[Top] [All Lists]

Re: [TowerTalk] Was "43ft Vertical Feeding Question and Balun Type"

To: Richard Thorne <>
Subject: Re: [TowerTalk] Was "43ft Vertical Feeding Question and Balun Type"
From: jimlux <>
Date: Sun, 23 Nov 2008 17:42:36 -0800
List-post: <">>
Richard Thorne wrote:
> With the CG tuner you would have to take the amp off line manually, then 
> key your rig so a tune cycle would take place.  I'm sure the tuner 
> instructions state to do this at low power 10-20 watts.  Most modern 
> rigs reduce the power when they see a high swr, so you normally wouldn't 
> have to reduce the power manually.

This doesn't always work.. the timing of the foldback of power and the 
internal tuning algorithm can result in interesting chattering effects. 
The tuner tries to minimize the reflected power and changes the Z, just 
as the rig reduces the power being fed to the tuner, so the tuner gets 
fooled, etc.

What I do with my IC7000 and SGC tuner in the car is set the rig up for 
low power, then step through every few kHz, hit the PTT, and let the 
tuner find a match and store it.  Then,when I'm back to full power, it's 
not trying to tune each time, just read the Tx frequency.  That's pretty 
foldback immune (i.e. the Tx sees reflected power for a fraction of a 
second, during which time the tuner measures the frequency and resets to 
the stored setting)..

Of course, this is why the software in the tuner is important, eh?

> Once the tuner is tuned you could hit the amp operate/standby switch and 
> start running with high power.
> I would probably forget to turn the amp off in the heat of the moment, I 
> would rather the tuner interrupt the ptt line so tuning is totally 
> automatic.



TowerTalk mailing list

<Prev in Thread] Current Thread [Next in Thread>