Modifications for the Yaesu FT-70

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
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

This counter shows the number of hits since the 9th February 2000

Go Back To The Yaesu Mods Page

Go Back To The Main Modifications Page

Go Back To The CB / HAM Radio Main Page

Go Back To The Main Home Page

Copyright © The Defpom 1997-2008