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Date: Tue, 11 Oct 2011 09:52:38 +0200
From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= <Stefan.Schaefer@iup.uni-heidelberg.de>
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To: rsgb_lf_group@blacksheep.org
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In-Reply-To: <Pine.LNX.4.64.1110102222310.10824@plato.ucs.mun.ca>
Subject: Re: LF: VX9MRC QRV 507.77 kHz/ Arcing relays &c.
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Hi Joe,

Maybe you can switch a series LC circuit which is resonant at 1850 kHz 
parallel to the 0.2 mH coil? For example 200 pF/37uH. You must then 
re-adjust the 0.2mH coil a bit. Can be calculated or done in an 
experimental way ;-) Then it would run without a relay.
But do you really have 50 kV on that 200uH coil at 500 (137) kHz? That 
would mean 80 (290) A antenna current...?

73, Stefan/DK7FC

Am 11.10.2011 03:11, schrieb jcraig@mun.ca:
> Hi Alan, Group.
>
> Thank-you for the reply. Multiple contacts in series were 
> considered... but the gap has to
> increase by orders magnitude!  How much gap will I need for 50 kV?
>
> Your spiral pie story was most enlightening.  My pies are ~35 turns of
> 4mm litz about 37 cm diameter with L=0.24 mH. A stack of 4 yields
> 3mH.  Each pie has ~23 metres of litz.  Do you think this is will give
> the most L for the least length of litz?
>
> VX9MRC is still sending the 8 WPM beacon as yours truly looks at a fried
> relay...
>
> Cheers
> Joe
>
> On Tue, 11 Oct 2011, Alan Melia wrote:
>
>> Hi Joe, why not stick two sets of normal contacts in 
>> series....doubles the
>> gap :-))
>>
>> Alan
>>
>> ----- Original Message -----
>> From: <jcraig@mun.ca>
>> To: <rsgb_lf_group@blacksheep.org>
>> Sent: Monday, October 10, 2011 11:54 PM
>> Subject: Re: LF: VX9MRC QRV 507.77 kHz/ Arcing relays &c.
>>
>>
>>> Hello Hartmut, Group.
>>>
>>> Good to hear from you again, Hartmut.  Thank-you for  the report.
>>>
>>> The beacon is on again, but there was some trouble: to use the tower
>>> on 160m the 500 kHz tuning coil (0.2 mH) is shorted by a relay. The
>>> N.O. contacts on this relay arced over.  Perhaps a high voltage 
>>> (vacuum)
>>> relay would help?
>>>
>>> This  problem will be much worse on 137.777 kHz with the higher 
>>> voltage.
>>> I have some spiral wound 4mm (Decca) litz to make up the 3 mH for that
>>> project.  (The spiral winding was inspired by G3NYK's experiments with
>>> tuning coils on his web page.)
>>>
>>> 73
>>> Joe
>>>
>>> On Mon, 10 Oct 2011, Hartmut Wolff wrote:
>>>
>>>> Am 2011-10-09 23:50, wrote jcraig@mun.ca:
>>>>> Dear Group,
>>>>> Reports on the 8 WPM CW beacon will be appreciated!
>>>>> 73
>>>>> Joe VO1NA
>>>>
>>>> Attached a screenshot of the 8wpm signal. The signal came up at about
>> 23:20
>>>> and faded out at about 7:35. The strongest part was between 
>>>> 04:00-06:00
>> UTC
>>>> -- 
>>>> 73
>>>> Hartmut
>>>> www.h-wolff.de
>>>> Locator: JO52hp
>>>>
>>>
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>>>
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>>
>>>
>>
>>
>>
>
> This electronic communication is governed by the terms and conditions at
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