[1000mp] AMP Question

[w3jxp at comcast.net]

I use the internal tuner with my SB221 all the time. The SWR on 17, 15, and 12 meters is higher than I would like. There is no bad effects. The tuner does not "hunt". It tunes once and doesn't change again until I change bands. I also have used it with an older amp with a pasive input (no tuned circuits) and it worked just fine with that too. I think that using the built in tuner with an amp  will cause some sort of damage is an old wife's tale.

--
John Passaneau, W3JXP
State Collage, Pa.

-------------- Original message -------------- 
From: "Win" <w0lz at winlyn.us> 

> Not to draw this out, but I have to wonder if this is true in CW mode. 
> Modulation is either 100% or nothing. It would seem that the input Z would 
> remain the same and not cycle the tuner. Am I off base? 
> 
> Win, WoLZ 
> 
> 
> 
> ----- Original Message ----- 
> From: "Garry Shapiro" 
> To: "All about Yaesu 1000mp" <1000mp at mailman.qth.net> 
> Sent: Thursday, May 03, 2007 8:05 PM 
> Subject: Re: [1000mp] AMP Question 
> 
> 
> > The impedance is nonlinear--and so voltage and current do not have a 
> > constant relationship. 
> > 
> > Rob Atkinson wrote: 
> >> Hi, 
> >> 
> >> I guess I don't understand how the Z of a load can change with the power 
> >> delivered to it unless the components affecting the Z are underated for 
> >> the power. maybe i'm missing something? sorry. 
> >> 
> >> 73 
> >> 
> >> rob / k5uj 
> >> 
> >> 
> >> On Thursday, May 3, 2007, at 10:09 AM, Rod Elliott wrote: 
> >> 
> >>> Dick... 
> >>> 
> >>> I use a Mk5 Field to drive an AL-1200. No problems... works great. 
> >>> 
> >>> In my experience the SWR presented to the Field by the amp's input is 
> >>> always well below 2:1, even if the output of the amp is not perfectly 
> >>> matched. The Field has no problem with that. 
> >>> 
> >>> One precaution... do NOT use the Field's internal antenna tuner when 
> >>> driving the amp. (The amp's input impedance varies with drive level... 
> >>> you don't want the Field's tuner to strip its gears trying to follow 
> >>> your voice! ) 
> >>> 
> >>> 73 
> >>> Rod VE3UW 
> >>> 
> >> 
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