Message-ID: <570BD148.6020103@lineone.net>
Date: Mon, 11 Apr 2016 17:31:04 +0100
From: LineOne <dhchurch@lineone.net>
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To: rsgb_lf_group@blacksheep.org
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Subject: Re: LF: Re: Screening an LF Loading Coil
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It just sits on a corrugated steel roof which is grounded so a strap 
from keg to roof would also prevent any "diode" action when 
transmitting. I have just made s field strength device which will be 
installed if it ever stops raining so that may help.

Hugh, M0DSZ

On 11/04/2016 11:10, Alan Melia wrote:
> Hi Hugh,mmm that is quite a lot. Thinking of the copper lined tuning huts
> Decca and Orfordness I guess the keg should be grounded. ??
>
> Alan
> G3NYK
> ----- Original Message ----- From: "LineOne" <dhchurch@lineone.net>
> To: <rsgb_lf_group@blacksheep.org>
> Sent: Monday, April 11, 2016 10:32 AM
> Subject: Re: LF: Re: Screening an LF Loading Coil
>
>
>> Thank you Alan, the location inside makes your suggested spacing,
>> suspended and spaced on fibreglass rods. It needs more Tx testing as 
>> a few
>> brief reception reports were about 5dB down but that was probably
>> "propagation" conditions.
>>
>> Hugh.
>>
>> On 10/04/2016 17:04, Alan Melia wrote:
>>> Hi Hugh I think the rule of thumb (or at least the one I use) is 
>>> that the
>>> lowest turn should be at least half the coil diamter from the screen 
>>> base
>>> (which if too close will exhibit the properties of a shorted turn) and
>>> the diameter of the screen should be at least twice the diameter of the
>>> coil....more is better, but.......
>>>
>>> I think that should be OK with your coil size supported in the 
>>> middle of
>>> the keg, Hope you had the pleasure of emptying it :-))
>>>
>>> Alan
>>> G3NYK
>>>
>>> ----- Original Message ----- From: "LineOne" <dhchurch@lineone.net>
>>> To: <rsgb_lf_group@blacksheep.org>
>>> Sent: Sunday, April 10, 2016 4:50 PM
>>> Subject: LF: Screening an LF Loading Coil
>>>
>>>
>>>> A few years ago I found an aluminium beer keg which had been used for
>>>> mixing cement. As it was damaged it was no good returning it to the
>>>> brewery so I have just moved my LF loading coil into it and placed the
>>>> assembly outside on a corrugated steel roof. (Having the coil 
>>>> suspended
>>>> from the shack ceiling was not a good idea for the long term).
>>>>
>>>> I took the end off the keg, which is 370mm internal diameter, and the
>>>> coil is on a 130 mm former, likely to be no more than 160mm diameter
>>>> wound. The antenna is predominantly current fed so no voltage larger
>>>> than about 3kV is present.
>>>>
>>>> Has anyone tried this and am I likely to lose radiated power by 
>>>> reducing
>>>> the Q of the coil, the Tx output voltage and current are just the 
>>>> same?
>>>>
>>>> Hugh, M0DSZ
>>>>
>>>
>>>
>>>
>>
>>
>
>
>