Message-ID: <2025D63622D3474489049C563BA6B7AB@gnat>
From: "Alan Melia" <alan.melia@btinternet.com>
To: <rsgb_lf_group@blacksheep.org>
References: <570A7631.5050001@lineone.net> <DC91D7EF611642ADA1E361BF55CFCFC8@gnat> <570B6F37.8060402@lineone.net>
Date: Mon, 11 Apr 2016 11:10:46 +0100
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Subject: Re: LF: Re: Screening an LF Loading Coil
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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
>>>
>>
>>
>>
>
>