This seems to have things really screwed up. Yes, the Bird 43 is a 5%
of F.S. accuracy instrument. The Bird 43P is somewhat less accurate,
although 5% F S with carrier, and more like 8% F S or so in peak mode.
In measuring a 100 watt radio with a 100 watt F S slug would seem to
be
On 8/21/2015 9:03 PM, Ken Kopp - K0PP wrote:
Bird accuracy is specified to be ± 5% of meter full scale ... a 100W
element would be a poor choice to measure a 100W output level. Take a look
at any Bird's meter scale. It's not linear and can be read with the most
accuracy to the left of center
In other words. you can read a less accurate value with greater precision.
On 8/23/2015 1:36 PM, Ken G Kopp wrote:
Bob,
The scale calibration --is-- compressed to the right of center,
--not-- to the left as you state, making the left portion expanded
and easier to read.
73!
Ken - K0PP
Bob,
The scale calibration --is-- compressed to the right of center,
--not-- to the left as you state, making the left portion expanded
and easier to read.
73!
Ken - K0PP
On Sun, Aug 23, 2015 at 2:14 PM, Bob McGraw - K4TAX rmcg...@blomand.net
wrote:
This seems to have things really screwed
On Sun, Aug 23, 2015 at 4:36 PM, Ken G Kopp kengk...@gmail.com wrote:
Bob,
The scale calibration --is-- compressed to the right of center,
--not-- to the left as you state, making the left portion expanded
and easier to read.
73!
Ken - K0PP
Easier to read, perhaps, but less accurate.
Thank you. I stand corrected on the point. Not physically having it
in front of me, I was recalling another power meter I use more
frequently. It is expanded up scale and compressed down scale.
73
Bob, K4TAX
K3S s/n 10,163
On 8/23/2015 3:36 PM, Ken G Kopp wrote:
Bob,
The scale
When I need to know accurate power readings my best instrument is
either scope and good 50-ohm termination, or using my HP432A mw power
meter. Its about 1/2 dB accurate. But +10mw is the highest scale so
you need several high power coaxial attenuators to measure
power. 40dB will permit
On Fri, Aug 21, 2015 at 11:19 PM, Edward R Cole kl...@acsalaska.net wrote:
When I need to know accurate power readings my best instrument is either
scope and good 50-ohm termination, or using my HP432A mw power meter. Its
about 1/2 dB accurate.
Isn't 1/2 dB accurate the same as 12 percent
Maybe really precise is a stretch when you're using scalar instrumentation.
Considering the money we put into rigs and antennas, the ~$500 price of the
DG8SAQ Vector Network Analyzer is affordable.
I can remember the days when I had to have some precision attenuation
measurements made on a
Bird accuracy is specified to be +/- 5% of meter full scale ... a 100W
element would be a poor choice to measure a 100W output level. Take a look
at any Bird's meter scale. It's not linear and can be read with the most
accuracy to the left of center scale. A 250W element is much better for
A comment here, has anyone thought to use a Bird 43P with a 100 watt HF
slug? Or maybe a TelePost LP-100a? Both are equally good regarding
power measurements but only when the load is 50 ohms resistive.
73
Bob, K4TAX
K3S s/n 10,163
On 8/21/2015 8:15 PM, Don Wilhelm wrote:
In a slightly
I have an LP100A as well as TX Mon for the P3. But, I also do admit that my
reason for having the LP100A is not to have an accurate reading of power but
rather to have a reasonable good indicator of power and SWR. I got the LP100A
long before I had my K3 or P3 so if I were doing it all over
Bob,
I use my Bird 43 terminated with a dummy load when the power level I
want to measure will give a good meter deflection with the slugs I have
available.
Like Don, I find the voltage method handy when working with QRP rigs,
since they barely deflect the Bird with any slug I have. I use
While the Bird wattmeters are highly respected, consider the following
with respect to any analog wattmeter:
The Bird can be as accurate as 5% of full scale - that means that with a
100 watt slug, a 5 watt potential error at any point on the scale.
Attempting to measure a 20 watt actual
So by your logic it would be best to measure one Watt using a 100W element.
On 8/21/2015 8:03 PM, Ken G Kopp wrote:
Bird accuracy is specified to be +/- 5% of meter full scale ... a 100W
element would be a poor choice to measure a 100W output level. Take a look
at any Bird's meter scale. It's
, August 21, 2015 8:25 AM
To: 'Mike Weir'; elecraft@mailman.qth.net
Subject: Re: [Elecraft] P3TXMON question?
Mike, to get RMS just multiple by .707
-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Mike
Weir
Sent: Friday, August 21, 2015 11:07 AM
Good morning to the group, my P3TXMON just arrived the other day and today it
was installed and it works and looks great! I do have a questionthe power
reading is Peak-Peak is there a way to switch to RMS? If not is it possible to
make a request to have this looked at by the Elecraft folks
, August 21, 2015 11:07 AM
To: elecraft@mailman.qth.net
Subject: [Elecraft] P3TXMON question?
Good morning to the group, my P3TXMON just arrived the other day and today
it was installed and it works and looks great! I do have a questionthe
power reading is Peak-Peak is there a way to switch to RMS
Mike, to get RMS just multiple by .707
-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Mike
Weir
Sent: Friday, August 21, 2015 11:07 AM
To: elecraft@mailman.qth.net
Subject: [Elecraft] P3TXMON question?
Good morning to the group, my P3TXMON just
The narrow bar is PEP (peak envelope power) with a long time constant.
The solid bar is effectively also PEP, but with a shorter time constant
so you can see what the modulation/keying is doing.
By the way, in the radio industry, the term peak is used in more than
one sense, which can be
Bill's information is entirely correct. Thank you for that clear
explanation.
Now back to what I think was the intent of the original question - even
if the terms were incorrect.
Hams commonly use two different considerations for power - PEP - Peak
Envelope Power - that is the peak power
Bill,
That's absolutely right. There's so much confusion about such things and
you have explained it very well. RMS can only ever be used as a value of
current or voltage, never power.
73 Stephen, G4SJP
On 21 August 2015 at 20:34, Bill Breeden breede...@cableone.net wrote:
It's important
It's important to remember that RF power expressed in watts is always
based on RMS values. If RF watts are calculated by measuring the
voltage across a known load, the voltage must be expressed as an RMS
value to correctly calculate the power in watts. Watts are watts.
There is no such
In a slightly related note - for those who are using an oscilloscope to
measure the RF voltage at the output, instead of converting everything
to RMS and doing the power calculation, I can give you a shortcut. The
formula for power by observing the RF voltage across a 50 ohm dummy load
is
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