[Icom_IC-7100] Low power output on ssb

A number of users have commented that the average power output of the IC-7100 on SSB, as measured on a moving coil power meter appears low compared with other transceivers. Having made some bench measurements it would appear that this is not so much a fault but rather a result of the very effective ALC on the radio that prevents it being overdriven. A correctly driven SSB transmitter should show the following approx power measurements :
                         Measured on moving coil meter              Measured on PEP reading meter                   Measured on Oscilloscope

Single Tone input                                   100W                        100W                              100W (peak)
Two tone input                                        40W                         100W                              100W (peak)
Speech input                                       12-20W                        100W                              100W (peak)

The reason for the lower reading on the moving coil meter is due to a number of factors including the inherent inability of this type of meter to follow a rapidly changing speech waveform.

Only a true PEP meter or oscilloscope will give a true indication of PEP, cheap wattmeters with a supposed PEP indication often have no more than a capacitor switched across the meter which again will not give a correct power indication.



Most SSB transceivers incorporate an ALC meter to allow the user to adjust gain levels to suit their operating conditions. It is very common for operators to drive a transmitter hard into ALC which will increase the apparent output power indicated on a moving coil wattmeter by increasing the average value of the waveform. This often results in the transmitted waveform flat topping on peaks and can introduce distortion and 'splatter' on the transmission. The ALC on the IC-7100 will not allow it to be driven past the point where distortion is introduced resulting in a much cleaner signal but expect a slightly low reading than from models that it is possible to overdrive.


8 comments:

  1. Icom IC-7100 it is realy great TRX but it has one big problem!
    It not depends on type of mic, mic gain, compression, ACC or USB input.
    CW, FM, or single tone SSB gives full power 50W (VHF), human voice SSB or digi mode SSB with few tones same time gives 37W (VHF). I want same power on SSB as on CW - with same % in radio setup...
    This problem is easy way to burn your SSPA.

    It is ICOM mistake. We check it on many professional power metters.
    Please stop talking foolishly things about that... just find solution and publish it !


    regards
    Andy SP3IYM

    ReplyDelete
  2. Anonymous9/14/2015

    Last year I ran an SSB "talk power" test on an IC-7100 in my lab, and was able to confirm that the IC-7100 lacks "talk power" on SSB in comparison with other Icom radios. This is especially noticeable with compression activated.

    I wrote up a report, and submitted it to Icom Japan during APDXC 2014 in Osaka last November. I was given an assurance that the engineers would analyse my report and look into the matter. I have done about as much as I can. It should be possible to correct this in a new firmware release.

    Of course there is a fine line between adequate "talk power" and excessive IMD. This will have to be considered in the course of any firmware rewrite.

    ReplyDelete
  3. Anonymous9/14/2015

    all IC-7100 have this problem.
    Its not possible to solve it with other Microfon.
    The problem occurs by passing the DSP.
    The slewrate of the signal in combination with a fast Gain control by TX
    ( what a amazing combination!!!) will impact the problem.
    Therfore the "voice" level only occurs a to low ssb output if you
    wishstle ( this is much longer than a vocal in normal speech) you will
    reach the 100 W, but not in normal speech behavior.


    I was on Hamradio 2015 in Friedrichshafen last week on the big Icom
    area, the know the problem (Icom Germany in Bad Soden) and they are in
    contact to Japan and they hope for a Software Update for DSP in the next
    time.


    So save your time to "work" in the Audio Menue its useless.
    Better activate MOD Level in SSB to 35%, compression to 10,
    Tonecontroll, SSB,TX,TXtreble to +2 and use TBW Wide ore TBW Mid for
    best results.


    The latest Software E4 had not solved the problem.

    ReplyDelete
  4. Anonymous9/14/2015

    I read the thread with interest. I have just checked my IC7100 using a scope and dummy load and I do indeed get 100 W PEP on normal speech peeks but never over however hard I try, due to the very fast TX gain control. The Power Out (Po) reading occasionally hits 100% on these 100 watt speech peaks when the ALC reading just peaks at the right hand end of the ALC scale. This means I am still keeping the ALC reading in the required region as mentioned on page 3-24 of the basic manual.

    Mic gain is 55%, compression level 5, TBW Medium (200Hz - 2.9kHz), Tx Bass -4, Tx Treb +1

    (Note that I am using a lightweight headset. If I use the HM-151 mic then Tx Bass and Treble are adjusted accordingly but power output is still 100W peak on HF/6m)

    I have not had reports of low signal strength when compared to my other transceivers or reports of poor signal quality. I don't appear to see a low power problem on SSB but others have.

    ReplyDelete
  5. Anonymous9/14/2015

    My observation and solution-----
    When I first got my 7100 back in October of '13 I immediately noticed the low SSB output. Tried all my different mics and then pulled out an old Icom IC SM-6 amplified desk mic that I bought at least 30 years ago.
    I made up an adapter cable round male 8 pin to the 8 pin modular. I can easily get 90 to 100 watts output on my LP100A Digital Vector RF Wattmeter on all HF bands. Though not scientific I monitor my signal on other radios in the shack and looked at it
    on the Elecraft P3 screen and on my Flex 5000 and it looks very clean. I have not had any reports of bad audio from on the air contacts.
    I am sure others will disagree but sometimes simple solutions can dispel a lot of anxiety.
    Mike WA8EBM

    ReplyDelete
  6. Anonymous9/14/2015

    Finally got the 7100 back after repair (new PA board, new main board and new head unit) and can now show 80w on 15m (not peak reading and using 50% mike gain, no compression) and 90 watts on 90% power on RTTY (for a very short time).

    Seems it had multiple problems from new but all is good now.

    73 Phil M0TZZ

    ReplyDelete
  7. Anonymous11/23/2015

    I have experienced similar problems with my 7100. Output power shows 100% on the 7100 while external meter shows 20 watts talking or whistle (no matter what mic gain, etc settings I tweak).
    Interesting that this all started when I first hooked up USB and ran digital.
    CW is still 100 watts out.
    USB-D is also 0-100 watts out depending on the USB MOD Level.
    I reset the xcvr and even that didn't fix the problem.
    de N5MHI Jon

    ReplyDelete
  8. Anonymous1/20/2016

    I see Icom posted new firmware 5 days ago (1/15/2016) that is supposed to improve the speech processor.

    ReplyDelete

.
Thanks for your comments, Comments may take a day to show up

Amateur Radio Users Support Group
https://groups.io/g/AmateurRadio

ICOM IC7300 IC-7300 SDR Transceiver
icom7300@groups.io
https://groups.io/g/icom7300

Icom 7610 Transceiver
Icom7610@groups.io
https://groups.io/g/Icom7610
.

Note: only a member of this blog may post a comment.