[-] [ICOM] Amp tuning

[W8AEF]

The tuner in the PRO III is tuning the radio to the load the amplifier 
represents to it.  And as you adjust the amplifier's tuning that load will 
change.

I believe that Icom recommends you not use the tuner in the Pro III when you 
are driving an amplifier with it.

I use RTTY to tune my amplifiers, but I keep the key down interval short.  I 
created a chart for tuning presets when the bands were dead (daylight for 
160 & 80, night for 30 and up) and I use this preset chart when QSYing to 
avoid generating QRM.

I suggest you bypass the amplifier, disable the PRO III tuner, and adjust 
your MFJ Versa Tuner for best SWR.  Make a note of the settings on the MFJ. 
Then enable the amplifer and adjust it's tuning and loading for maximum RF 
output and make a note of these settings.  These settings will be your 
presets for your amplifier and tuner for that frequency.

de Paul, W8AEF


----- Original Message ----- 
From: "Bob Bennett" <bbbnntt at optonline.net>
To: <icom at mailman.qth.net>
Sent: Wednesday, September 13, 2006 7:09 PM
Subject: [-] [ICOM] Amp tuning


I have an Icom 756 Pro III and just hooked it up to my old Detron
GLA-1000 amp. I have two questions:

   1. The station has a g5r3 that the Icom automatic tuning feature has
      been tuning quite well. Now that I have the amp do I need to use
      another tuner between the amp and the antenna, or does the Icom
      tuner tune the G5RV through the amp. The SWR reading on the
      radio’s meter is showing an SWR between 1.0 and 1.5. The meter on
      the MFJ Versa Tuner (coax direct) in line after the amp is showing
      an SWR as hi as 3.0.
   2. When tuning my amps, I have been tuning them using FM. I have
      never been confident with hellllloooooo on ssb and my whistling
      skill is as bad as my singing. It this (FM tuning, not singing)
      harmful to the amp?

Bob/KG2RP