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Re: [TenTec] Tentec Orion & Oscilloscope question

To: eric.sensi@skynet.be, tentec@contesting.com
Subject: Re: [TenTec] Tentec Orion & Oscilloscope question
From: "James C. Owen, III" <k4cgy_list@yahoo.com>
Reply-to: tentec@contesting.com
Date: Wed, 24 Nov 2004 07:12:45 -0800 (PST)
List-post: <mailto:tentec@contesting.com>
Hi Eric,
   There are many ways to monitor the waveform and a few have
been suggested ie: rubber duck, wire loop etc. However your
friend that attached the probe to the antenna lead with a T
connector has the best idea but maybe not the most mechanically
secure. The Heathkit monitor scope uses a series string of
capacitors from the antenna connector and switches up and down
the string to get the proper deflection for the power being run.
With a  variable attenuator on the scope you don't need this.
With the scope probe connected directly to the antenna you WILL
get a correct voltage reading as the 1 or 10 Meg ohm of the scope
is much greater than the 50 ohms of the antenna or dummy load. An
attenuator is not needed. If your antenna is close to 50 ohms you
can get a pretty accurate power reading using ohms law P= V(rms)
squared/R or P=V (peak to peak) X  0.353 /R. Only accurate if
antenna is a pure 50 ohm resistance but close for reasonable SWR.
 BTW don't worry if you have an open connection on the T
connector, it's such a small impedance bump at HF that the rig
will never see it. At 1296 Mhz, well that's another story. 

73 Jim K4CGY

--- Eric SENSI <eric.sensi@skynet.be> wrote:

> Hello all,
> As I'm not an electronic engineer but just an IT engineer :-)
> I'd like to know the better way to take the "modulated signal"
> to inject it
> into an oscilloscope ?
> I'm very new to this so be cute with me please.
> At the moment I have :

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