[Amps] Fw: Needed, quality watt meter

[Roger]

On 8/11/2010 6:46 PM, Jim Thomson wrote:
> Date: Wed, 11 Aug 2010 17:06:27 -0400
> From: "Jim Tonne"<tonne at comcast.net>
> Subject: Re: [Amps] Fw: Needed, quality watt meter
>
>    
>>>> With the bar graph, tune up is a breeze.
>>>>          
> Regarding using a "digital" display for making
> adjustments, Jim has just pointed out an interesting
> thing.
>
> The BEST displya for adjusting stuff is the kind of
> display (meter) with a moving pointer.   Right behind
> that is the bargraph.  And running a distant third in
> terms of ease of use is the kind of display that
> shows you numbers.  Our minds just don't react to
> that like they do to an "analog-like" display.
>    
I don't believe it's a case of our minds nor reacting to digital 
compared to analog.
The digital although it may...or may not be precise, has no continuity 
to it. There is no flow to the digits and if the what ever we are 
reading is changing  rapidly the display following it loses 
representation. In a 3 digit display you may not be able to read 
anything in the least significant digit and possibly at times even the 
second digit. Sometimes it's impossible to tell if it's going up or 
down. OTOH ripple often shows up as a dithering of the last digit, or 
even digits. That's something an analog meter ignores.

73

Roger (K8RI)
> I am talking here about making adjustments, not
> about "taking a meter reading."
>
> - JimT   W4ENE
>
> ##  well,  I have  peak reading bird rack mount meter's, plus the peak reading Coaxial dynamics eq of a  bird 43.
> That's a CD model 83,000  pep meter.
>
> ## The problem with the peak reading CD meter's is... they are fast attack..and VERY slow decay !   This makes pulse
> tuning any amp a real bitch  of a job.   IE:  you hit a peak while tweaking the tune control, and the peak is sustained on the
> wattmeter.  meanwhile you have tuned past that point, and the  pep meter is lagging behind.   The pep meter catch's up, and
> power out is now down.
>
> ##  I have 4   AS   powe-rmaster's  now.  One coupler on  each side of the big amp.  I then parallel two identical displays..which go
> to the coupler on input of big amp.    And repeat for 2nd set of display's..wired to  coupler #2, on output side of big amp.
>
> ## one input and one output display is rack mounted.... and will eventually go in the shop.    2nd pair of displays  goes in shack. Both
> input displays  read identical info... and ditto with output displays.   Then when testing amps in the workshop, I have metering in two locations.
>
> ## I find the bar-graph  on the AS power-master, VERY easy to use, to tune any amp.  It's a snap really, and makes the bird/CD pep meter's look
> like a sick puppy.      The powermaster has  3 x AUTO ranges for the bar graph, so you always get max resolution.  On top of all that,  you can pick from
> FOUR groups of  auto ranges...like
>    50-250-  1250
> 100-500-  2500
> 200-1000-3000
> 400-2000-3000
>
> All you do is pick one of the 4 x ranges that suits ur needs.   Once the amp is peaked for max on the huge bargraph, you can then look  at the numerical display
> and tweak the last 1-2 watts, which is most you will get more...using the numerical display.   BTW,  above 100 watts, the numerical display is in 1 watt increments.
> Below 100watts... it reads in .1 watt increments.... like   99.9 w    or  46.7 w   etc.
>
> The AS powermaster couplers are far more accurate than any of my bird/cd slugs [all new].  Heck, the powermaster has an option to read  net power if u want
> frwd - rvs power].   For those of you that have manual ant tuners,   the swr dipping mode, using the bargraph is a godsend, makes tweaking any tuner a  3 x sec event.
> Numerical swr display reads out to 2 x decimal places... like   1.01 :1     or  1.24: 1    etc.   I had jay install RG-393  coax in my 3 kw coupler.
>
> The bird/cd meters  will work good, when pulse tuning any amp... but only when the pep mode is shut off, and you are using average mode.  Good for tune up... but then
> the problem is... you don't know what ur pep power out is.... until u switch back to pep mode again.  If any swr present, you have to subtract rvs power from forward power.
>
> To do the bird/cd right, you really require  a double line section, and two slugs.   And pep boards on both of em.  After all that, you still have no hi/lo power alarms, and no
> high swr alarms etc.  The bird /cd are only accurate IF the slugs are calibrated.  Even then, they are only within their 5%  spec..when the meter is at the top end of it's scale.
> The CD pep board is worse  at  +/- 7%..... and the bird pep board is  worse still... +/- 8%.
>
> The  10/20 kw  power-master couplers  work equally superb.
>
> later.... Jim   VE7RF
>
>
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