Typo correction in the third line:
It must read **loaded** Q.
73
Clemens
DL4RAJ
>-----Original Message-----
>From: [email protected]
>[mailto:[email protected]] On Behalf Of Clemens Paul
>Sent: Sunday, February 17, 2013 10:30 AM
>To: [email protected]
>Subject: RE: LF: Re: how to increase the Q of my loading coil?
>
>Stefan,
>
>>So a high Q must be the goal, loaded or unloaded.
>
>Regarding unloaded Q I think there is agreement
>
>Regarding unloaded Q it depends HOW it is increased.
>As Jim has pointed out increasing unloaded coil Q also
>increases somewhat the overall system loaded Q by reducing
>circuit total R, this is perhaps what Graham was concerned about.
>But the benefit overweighs this small disadvantage.
>
>As a matter of fact with a matching network consisting of two
>reactive elements (L,C) or of one coil and an autotransformer
>as we have here it is not possible to choose a desired loaded
>Q (without the exception above).
>You get the lowest possible loaded Q anyhow and it is
>determined by the complex impedance of the antenna.
>But if you match with three reactive elements like a Pi- or
>T-Network then you can choose - within certain limits - the
>loaded Q by choosing the components values but it will be
>always higher than with two elements.
>High XL and XC components will result in a high loaded Q.
>In this case time the high loaded Q is detrimental for
>efficiency,losses and heat go up, so THIS way of increasing
>loaded Q should be avoided.
>
>The source resistance of a transmitter or a vector network
>analyzer decreases the overall loaded system Q which increases
>bandwidth.
>If you would feed the system by a voltage source the 3dB
>BW-points would coincide with a VSWR of 5,9.
>With a 50 Ohm source you have the 3dB points at a VSWR of 2,6.
>
>My apologizes if this all has been too long and boring. :-)
>
>73
>Clemens
>DL4RAJ
>
>
>
>
>
>
>>-----Original Message-----
>>From: [email protected]
>>[mailto:[email protected]] On Behalf Of
>Stefan Schäfer
>>Sent: Saturday, February 16, 2013 10:11 PM
>>To: [email protected]
>>Subject: Re: LF: Re: how to increase the Q of my loading coil?
>>
>>
>>Am 16.02.2013 11:10, schrieb Clemens Paul:
>>> [...]
>>> The higher the *loaded circuit* Q the higher are the losses in all
>>> involved components including the coil due to increasing
>>circulating currents.
>>> Given a certain circuit increasing the Q of its components
>>always will
>>> reduce overall losses of that circuit.
>>>
>>> 73
>>> Clemens
>>> DL4RAJ
>>
>>...however if the transmit power is kept constant, then the radiated
>>power is higher, due to the higher currents through the radiation
>>resistance. Thus the losses must be lower here.
>>It is not a constant voltage source, at least Dimitris' class E PA
>>isn't :-) So a high Q must be the goal, loaded or unloaded.
>>
>>73, Stefan/DK7FC
>>
>>
>>
>>-----
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>
>
>
>
>-----
>E-Mail ist virenfrei.
>Von AVG überprüft - www.avg.de
>Version: 2013.0.2899 / Virendatenbank: 2639/6104 -
>Ausgabedatum: 14.02.2013
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>
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