I recently bought a second hand Icom IC-7100 HF radio for a reasonable price. This radio is known for a very conservative approach to internal ALC on the power output. This causes the output power to not go above approx 75-80W (PEP) as measured on my LPA-100 wattmeter in PEP mode with 14,5V DC input. Of course, there is no need to overdrive any linear amplifier, however Icom engineers have probably overdone it a bit on the conservative side on this radio (?).
There are two published mods that are possible on this radio. I did only one of the mods that involves a jumper from C1509 to ground, because the other mod that involves a 10uF capacitor is reported to cause modulation issues on FM and AM.
The PEP output power increased from 75-80W PEP to approx 140-145W PEP (14,5V DC input). Note: PEP, not average. On a sidenote the peak to average ratio also improved. There is no need to have PEP output of more than 100-110W PEP by the way.
The mod is easy:
- Unplug the radio DC lead and all other leads incl. the antenna connector
- Use an antistatic mat and handlead
- Remove the back cover
- Locate the C1509 and the ground lug
- Solder a small jumper from the C1509 to the ground lug
- Check carefully that you didn’t spill any solder residue on the PCB
- Blow with compressed air to remove any residue
- Close the radio
IC-7100 mod. (I did steal this picture from radio aficion website)
I did also upgrade the firmware to :
- CPU 1.11
- DSP 1.03
The firmware upgrade did have a small but insignificant effect on the PEP output power according to what I found. The hardware mod, did have a signficant impact as the DSP is led to believe that the output power is lower than it is.
Disclaimer:
- All mods are done on your own risk!
- You may void the warranty of your radio if carrying out this mod
- I will not be held responsible for any problems, malfunctions, defects, indirect consequences or any other issues caused by the mod
- Do at all times follow the license regulations of your country
- Check that your bandwidth is not excessive
- Check that your harmonic content is well below maximum allowed
hi, i have an Icom 7100 with same issue / where did you get this mod from / it won’t affect its performance on any other mode? Why so many videos with both mods Jumper and Capacitor?
Thanks / 73 / wp4jk
Hi, this mod is originally from Icom Greece (I believe). You can choose to do either the only cap mod or both mods. Its up to you. I choose to do only the cap mod on this radio. I believe AM modulation and perhaps also FM modulation level may be affected by this. At least the TX modulation level on my radio is a bit low on AM and FM modes. On SSB the mods help quite a bit.
Hey guys,
my experience is strange and different to one here:
first I have added the 10uF. –> so far I thought problem solved, but last sked, I could all but no one me. So I checked again.
Have added the bridge to ground.
Strange: small improvement in SSB, but in FM less and modulated carrierer with about 10Hz. UPs. did I make a mistake.
So bridge removed. and checked the wiring of Elko again.
What is this? parallel to the Elko to R1522 with 2,2KOhm, I measured about 10Kohm. How can this be.
Printing error, but in BOM also 2,2Kohm listed.
So finally and also hint from my friend Helmut, who did modification many years ago. He recommended only the bridge.
So I removed the Elko, but instead a Resistor with 2,7kOhm parallel to the current measured value of 10khm.
What can I say –> Fully success in all modes.
I absolute have no idea, why this resistor is wrong or broken or already someone did changes. I bought it second hand.
anyhow, check this resistor. Feedback would be great.
vy 73, Tom
Interesting! Thanks for sharing!