The power delivered to the load really is forward power minus reverse
power. You can see that by imagining that you disconnect the load
completely (infinite impedance) or short it out (zero impedance). That
means no power can be absorbed by the load.
The wattmeter reads equal forward and
Hi Folks:
Been reading this thread and just wanted to mention that the Elecraft W2
Interface program (
http://www.elecraft.com/software/W2/elecraft_w2_software.htm) shows both
forward and reflected power quite nicely.
73,
Carey, K2RNY
Rochester New York
Grid: FN13ef
On Tue, Jan 13, 2015 at 2:48
As well as not all the reflected power being re-reflected, the forward
power measured by the coupler is not the first time forward power, but
the sum of all the re-reflected power, as well.
--
David Woolley
Owner K2 06123
On 13/01/15 01:19, Fred Jensen wrote:
Well ... sort of. Some of the
Since this has historically been a can of worms, (it created a firestorm of
emails back in 2010 on a yahoo group between W5DXB, R. Fry, K1TTT, W7EL, and
Owen Duffy, then VK1OD) I want to introduce an authority on power measurement.
Agilent (now called Keysight) has a three part document that
And I started this thread by pointing that out, and saying wouldn't it
be nice if the W2 firmware could show Pf - Pr in the LED display. I
don't have screen space for yet another application.
On 13 Jan 2015 22:11, Carey Magee wrote:
Hi Folks:
Been reading this thread and just wanted to
I would like the W2 wattmeter to be able to display delivered power,
that is, forward power minus reflected power.
This would give a more accurate indication of power going to an antenna
when the SWR is not 1:1.
For example, if the SWR on the line is about 2.5 and forward power
indicates
On Mon,1/12/2015 7:56 AM, Vic Rosenthal 4X6GP/K2VCO wrote:
I would like the W2 wattmeter to be able to display delivered power,
that is, forward power minus reflected power.
You want N8LP's excellent LP-100A. I had lusted after one for quite a
while, and bought W6OSP's unit after he died for
I definitely want an LP100A, but I HAVE a W2, and while it is not as
accurate, I still would like to see the delivered power!
On 12 Jan 2015 21:12, Jim Brown wrote:
On Mon,1/12/2015 7:56 AM, Vic Rosenthal 4X6GP/K2VCO wrote:
I would like the W2 wattmeter to be able to display delivered power,
Vic,
What do you mean by delivered power? I presume you mean delivered to the
antenna (aka antenna system) but are you thinking power input to the W2 minus
all the losses. By all losses I mean all losses on transmission line due to
just plane old cable loss and higher losses due to higher
I would like the W2 wattmeter to be able to display delivered power,
that is, forward power minus reflected power. This would give a more
accurate indication of power going to an antenna when the SWR is not
1:1. For example, if the SWR on the line is about 2.5 and forward power
indicates 1.2
Well ... sort of. Some of the reflected power heats up the ATU and/or
PA depending on the match it sees [actually, some of the forward power
does too, tuners have forward losses]. Delivered Power is somewhat
difficult to calculate. Working into a matched, non-reactive load
[common for AM
Here is an experiment to show what I mean.
Take a transmitter and connect it to a 50 ohm dummy load through an antenna
tuner. Put a wattmeter between the transmitter and the tuner.
Now adjust the transmitter for 100 watts output and the tuner for 1:1 SWR.
The meter reads 100W forward and zero
What I want is just forward - reflected. Neglecting losses, this is what the tx
is 'delivering'. In real life somewhat less gets to the antenna.
Vic K2VCO /4X6GP
On Jan 13, 2015, at 3:19 AM, Fred Jensen k6...@foothill.net wrote:
Well ... sort of. Some of the reflected power heats up the
No. That is wrong. Forward and reflected are aspects of the standing wave, not
power delivered. —wunder, K6WRU
On Jan 12, 2015, at 8:53 PM, Vic Rosenthal k2vco@gmail.com wrote:
What I want is just forward - reflected. Neglecting losses, this is what the
tx is 'delivering'. In real life
I'm talking about forward minus reflected power. If you neglect losses, that is
how much power gets to the antenna to be radiated. A wattmeter that measures
forward power will be misleading if the SWR is high. My antenna has an SWR of
about 2.5:1 on 40 m. When the transmitter delivers 100 watts
All power ends in a load.
Forward and reverse power measures standing waves, but all those waves go into
some kind of load. Nearly all of it, if you are lucky, goes to the antenna. The
rest goes to heat. Forward and reverse is just a way to measure standing waves.
It does not mean the some
So why do I need an amplifier? I can just double my power by detuning my
antenna tuner!
Vic K2VCO /4X6GP
On Jan 13, 2015, at 6:54 AM, Walter Underwood wun...@wunderwood.org wrote:
All power ends in a load.
Forward and reverse power measures standing waves, but all those waves go
into
Sounds like a plan, Vic :-)
BTW -- did you manage to get that antenna repaired?
73, Phil W7OX
On 1/12/15 9:09 PM, Vic Rosenthal wrote:
So why do I need an amplifier? I can just double my power by detuning my
antenna tuner!
Vic K2VCO /4X6GP
On Jan 13, 2015, at 6:54 AM, Walter Underwood
You are implying that I can arbitrarily increase my power output by detuning my
antenna!
You are right that reflected power is re-reflected by the source, but there is
a sense in which the 'real' power output in my example is 1 kW.
Vic K2VCO /4X6GP
On Jan 13, 2015, at 2:46 AM, Phil Debbie
A better example would be to use a 100 Ohm dummy load and match it with a
tuner. Then measure the heat generated by the load. It should be 100W, minus
any losses in the tuner and transmission line.
wunder
K6WRU
CM87wj
http://observer.wunderwood.org/
On Jan 12, 2015, at 9:26 PM, Vic Rosenthal
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