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Static rain ?

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Deni F5VJC

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

--
73, Deni

F5VJC

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Don Wilhelm-3

RE: Static rain ?

Deni,

I would be tempted to wind my own RF Choke. Use a large ferrite core
(FT240-61 for instance) and wind as many turns of 20 guage wire on it as you
can. Connect it from the vertical to ground and see if it works.

Unless you have some unusual condition where the static noise is creating
huge voltages at the antenna input, it is not likely to damage the
receiver - the annoyance of listening to it is the baggest problem. This is
noise pickup from static discharges at the antenna rather than a direct
discharge of static into the receiver.

The diodes in the T/R switch will offer some protection for the K2 receiver.

73,
Don W3FPR

> -----Original Message-----
>
> 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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Geoffrey Mackenzie-Kennedy-2

Re: Static rain ?

In reply to this post by Deni F5VJC

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" <[hidden email]>
To: <[hidden email]>
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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Deni F5VJC

Re: Static rain ?

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" <[hidden email]>
> To: <[hidden email]>
> 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
>
>
>
>