From: "Clemens Paul" <cpaul@gmx.net>
To: <rsgb_lf_group@blacksheep.org>
References: <CAKvcm2dbFX3d+jv04M_quU0Nwy=W-g5Jk5vxcN5SP87gg3PmzA@mail.gmail.com> <B507F4F2886F4488A919515FDD664BC3@gnat> <B4BD637350C7488DA8A8BAF58FC09D7D@AGB>
In-Reply-To: <B4BD637350C7488DA8A8BAF58FC09D7D@AGB>
Date: Sat, 16 Feb 2013 11:10:05 +0100
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Subject: RE: LF: Re: how to increase the Q of my loading coil?
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 Graham,

>I would think the  higher the  Q  the  higher the  losses in=20
>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  =20

>-----Original Message-----
>From: owner-rsgb_lf_group@blacksheep.org=20
>[mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Graham
>Sent: Friday, February 15, 2013 12:48 PM
>To: rsgb_lf_group@blacksheep.org
>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=20
>such a coil , the  bigger the  circulating  values ..  I look=20
>at 500  as the  next  band=20
>down  from   160  , differing  set of  rules  than  coming  up=20
>from  136=20
>..Top coil , takes  the  voltage out of the  shack / tuner=20
>house , while increasing the  vertical  amps , and yes, rain +=20
>Q =3D  problems !
>
>Ground is more  important than the  wire in the air or the=20
>tuner losses ....... all  the  old (now very old)  marine =20
>installations  only  had  30=20
>or 40  feet  of  vertical   wire  from the  radio  room  roof =20
>to the   top=20
>wire , but  a few  1000's   tons  of  iron  and  salt water  to  tune=20
>against
>
>GL-73-G..
>
>
>
>
>
>--------------------------------------------------
>From: "Alan Melia" <alan.melia@btinternet.com>
>Sent: Friday, February 15, 2013 1:28 AM
>To: <rsgb_lf_group@blacksheep.org>
>Subject: LF: Re: how to increase the Q of my loading coil?
>
>> Why? I think you might need to look at the priorities first.=20
>> Experience says you will not notice the difference unless you have=20
>> tackled the problem of ground and environmental losses first (as=20
>> Stefan has done) The improvement obtained by improving the Q of the=20
>> loading coil may probably only increase the efficiency by a=20
>minute amount.
>>
>> You say you have a Q of 200 now.... this indicates a bandwidth of=20
>> about 2kHz meaning you will probably need to retune across=20
>the band. A=20
>> Q of 400 to 500 should be possible but unless the reduction in RF=20
>> resistance is a substantial fraction of the Rloss it is=20
>wasted effort.=20
>> It also means that your tuning will be very weather=20
>dependent. I feel=20
>> that unles you have situation of Rloss <15ohms you will=20
>barely notice=20
>> the difference......except a "flighty" system, difficult to keep=20
>> 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=20
>> as well, and Litz is a devil to work with (note "proper" Litz has=20
>> strand numbers are twisted in powers of 3, anything else is just=20
>> bundled and will not achieve the theoretical advantage) If you miss=20
>> one strand out of the soldered connection of the Litz you=20
>will lose a lot of the advantage.
>>
>> Top loading may well turn out to be more effective, but it=20
>all depends=20
>> on your partcular location, and you need to make measurements of the=20
>> antenna systtem, and possibly the field it generates, not guess=20
>> (though that is very seductive :-)) but in my experience is usually=20
>> wrong!  )
>>
>> You are right in that the best way is to make incremental=20
>improvements=20
>> to the antenna, but be very critical, weighing the cost in=20
>effort and=20
>> cash for the improvement .......what works for others may=20
>not work for you.
>>
>> Best of Luck
>> Alan
>> G3NYK
>>
>> ----- Original Message -----
>> From: "Dimitrios Tsifakis" <dtsifakis@gmail.com>
>> To: <rsgb_lf_group@blacksheep.org>
>> 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=20
>>> consists currently of a 20-litre plastic bucket with standard house=20
>>> 240V electrical wire (with PVC jacket). I measured the Q=20
>and found it=20
>>> to be about 220 (XL is about 2 kohm). I do have  some Litz=20
>wire I can=20
>>> use. I also have a piece of large diameter (25 cm) storm=20
>water pipe,=20
>>> which I think is made of PVC.  Would you recommend using a=20
>PVC former=20
>>> or should I look for a more exotic material=20
>(glass/porcelain)? Would=20
>>> you think the inter-turn capacitance is very detrimental and some=20
>>> exotic winding technique would yield better results?
>>>
>>> I understand that ground losses are bigger in my case than the=20
>>> inductor losses, but I would like to address the inductor first.
>>>
>>> 73, Dimitris VK1SV
>>>
>>
>>=20
>
>
>
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