Graham,
>I would think the higher the Q the higher the losses in
>such a coil , the bigger the circulating values .
I would think this thinking is wrong. :-)
The higher the Q of the coil the lower are of course the losses in such a
coil.
We are dealing here with the *unloaded* Q of a component.
But when we talk of the *loaded* Q of a (R)LC circuit, then your reasoning
is correct.
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
>-----Original Message-----
>From: [email protected]
>[mailto:[email protected]] On Behalf Of Graham
>Sent: Friday, February 15, 2013 12:48 PM
>To: [email protected]
>Subject: Re: LF: Re: how to increase the Q of my loading coil?
>
>I would go along with that
>
>I would think the higher the Q the higher the losses in
>such a coil , the bigger the circulating values .. I look
>at 500 as the next band
>down from 160 , differing set of rules than coming up
>from 136
>..Top coil , takes the voltage out of the shack / tuner
>house , while increasing the vertical amps , and yes, rain +
>Q = problems !
>
>Ground is more important than the wire in the air or the
>tuner losses ....... all the old (now very old) marine
>installations only had 30
>or 40 feet of vertical wire from the radio room roof
>to the top
>wire , but a few 1000's tons of iron and salt water to tune
>against
>
>GL-73-G..
>
>
>
>
>
>--------------------------------------------------
>From: "Alan Melia" <[email protected]>
>Sent: Friday, February 15, 2013 1:28 AM
>To: <[email protected]>
>Subject: LF: Re: how to increase the Q of my loading coil?
>
>> Why? I think you might need to look at the priorities first.
>> Experience says you will not notice the difference unless you have
>> tackled the problem of ground and environmental losses first (as
>> Stefan has done) The improvement obtained by improving the Q of the
>> loading coil may probably only increase the efficiency by a
>minute amount.
>>
>> You say you have a Q of 200 now.... this indicates a bandwidth of
>> about 2kHz meaning you will probably need to retune across
>the band. A
>> Q of 400 to 500 should be possible but unless the reduction in RF
>> resistance is a substantial fraction of the Rloss it is
>wasted effort.
>> It also means that your tuning will be very weather
>dependent. I feel
>> that unles you have situation of Rloss <15ohms you will
>barely notice
>> the difference......except a "flighty" system, difficult to keep
>> peaked, and possibly a number of fried PA devices when it goes wrong.
>>
>> Litz will improve the Q slightly, coil form factor needs to be right
>> as well, and Litz is a devil to work with (note "proper" Litz has
>> strand numbers are twisted in powers of 3, anything else is just
>> bundled and will not achieve the theoretical advantage) If you miss
>> one strand out of the soldered connection of the Litz you
>will lose a lot of the advantage.
>>
>> Top loading may well turn out to be more effective, but it
>all depends
>> on your partcular location, and you need to make measurements of the
>> antenna systtem, and possibly the field it generates, not guess
>> (though that is very seductive :-)) but in my experience is usually
>> wrong! )
>>
>> You are right in that the best way is to make incremental
>improvements
>> to the antenna, but be very critical, weighing the cost in
>effort and
>> cash for the improvement .......what works for others may
>not work for you.
>>
>> Best of Luck
>> Alan
>> G3NYK
>>
>> ----- Original Message -----
>> From: "Dimitrios Tsifakis" <[email protected]>
>> To: <[email protected]>
>> Sent: Friday, February 15, 2013 12:31 AM
>> Subject: LF: how to increase the Q of my loading coil?
>>
>>
>>> Hello group,
>>>
>>> I would like to increase the Q of my loading coil for 475 kHz. . It
>>> consists currently of a 20-litre plastic bucket with standard house
>>> 240V electrical wire (with PVC jacket). I measured the Q
>and found it
>>> to be about 220 (XL is about 2 kohm). I do have some Litz
>wire I can
>>> use. I also have a piece of large diameter (25 cm) storm
>water pipe,
>>> which I think is made of PVC. Would you recommend using a
>PVC former
>>> or should I look for a more exotic material
>(glass/porcelain)? Would
>>> you think the inter-turn capacitance is very detrimental and some
>>> exotic winding technique would yield better results?
>>>
>>> I understand that ground losses are bigger in my case than the
>>> inductor losses, but I would like to address the inductor first.
>>>
>>> 73, Dimitris VK1SV
>>>
>>
>>
>
>
>
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