[Antennas] Re: From transmission lines to tuners;Simulator

2002年12月19日 12:20:52 -0700

The problem with most of these "Programs" is that they are like
statistics or Political Poles. You can feed them with all kinds of data
until you get the outcome you are looking for and then believe you have
come up with a "great revelation". Just like the "Gain" some antenna
manufacturers claim that they can backup with all sort of charts and
"theocratical data". 
I still say: Move away from your computers, Build some antennas, Run
some feedline, Hook up your tuner and your transmitter and get on the
air! See if the ham on the other end can hear you. After all "Ham
Radio" is supposed to be about "ON AIR" Communications. Or have you all
moved to "ON LINE" ? and forgotten how to "CQ" -.-. --.-?
73's de Jerry, K�EJF
On 2002年12月19日 09:03:23 -1000 "Jim Reid" <[email protected]>
writes:
> Interesting discussion. Of some help, might be to experiment
> a bit with a T network tuner simulator, one is available. Go to:
>> http://fermi.la.asu.edu/w9cf/tuner/tuner.html
>> You can adjust everything, including the Q of the components!
> Brief instructions are given, you will learn some stuff, hi.
>> Interesting that the highest efficiency in the network almost
> always will only occur when either the input or output series
> C element is set to its' maximum value. And in some cases,
> you will probably need more capacitance than a given tuner's
> components might have available!
>> The Simulator Set Up button allows you to change the maximum 
> values of the three components and their Q values. Initially the 
> capacitors are 250 pF, Q=2000 and the coil is 30 microH, 
> with Q=100. 
>> Wes has commented on this aspect in his post; see,in part:
>> > With decent components in the tuner (not all of them have 
> > them) the inductor will generally be the biggest contributor to 
> > insertion loss. This results from the fact that the unloaded Q 
> > of most capacitors is much greater that that of the inductor. 
> > 
> > Absent voltage breakdown in the components, it is the increased 
> > circulating current in the network that is the major contributor 
> to 
> > loss. With a give unloaded Q, the loss will increase when the 
> > loaded Q increases. With a network comprised of three variable 
> > elements there are in theory an infinite number of settings that 
> > will effect a match between two impedances. Each of them will 
> > have a different operating Q, so the object should be to adjust 
> > the network for a match with the lowest network Q.
>> Experiment with Q values with the Simulator to see what happens
> to the network efficiency.
>> 73, Jim KH7M
>>>> - - - 
>> Your moderator for this list is:
> Larry Wilson KE1HZ [email protected]
> _______________________________________________
> Antennas mailing list
> [email protected]
> http://mailman.qth.net/mailman/listinfo/antennas
>>
E. Jerold (Jerry) Forwood
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