Date: Wed, 11 Aug 2010 17:06:27 -0400
From: "Jim Tonne" <tonne@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 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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