[Lowfer] Measuring TX loop current

[rick kirby]

Hi John,

Once again, thanks for the info . I have found a few meters around here that 
I am going to use to build the current probe. I am a little confused on some 
of the numbers though.
 I understand how you got 1.414 Amps from a 1 watt tx
(). Then if we also use the formula

(Vrms=)  ; .5 ohm antenna should give us .707 Vrms . How are you getting the 
5 volts  in your example to give the full 2 amp meter deflection?

 My antenna has a calculated Rac of 1.1 ohms However  Im getting 2 volts at 
the tx /antenna point. So my CALCULATED Rac must not be true. 2volts tells 
me its somewhere around 4 ohms? So, my Irms will be somewhere between  .5 
and .9 amps . I have a  1 amp dc meter Id like to use .With the 2 volts 
being max ( with Rac of 4 ohm ) and  1.04 volts ( ideal  with Rac of 1.1 
ohm ) ,a 200 ohm resistor should give me the full deflection  on a  0-1 amp 
meter. Is my math correct?



 Thanks again

  Rick  "PBO"  187.2 KHZ  /   QRSS 20












----- Original Message ----- 
From: "John Andrews" <w1tag at charter.net>
To: "Discussion of the Lowfer (US, European, &amp; UK) and MedFer bands" 
<lowfer at mailman.qth.net>
Sent: Monday, September 21, 2009 8:58 PM
Subject: Re: [Lowfer] Measuring TX loop current


> Rick,
>
> Some info:
> http://www.w1tag.com/RFA.htm
>
> John, W1TAG
>
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