[Elecraft] high-power tuner

[Mike WA8BXN]

Ian, 
 
Weight comes into play in two ways. A heavier tuner will likely have less
loss due to less resistive loss by using larger diameter wire etc. But that
s not the issue in measuring the loss. 
 
As Fred mentions below, power fed into a tuner goes two places. One is out
to the load (antenna) and the other is heating the tuner (not a good thing).
One can measure how much a tuner warms up during use, that's due to loss in
the tuner. Just knowing the temperature change doesn't give the full answer
though. Lets say we measure an increased temperature of 10 degrees. Now if
we have a very heavy tuner, that would be more power lost in the tuner than
in a tuner that has the same 10 degree increase but is very small. Look at
it this way. It would take a lot more power to heat a gallon of water 10
degrees than to head a drop of water 10 degrees. 
 
To calculate the actual power loss in the tuner you would have to use the
right degree units, the right weight (mass) units and constants. You would
also have to heat insulate the tuner from the room so it doesn't cool off
during your measurement period. 
 
73 - Mike WA8BXN 
 
 
 
 
 
-------Original Message------- 
 
From: Ian Kahn - Ham 
Date: 3/9/2012 6:31:37 PM 
To: k6dgw at foothill.net 
Cc: elecraft at mailman.qth.net 
Subject: Re: [Elecraft] high-power tuner 
 
This probably shows my gross lack of knowledge of the physics involved 
Here, but what does the weight of the tuner have to do with its efficiency? 
 
73, 
 
--Ian 
 
Ian Kahn, KM4IK 
Roswell, GA 
km4ik.ian at gmail.com 
K3 #281, P3 #688 
 
 
On 3/9/2012 6:14 PM, Fred Jensen wrote: 
> On 3/9/2012 2:24 PM, WILLIS COOKE wrote: 
> 
>> If you need a tuner, your 
>> antenna does not meet this criteria so, what are you using to form 
>> your opinion? 
> Weigh the tuner, then transmit continuously, measure the temperature 
> rise, and when it's stable, calculate the heat loss [something to do 
> with Boltzman's Constant -- the tuner *is* painted black]. What doesn't 
> leave as heat must leave as RF. Did it years ago on a 10 KW FM 
> broadcast transmitter [4 ea 4-1000's], and it came within one percent of 
> the efficiency measured with the water-cooled dummy load. YMMV however. 
> 
> 73, 
> 
> Fred K6DGW 
> - Northern California Contest Club 
> - CU in the 2012 Cal QSO Party 6-7 Oct 2012 
> - www.cqp.org