[Elecraft] Feature wanted for W2 wattmeter

[Walter Underwood]

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 percentage of “reverse power” is disappearing into your power amplifier.

If you are running legal limit into forward power, you are quite likely running illegal power into the the antenna.

I was happy to get a C+ in my fields and waves class at Rice, but I do understand this stuff.

wunder
K6WRU
CM87wj
http://observer.wunderwood.org/

On Jan 12, 2015, at 8:32 PM, Vic Rosenthal <k2vco.vic at gmail.com> wrote:

> 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 to the line, there is about 120 watts forward and 20 watts reflected. I want a mode in which the wattmeter reads 100 watts in this situation.
> 
> Maybe 'delivered' is a bad choice of word. I mean something like 'power delivered by the transmitter'. Obviously it would take magic to know how much power gets to the antenna after losses!
> 
> Vic K2VCO /4X6GP 
> 
>> On Jan 13, 2015, at 12:08 AM, Phil Hystad <phystad at mac.com> wrote:
>> 
>> 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 SWR plus any loss in tuner or other devices between W2 and the aether.
>> 
>> Because, due to conservation of energy, that RF energy either goes out into Electromagnetic waves (radiated) or it ends up as heat-loss somewhere in the system.
>> 
>> And, given all that, I don't think any RF/SWR power meter on the market can measure "delivered power".
>> 
>> Or, are you talking about something else.
>> 
>> 73, phil, K7PEH
>> 
>> 
>>> On Jan 12, 2015, at 11:31 AM, Vic Rosenthal 4X6GP/K2VCO <k2vco.vic at gmail.com> wrote:
>>> 
>>> 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,
>>>>> 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 about half price. The
>>>> LP-100A supports two couplers, which can be deployed on the outputs of
>>>> both transmitters in an SO2R setup, or on input and output of a power
>>>> amp. The LP-100A measures the complex Z at the coupler, so it can
>>>> measure the input Z of the amplifier under dynamic conditions.
>>>> 
>>>> Now that I can measure power more accurately, I am able to run a dB or
>>>> more closer to legal limit when I want to for contesting.
>>>> 
>>>> 73, Jim K9YC
>>> 
>>> -- 
>>> 73,
>>> Vic, 4X6GP/K2VCO
>>> Rehovot, Israel
>>> http://www.qsl.net/k2vco/
>>> ______________________________________________________________
>>> Elecraft mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:Elecraft at mailman.qth.net
>>> 
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>>> Message delivered to phystad at mac.com
>> 
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Elecraft at mailman.qth.net
> 
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to wunder at wunderwood.org