0ERF DB0RES DB0EEO DB0GOS ON0AR GB7CIP
    Sent: 190907/0908Z @:GB7CIP.#32.GBR.EURO #:20571 [Caterham Surrey GBR]
    From: G8MNY@GB7CIP.#32.GBR.EURO
    To : TECH@WW

    Here is 4:1 Transformer for HF long wires (New Nov 09)
    (8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
    THIS IS NOT A BULAN!
    An auto-transformer may well make matching a long wire possable on AUTO ATUs that do not have a good impedance range. (e.g. only for SWRs of 3:1)

    It is possable to rewire/switch a bulan to do this.

    At this ratio the ferrite only has to handle 50% of the RF power!
    Turns Ratio 5:10 giving a Z ratio of 1:4

    e.g. 5 turns for 50Ω, 10 turns for 200Ω Balanced.

    ┌──────┐
    │ │6 10
    │ │┌┐┌┐┌┐┌┐┌────o
    │ ├┘└┘└┘└┘└┘ 200Ω
    50Ω Txr │ ▀ │ │▒▒▒▒▒▒▒▒
    Unbalanced └─┬─┘ │▒▒▒▒▒▒▒▒
    │ │┌┐┌┐┌┐┌┐
    │ └┘└┘└┘└┘└┬────o
    │ 5 0 │ _│_
    └───────────────┘ ///

    Make sure they are phase & connected correctly.


    In general a transformer turns ratio is square root of the Z/Z.
    So for 600Ω to 50Ω that is √600/50 = √12 = 3.46 or 2:7 3:11 4:14 5:17 turns etc.

    An autotransformer tapped system where the lower turn is a tapping of the total also the lower turns should be 2x thicker!
    ┌──────┐
    │ │6 17
    │ │┌┐┌┐┌┐┌┐┌┐┌┐┌────o
    │ ├┘└┘└┘└┘└┘└┘└┘ 600Ω
    50Ω Txr │ ▀ │ │▒▒▒▒▒▒▒▒▒▒▒▒▒
    Unbalanced └─┬─┘ │▒▒▒▒▒▒▒▒▒▒▒▒▒
    │ │┌┐┌┐┌┐┌┐
    │ └┘└┘└┘└┘└┬────────o
    │ 5 0 │ _│_
    └───────────────┘ ///



    Why Don't U send an interesting bul?

    --- Mystic BBS v1.12 A43 (Linux/32)
    * Origin: HAMRADIO telnet slacko.kozow.com (21:5/101)