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TUCoPS :: Radio :: ft70g.txt

Yaesu FT-70G mods




FT70G

    The Yaesu FT-70G is a very rugged HF-SSB QRP tranceiver with a self-
    contained Ni-Cd battery. This modification restores operation on 160
    meters and improves receiver sensitivity between 50 KHz and 2MHz.
    (It enables transmit operation between 1 and 2 MHz, but 2nd harmonic
    attenuation will be very poor if used below 1.5 MHz.) The boards
    are stenciled for the added parts, but this is no "clip the diode"
    modification:

    Low Pass Filter (LPF) Unit:

    Add RL601 SPDT relay, 12Vdc (Yaesu p/n M1190066) I substituted a
               Radio Shack 275-241 with little trouble. See note.
     "  RL-602 (same as above)
     "  C601   0.022uF,50V,ceramic
     "  C602   560pF,50V,ceramic
     "  C603   390pF,50V,ceramic
     "  C604   620pF,50V,ceramic
     "  C605   2200pF,50V,mylar
     "  C606   220pF,50V,ceramic
     "  C607   560pF,50V,ceramic
     "  C608   680pF,50V,ceramic
     "  C609   0.01uF,50V,ceramic
     "  L601   29T of #26 enameled on Amidon T37-2 iron powder torroid
     "  L602   26T of #26 enameled on Amidon T37-2 iron powder torroid

     Note: The R/S relay has 2 pins connected to the wiper arm. Connect
           only one to the non-grounded circuit board trace. The 2nd pin
           on the Yaesu relay is a dummy pin and is soldered to the
           board's ground plane for mechanical stability only.

    RF/IF Unit:

    Remove R26  470 Ohm,.25 W
      "   R25  4.7 KOhm,.25W
    Replace R25 with a 470pF ceramic capacitor

    Reg/Cntrl Unit:

    Remove jumper C-A
    Add    jumper B-C
     "   D601   1N914
     "   C601   0.022uF,50V,ceramic
     "   Q601   2SC1959Y (SK9229/ECG85)
     "   R601   18 KOhm,.25W
     "   R602   39 KOhm,.25W
 


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