[ICOM] Mic gain on the 706 MKIIG

[David J. Ring, Jr.]

Jack,

You probably know all of what I'm going to write here - but I'm sure there 
might be one on the list who might learn something from it.  If you know it 
already - as many of us do - just skip over it.  Sometimes people tell me 
things I already know, but I've learned that that is much better than people 
NOT trying to help you!   They just didn't know what things I already knew. 
If you have more to add, please do - I always like to learn little labor 
saving tricks of the trade.

When you put your microphone on the bench, there will be several variables.

There will be the deviation adjustment.
There will be the typical microphone setting that you use on SSB.
There is the DTMF output from the microphone.

I don't have a '706, but I know the problems I've had in the past.

I use a simple method of setting the microphone gain on SSB.

I take the processor off.
I use the monitor function and wear a good set of headphones, and I turn up 
the gain so that I can hear my voice in the headphones.  I listen carefully 
for distortion.  Sometimes headphones will just distort slightly with strong 
audio, so back off on the monitor output to confirm that it is distortion 
from the transmitter.  Before you leave this setting - try some loud 
speech - like when you might get excited.  See if you hear distortion.  If 
you do back the audio gain down until the distortion disappears.  I back 
down the gain a bit more than needed - because I get more excited on the air 
than I do with test equipment.

Now that you have this position - you're ready to go on the other modes!

I've found that a very large majority of people overdrive their microphones. 
Most that I've talked to have never listened to the monitor feature of the 
radio.

Try making a QSO on SSB especially with a local who knows your voice - he 
should report your audio sounds "awesome".

Now go on a FM repeater with the same ham if possible. Talk in the same 
voice.  Ask the other fellow how it sounds.  If the deviation control 
(inside) is set too high, it will sound rough and full of crackles on loud 
voice peaks.  If it does you have to decrease the deviation control.

I've done this "in the field" by just having the other ham tell me what my 
audio sounded like as I VERY slowly (and I mean very) carefully (1/30 of a 
turn at a time) adjusted the deviation control.

It is much easier to take this radio to a 2-way radio shop where they have a 
communications monitor.  If you know a local ham who has the shop, he 
probably will let you speak into the microphone as he adjusts the deviation.

But (and I forgot this!) have him re-adjust the DTMF (touch tone) pad in the 
microphone.

I cranked down on the deviation only to forget to increase the gain of the 
DTMF output.

Some local repeaters have a DTMF test function which tests both for 
amplitude and frequency tollerence of the signals.  If your local repeater 
guru has put one of this in (ask him) use it.  It will give you an 
indication about your DTMF levels.

I generally adjust the DTMF for 90% of the deviation - some people do more, 
but I have never seen the reasoning behind doing 100% as some do.  No wonder 
most repeater owners filter out DTMF tones - they're too darned loud.

While you have a service monitor working on your radio - check the PL tone 
levels and also any "burst tones" that might be on the '706.

I hope this is helpful - if even slightly - to you or others on the list.

73

David J. Ring, Jr., N1EA

=30=


----- Original Message ----- 
From: "Jack - K4WSB" <K4WSB at arrl.net>

It's been my experience even those of us who have been licensed for over 45
years and have been on 2 meters for over 30 years have the same problem
with the 706!

Maybe I took comment wrong but the fact remains the mic gain must be
changed every time I switch from SSB to FM.  This happened using the stock
mic, the DTMF mic and my Heil Traveler.

My friend also has the problem with his 910H.  I have not had my radio on a
bench and that will be the next step to check out the deviation setting.  I
do not have the equipment or it would have been done already.

For a radio to have this issue seems to me as a design flaw.  The 706 was
designed as a mobile and to have to change settings while driving is
inconvenient to say the least  (note to the peanut gallery: YES, I know you
should pull off the road first!)

No one mentioned if this is also an issue with the 7000.  I just heard the
control mic on the 7000 does NOT send DTMF and that yet another mic has to
be used if you want to access IRLP or echolink nodes.  If this is true that
really is a stupid design.