Very interesting Geoff, thanks for the comments. I've deliberately not
installed those front end diodes in my K2.
As to the rain static, we've had very severe rainstorms in France as
I believe you too have experienced in the UK and this problem with rain
static I have never heard so bad, however this is a relatively new
antenna installation for me. The vertical element is constructed from a
42' length of coax using the braid as the radiator to provide a fat
wire, this radiator is suspended "inside" a Spiderbeam fiberglass pole
so is in no way in direct contact with the rain. I used to use a
butternut vertical (exposed aluminium vertical radiator) and didn't
notice rain static quite like this. Yes my feeling is the resistor bleed
would be better than the choke for the reasons you mention, still, I've
just been out and measured the resistance from the antenna to ground and
of course it reads zero Ohms, through the ATU I imagine so I don't quite
see why I need a further static bleed path, but I'll try it anyway.
Good to hear your K2 is a survivor, I've not had that horror, something
I dread, however at the base of my antenna is a spark gap arrestor and
then the auto ATU so...fingers crossed.
73,
Deni
F5VJC
Geoffrey Mackenzie-Kennedy wrote:
Deni,
My suggestion is that you use a resistor and not a choke. A choke at
some frequencies will become a series resonant L-C 'tuned' circuit,
and it is quite possible that the choke will resonate in or close to
one of the bands that you use. If that is the case you will loose
transmitter power heating up the choke, likewise the strength of
received signals reaching the receiver can be reduced. For static
bleeds I usually use 100k 2w carbon resistors, the old fashioned type
not carbon film, because the resistors *must* be non-inductive types.
My K2 survived a lightning strike to my 40m beam, but I think that the
combination of a coax spark gap out in the garden and an underground
coax feeder with 'surge loops' took out much of the sting. Back to
back diodes for protection against overload can create all sorts of
intermodulation problems if the diodes start to conduct, and for those
of us in Europe who share 40m with BC stations and using receivers
which cannot cope, overload is a problem but there are solutions.
Please contact me off list if you are interested.
73,
Geoff
GM4ESD
----- Original Message ----- From: "Deni" <[EMAIL PROTECTED]>
To: <Elecraft@mailman.qth.net>
Sent: Saturday, December 09, 2006 9:52 AM
Subject: [Elecraft] Static rain ?
I have recently been plagued by rain static on a new vertical antenna,
this is a 42 foot vertical fed at the base through an SG230 auto tuner,
and used on all bands. It seems I need a static bleed of some sort, a
choke or resistor. What is the best component to use in an outdoor
environment?
My junk box RF chokes look rather puny for this application, the
typical small 2.5mH RF choke.
Would a physically large, say 1 Meg resistor be more suitable ?
I thought the auto ATU would in itself provide a static bleed path,
but apparently not.
Is the K2 prone to front end damage due to this static charge? I do
not have the back to back diodes fitted (to prevent huge signal
overload)
Any thoughts, how have you solved this?
73, Deni
F5VJC
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