Audio Settings for the Icom IC-7851 and the Electro-Voice RE27 N/D Microphone

ElectroVoice RE27 and Icom IC-7851

ElectroVoice RE27 and Icom IC-7851

In my initial impressions of the IC-7851, I indicated that setting up the transmit audio settings for use with my Electro-Voice RE27 N/D microphone had not been very difficult and that I was receiving very good audio reports with this combination.  In this post, I’ll explain how I set this up, and include some images.  As I have mentioned in other posts in this blog about audio set up (most recently where I interfaced the RE27 with the TS-990 I used for two years), your mileage may vary depending on your voice characteristics and other factors.  Don’t hesitate to play with these settings and get honest critique from fellow hams on the air.  I’ve found that using the monitor function on any radio never really gives you a true picture of how you sound, so enlist others on the air to help you.  I should also point out that there is no such thing as “one size fits all” when it comes to transmit audio.  The best settings for rag chewing will be a far cry from what works best when you are trying to bust a DX pileup.  So, know your voice and your intended application when setting up your transmit audio.  Tinkering, after all, is at the heart of amateur radio!

While I do work DX from time to time, I spend most of my operating hours talking to fellow hams or checking into nets.  I therefore rarely strive to have the “piercing” audio that some DX operators use.  When I do want to have a bit more punch, I will increase compression, narrow the bandwidth and eliminate bass, but this is the exception to how I normally operate.  This description of my settings is therefore probably not suited for a DX contest or similar application.  I have found that my settings generate very good reports from fellow hams who have told me that I have very “pleasing audio” and that “it sounds like you do in person”.

One more thing before we get into the settings.  Don’t eat your microphone!  A lot of hams believe that they must also touch the mic with their mouths when transmitting.  This can result in distorted audio and an RF burn if you have that problem in your shack, so remember to keep a respectable distance from your mic when transmitting.  I try to be at least two inches back when using my RE27.

I believe that any time you are setting up your transmit audio you must start with the mic gain and the ALC.  In fact, I constantly check to make sure that I am not exceeding the ALC zone on my meter.

IC-7851 ALC Meter

IC-7851 ALC Meter

Adjusting your ALC should be quick and easy.  Using a dummy load talk into your mic and adjust the mic gain so that you do not exceed the red ALC zone.  I have mine adjusted to peak at the end of the zone, but never exceed it.  For me, the mic gain setting is at the center (or twelve o’clock) to achieve this with the RE27.

IC-7851 Mic Gain Control

IC-7851 Mic Gain Control

After your gain is adjusted to peak, but not overdrive, your ALC, move on to the comp setting.  I run with the compression on and adjusted to the center (12 o’clock) position.  Again, your mileage may vary, but I have received very good reports with the compression on at this level.  Try it both ways and see what other hams say about your audio on transmit, but this setting with my mic did not produce any harshness in my transmitted audio.

IC-7851 Compression Indicator

IC-7851 Compression Indicator

The compression control is at the bottom of the radio.

IC-7851 Compression Control

IC-7851 Compression Control

You may have noticed that the compression indicator, above, also shows your transmit bandwidth (TBW) setting.  I run mine “wide” for this setup, but the 7851 allows you to choose narrow and midrange as well.  You might want to consider narrow for DX pileup work.  The good news is that all three TBW settings are adjustable in the settings for the 7851, so play with these and find the range that makes your audio sound the best.

IC-7851 TBW settings

IC-7851 TBW settings

After you adjust your TBW ranges to suit your operating needs, you will select wide, mid or narrow by holding for 1 second the selector adjacent to the compression/TBW indicator.  By the way, the TBW settings are accessed by pressing “set” (F-7), “level” (F-1) and scrolling down to the SSB TBW area. Once you’ve highlighted the setting you want to change, use the main VFO knob to change your settings.  Pressing DEF (F-4) will always change the settings back to default.

While you are in this part of the menu of the IC-7851, you can tweak the final setting to make your transmit audio sound great.  In addition to your TBW setting, the IC-7851 also has a simple equalizer to allow you to adjust the base and treble of your transmitted audio.  For this setup, I have mine set at Base +2 and Treble +1.  Again, your mileage may vary, but this works well for me with the RE27.

IC-7851 Base and Treble Control

IC-7851 Base and Treble Control

That’s it!  After working on all of these settings and receiving some helpful on-the-air input, I think I have achieved great sounding transmit audio with the IC-7851 and the EV RE27.

Oh, there’s one more thing if you are using the RE27.  Don’t forget that it has it’s own internal settings.  I played with these on the air with a ham friend and the settings shown in the following photo sounded best:

EV RE27 Settings

EV RE27 Settings

I hope this helps some of you get started with adjusting the audio on your IC-7851, but remember – it’s just a starting point!  Good luck and have fun with this truly first class radio.

73,

Bill – AB4BJ

P.S. Please post your experiences, settings, etc. in the comments section below.

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1 Response to Audio Settings for the Icom IC-7851 and the Electro-Voice RE27 N/D Microphone

  1. Jim says:

    I don’t understand how you are getting so much drive with the re 27 because the mikes own impedance is 150 ohms and the radio is 600 ohms ???? This is a miss match… Are you using a matching transformer, preamp, w2ihy ibox ???? You know if the mic is not used with the right input impeadence, the frequency response will suffer…

    My e mail is
    gearjamer468@gmail. com

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