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Subject: [TowerTalk] THRULINE MODEL 43
From: (Tom Rauch)
Date: Mon, 01 Jun 1998 09:26:23 +0000
To: <>
> Date:          Fri, 29 May 1998 17:36:27 -0700
> From:          VE3KKM <>
> Subject:       [TowerTalk] THRULINE MODEL 43
> To:  
> Reply-to:

> meter that was given to me 4-5 years ago.On SSB the output on the
> transmitter shows 100 watts,but the model 43 shows only 20 watts on
> voice peaks.At higher power with the amplifier loaded at 1kw(or close
> too) the model 43 shows 400 Watts on SSB voice peaks.With a continous
> carrier it shows the same output as on the transmitter.

> Why does the watt meter show such low output on SSB,as comparied to
> transmitter output? 

Virtually all transmitters use a meter that responds to peak 
envelope power.

The Bird (and many other meters) responds to average envelope power.

>Is the low output measured on the bird the actual
> output?

It is the average envelope power. 

You need a Bird 43P, or a conversion kit, to read peak envelope 

The normal difference between peak envelope power and average 
envelope power ranges from about 6:1 to 3:1 for typical voices and 
transmitter characteristics.  You're in that ball park, with a 5:1 

But the difference between the amplifiers tuned carrier output of 
1000 watts and a Bird reading of 400 watts (a ratio of 2.5 to 1)  
indicates you are overdriving or mistuning the PA. The ratio should 
be MUCH higher, so you can be pretty sure you are clipping in the PA 
and splattering.

73, Tom W8JI

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