05-27-2010, 10:38 AM
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Join Date: Apr 2005
Location: Nova Scotia,Canada
| | Yaesu FT-857/897 AM operation.
-857/897 radios have a hidden menu. It is turned OFF by factory default. You may enable it by entering the regular menu mode by pressing the [FUNC] button for a second or so. Advance to menu item #1 and rotate main tuning dial so that the display says ON. Press [FUNC] button again to exit menu mode. Turn radio OFF. Press and hold buttons [A] [B] and [C] under the display while turning radio back on. The radio will emit a series of beeps and enter the hidden service menu mode. CAUTION: DO NOT MAKE ANY ADJUSTMENTS TO ANYTHING IN THIS MENU WITHOUT FIRST COPYING THE DEFAULT SETTING! THIS IS A SERVICE MODE AND THE SETTINGS ARE UNIQUE TO EVERY RADIO.
Advance to menu item #60 which is the AM carrier level ALC control. The display should show something like:
AM-CAR-LEVEL 125 AM 21.225.13
Note that the value of 125 is unique and will change from one radio
to the next. Mine was set to 142. While monitoring the ALC level
press the PTT and adjust the main tuning knob for little or no
ALC indication. This will allow the carrier to peak to something near
100-120 watts like it should. I had to set my radio to 96. The
problem is that the factory settings limit the carrier to 25-30
watts and the ALC will not allow it to peak any higher as it
should be able to do. After making the adjustment press the
[FUNC] button again to exit the setup for that menu item and
turn the radio OFF. Turn the radio back on normally and enjoy
MUCH better quality AM transmissions. I find it best to not
use the processor or if you do use very light processing on AM.
You may also find it useful to set the radio to use the DSP settings
for TX as well as that allows you to tailor the high and low
limits of your audio.
Prior to making this simple change I had very muffled audio
on AM. After, I had MUCH improved audio that was no longer
muffled and the power meter actually
moved with modulation.
Above all keep the carrier to no more than 25-30 watts.
Knowledge is knowing that a tomato is a fruit, but Wisdom is knowing not to put it in a fruit salad.