Hardware Hacking

Receive and Transmit Expansion for ICOM IC-707

1. Remove power and antenna
2. Remove screws and open case
3. Locate front unit board (The one behind the dial)
4. In Version 1: Locate and remove Diode D12

[] D12 [] D13
[] D11

Conversion to lower sideband.

Remove power, antenna, and microphone.
Remove upper and lower covers.
Remove PLL board.
Locate L12. Beside L12 is a 12 pf capacitor, replace this with a 47 pf.
Adjust L12 for best clarification on known signal source.
Reassemble radio.
You now have lower sideband and cw.

Remove bottom cover. With the radio upside down and display facing you remove
the synthesizer board with the four screws, this is near the front of the radio.

This gives access to the small board underneath with the surface mount
components on it. Locate the processor chip IC401 (UC-1208).Locate pins 28 and
29 which are on the right hand side of the chip and are 4th and 5th from the
top. Note they are bridged with solder.

CAREFULLY cut the copper track NEXT to the pins. DO NOT attempt to unsolder the
two pins form the board. Use a GROUNDED soldering iron. Locate the two rows
of connector pins above the chip.

On the bottom row locate the last pin on the right. Verify with a VOM that this
pin has + five volts. Solder a 10k (1/4 w) resistor between this pin and pins
28 and 29 on IC401.The synthesizer will now tune from 26.00 Mhz to 30 Mhz.

——————————————————————————-

*Simple RF Wattage Enhancement to 35 Watts

With the radio in the same position as before, locate VR5 in the top
left hand corner. This is the RF high power preset.

Lift and bend the wiper so that is is permanently disconnected form the track.
Solder a 47k resistor (1/4 watt) between the wiper and the left hand side of
the track.

This should increase the RF power output to around 35 watts but you will now
not be able to trim the power output. The Low power trim will function as
before.
——————-

Enhancement of Microphone Frequency Response

1) To increase average depth of modulation
– — ————– —– — ———-
Remove top cover of the radio and with the display facing you and the radio
upright locate IC3 (MJM45585) near the bottom right hand corner of the main
large board.

Just to the right of this IC locate c75 (56 pf) and remove it. This will
increase the gain of the microphone Preamp considerably but without
overmodulation. If you find the compression excessive(i.e. background noise)
open the microphone and insert a 470 ohm resistor between the hot side of the
mic insert and the input (white lead).

This will reduce the gain somewhat but will still give you much increased
“talk power” (percy’s words, not mine. Adam).

2) To increase audio response in the high mids
– — ——– —– ——– — — —- —-

This simple mod will recrease the audio response in TX in the 2 to 2.7 khz
region giving higher articulation and move intelligibility under weak signal
conditions.

Locate IC3 as before on the large main board and the radio positioned as before.

Locate a 5.6k and a 4.7k resistor just below IC3.
Solder a 0.015 mf (16v) capacitor between the left side of the 4.7k to the
right side of the 5.6k resistor.

These two mods work together to give improved readability on SSB under DX
conditions.

Remove the top cover and locate the main PC board (it’s to the rear or
the
chassis and holds the speech option, see the operators manual). R516,
R517
and R518 is located in the right hand corner inside the small metal
can.
There will be 4 adjacent resistor positions with 2 positions populated
(R517 & R518)the top position is unknown. The small metal can is
located
on the right hand side of the main board. R455 is located below and to
the
left of J12 (the speech module connector). R455 is also unpopulated and
it’s to the left of R140.

If you can’t find a 603 size surface mounted resistor, carefully
unsolder
an exsisting resistor and re-populate it in another position. R455 can
be
replaced with a zero Ohm resistor by shorting the position with a fine
stran of wire that was taken from a ribbon cable.

After the modification, the radio will lose it’s memories and will
require
reprogramming.

Icom 207H Dual Band Mobil…..

remove the 4 screws ataching the bottom cover and remove the cover. (I had to
use a small screwdriver to pry on the cover. It’s made to fit tight)
with face toward you and belly up look to far right of board and close to you
locate a row of SMT diodes 3 on top then a shift to right and a few more.
The three are in a PERFECT row top to bottom! count from the top of the row
1 2 3. Remove the # 2 & 3 diodes. Now continue looking down from there and
you will see a resistor sticking up in the air (W14). Clip the lead off of
the resistor. Reassemble the radio and preform a CPU reset by holding the
Set and S.MW buttons while turning the radio on…(page 69 of manual).

You now will have :

118-135 RX (stock)
136-174 TX & RX
320-399 RX
400-479 TX & RX
849-950 RX

The Transmitter will work and transmit at ALL of the listed

This mod is easy to preform and takes about 10 minutes to accomplish.