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Re: [Amps] Measuring RF Power

To: amps@contesting.com
Subject: Re: [Amps] Measuring RF Power
From: Alek Petkovic <vk6apk@eon.net.au>
Date: Mon, 28 Mar 2005 20:54:52 +0800
List-post: <mailto:amps@contesting.com>
It is surely the best thread we have seen on this reflector in a long long 
time. Very comprehensive, informative and lots of fun to follow.

Thanks to all,
Alek. VK6APK

At 08:33 PM 27/03/2005, David Kirkby wrote:
>John and Mary Powell wrote in a different thread:
>
> >Is there a body of opinion out there that considers the above subject 
> has gone on far too long, or got out of hand. To me it appears as if 
> academic intransigence has got in the way of the Reflector dealing with 
> it's core business. I noted an earlier plea for an end to of 
> this  uninteresting topic, which evolved from a simple enquiry as to 
> accuracy of the Bird 43 Wattmeter.
> >
> >Cheers
> >John Powell. ZL1BHQ
> >_______________________________________________
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> >Amps@contesting.com
> >http://lists.contesting.com/mailman/listinfo/amps
> >
> >
> >
> >
>
>I'm not keen on a thread being split up for no good reason. Someone
>started this thread with the title 'Measuring RF Power' and so why
>ZL1BHQ starts a new thread 'MEASURING RF POWER' complaining about the
>original subject going on too long is beyond me. Most people use mail
>clients that that are capable of following a thread, and collapsing that
>down to one line. Most mail clients can be configured to automatically
>delete something with a particular title.
>
>So if you don't like a thread, just collapse it to one line in  your
>mail client, or do an automatic deletion, so it takes up zero space.
>Hence I decided to reply under the original thread, not the new one that
>has been started for no good reason.
>
>By starting a new thread, you have of course screwed it up for someone
>who was choosing to ignore the thread - now they have a second one to
>ignore. It also means when it is archived, someone interested in the
>subject will not see all the posts if they follow the thread, since it
>got split. Hence I'm not replying to the new thread, but under the old one.
>
>Now to address the comments of ZL1BHQ:
>
>I think you are right to suggest there is a body of opinion that
>consider the above subject has gone on for far too long. Those might include
>
>1) People who want just simple things, and don't wish to learn any more.
>
>2) People who were wrong, and don't wish to admit it.
>
>Sure, the thread is technical in nature, but less so than other threads
>that have appeared on here before, and with less mystique about it.
>
>However, there is also a body of opinion that thinks it is:
>
>1) Relevant to amplifiers. They do produce RF power, so measuring it is
>a pretty good idea.
>
>2) There is a 22.5% difference between the mean and RMS values of power,
>so the replies by some of "who cares anyway" seem odd, when there are
>quite a few who would care about a 22% difference in power levels.
>
>3) Within their grasp to understand.
>
>To follow the paper written in Laymens terms
>http://www.eznec.com/Amateur/RMS_Power.pdf
>you need the level of maths and electronics any radio ham should be able
>to handle if they put their mind to it.
>
>To understand the formal definition of RMS (using integration) a level
>of mathematics that I had learnt at school by about the age of 16 will
>suffice.
>
>4) A new topic discussed, and not the same old arguments being used
>about a topic that comes up again and again, year in and year out.
>
>It's also possible the topic has greater implications that some of you
>think. Someone wrote to me and said
>
>"Several years ago I did not realize, like many others, that there was
>no RMS power calculation that was useful. I ran into problems when
>looking at tube curves and trying to calculate power levels. Nothing
>came out quite right. Once I figured out the average power stuff then it
>all fell into place.  Same thing when trying to figure Peak envelope
>power. The rms power figure will screw things up. "
>
>Should a thread go too far "off topic" then I can see a point in
>requesting it is dropped, or moved to private email. But this is very
>relevant to RF amplifiers.
>
>--
>Dr. David Kirkby,
>G8WRB
>
>Please check out http://www.g8wrb.org/
>of if you live in Essex http://www.southminster-branch-line.org.uk/
>
>
>
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>http://lists.contesting.com/mailman/listinfo/amps

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