Re: LF: Re: M0BMU - any chance of some new ERP estimates please?

[Andy Talbot <andy.g4jnt@googlemail.com>]

So go on:  argue against the Rrad (an exact figure derived from basic electromag theory) and Rloss (easily measurable, called Ohms law) way of getting antenna efficiency.  

 

Or  ERP =   I^2 . Rrad   where I is measurable.

 

Only uncertainty in any of these techniques is the effective height of the antenna used to get Rrad, but absolute worst case, can only ever lead to 6dB error.  The difference between no top hat and an infinite top hat

Andy
www.g4jnt.com

2010/1/21 mal hamilton <g3kevmal@talktalk.net>

Rik's figures are always exaggarated could be plus/minus 100 dB either way. Recent dipole gain figures from Rik indicated that I am running 400 mw erp.

    whereas some months ago his estimate on received signals from me was 20 plus watts and here there has been no changes here same old TX/ANTENNA.

 Figures from others over the years have been totally wrong, ALL GUESSWORK, think of a figure juggle it about and publish.

In the amateur context depending on site,  theory and practical are often a long way apart.

When I have queried these figures there is NO RESPONSE

G3KEV

   

 

 

----- Original Message -----

From: Roger Lapthorn

To: rsgb_lf_group@blacksheep.org ; James Moritz

Sent: Thursday, January 21, 2010 5:04 PM

Subject: LF: M0BMU - any chance of some new ERP estimates please?

Dear Jim,

Following the discussion on the LF reflector in the last 24 hours, I wonder if we could use your experience and expertise to estimate the most recent ERP levels for G4JNT, G3ZJO and G3XBM please. Based on Rik's figures we've some doubt whether Andy G4JNT is being a little optimistic or whether Eddie and I are being pessimistic or whether the truth is somewhere in between.

Would much appreciate this. Thanks

73s
Roger G3XBM

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