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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