Modifications for the Yaesu FT-70

Modifications for the Yaesu FT-70

19-07-1998 FT-70G work in 50 KHz to 2 MHz

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