ICOM IC-7100 low SSB power modification - IMPORTANT ADDENDUM

Hi guys

Further examination of schematic diagram and ALC ciruit lead me to find few points and questions I couldn't answer myself, so decided to ask Marios SV0CL about.


Here is answer Marios SV0CL send me today :

"" This modification is an easy way to add few miliseconds delay to the ALC action (ALC TIME CONSTANT).

In practice as soon as you start talking to the microphone, power output starts increasing and the ALC has to act and
control this power to the preset level (i.e. 100W PEP)

The IC-7100 has a very "fast" ALC, it acts earlier and voice has no chance to produce much power.

By delaying the ALC action ssb voice has more time to do the job. ""


IMPORTANT INFORMATION
Marios, asked me also to clearly STATE that WE SHOULD NOT make BOTH modifications together.


This was not clearly stated before, and short modification description did not say anything about.
Althought my radio has both mods and working fine, this could lead to some unexpected behaviour.

I will post any effect of further investigation later.


73!

ICOM IC-7100 low SSB power modification

Hi guys.

I hope this will end problems with IC-7100 low SSB power. Because ICOM did not recognizes the problem, and we know there's a problem as always solution is bring by HAM RADIO community.

This is not my mod, and this is not official ICOM mod in any way.

WARNING ! ! !

NO ANY PERSON MENTIONED BELOW SHOULD BE TREATED GUILTY IF YOU DO SOMETHING WRONG AND DAMAGE YOUR RADIO.
THIS IS INTERNAL HARDWARE MODIFICATION, SO ALL WHAT YOU DO, IS YOUR OWN RESPONSIBILTY.

My sincere regards to my Greek friend Manos SV7GBR for support, and OM Jorge PY3CC for sharing the mod with us.

and finally BIG KUDOS for Mr.Marios SV0CL for great job with the mod.

Let's go: Remove all screws to get to the bottom of main unit and locate part of our interest:

According to SV0CL there are two steps we can perform to get more SSB power:

FIRST mod - "SOFT" - simple jumper added at point labelled "1" on picture below. You can use 0 Ohm SMD resistor as well soldered right to the ground plane. This should double total SSB power.

Schematic diagram MAIN UNIT, lower right corner, page 10-5 in Service Manual.

PCB look - Main Unit, bottom side, Service Manual, page 7-4.

Closer look - mod " 1 " point.

You can solder jumper in this place, or do it my way - 0Ohm SMD 0805 resistor.
Scratch small point of ground just behind the parallel capacitors:

Gently solder the resistor both sides - one to ground, another to capacitors :

This is end of mod "1 "

===================================================================

SECOND mod - "HARD" - should give full power on SSB, labelled " 2 " - 10uFd capacitor added across R1522 slightly below mod " 1 " with positive "+" leg attached to R1523. According to Jorge PY3CC this capacitor is Tantalum one, but looking at schematic diagram, any good quality 10uFd will do the job.

Closer look - mod " 2 " point

Prepare 10uFd capacitor, standard or tantalum. According to legs You can do it your own way. This is how I did it :

Positive leg is soldered between R1522 and R1523, negative is soldered to R1519 ground side.

Another look :

Secure the capacitor with small amount of nail enamel ( ask your XYL ) or any other silcone glue to prevent mechanical stresses when in mobile.

This is end of mod " 2 ". Assembly the 7100 cover and enjoy.
Perfomed with my own radio S/N 03001722.

Again big thanks to SV0CL, SV7GBR, and PY3CC for sharing the "know how"

73 !