[AMPS] Re: Static discharge caused NOISE

[Mike Sawyer]

I have at times had static build-up on my dipoles when there was just "dry"
air blowing across them during the winter months.  But the most common was
when the relative humidity was low and the air was blustery and speckled
with snowflakes.
Mike(y)
W3SLK
----- Original Message -----
From: Michael Tope <W4EF@pacbell.net>
To: Amps Reflector <amps@contesting.com>; Carl Clawson <ws7l@arrl.net>;
<W8JI@contesting.com>
Sent: Saturday, March 11, 2000 5:19 PM
Subject: RE: [AMPS] Re: Static discharge caused NOISE


>
> As Tom points out, DC grounding doesn't make much
> difference except in the case of electrostatic discharge.
> This can manifest itself in the form of rain or snow
> static. I recently saw an anecdotal account from Mike, N7MH
> up at the Stanford Radio Club, W6YX. Seems that all their
> KLM monobanders were wiped out by rain static in the ARRL
> CW contest while their Mosley PRO-67 stayed quite.
> I suspect, but I am not sure that this has something to
> do with the fact the KLM antennas use insulated elements
> whereas the Mosley elements are grounded to the boom.
>
> Mike, W4EF.................
>
>
>
> ----------
> From: Tom Rauch[SMTP:w8ji@contesting.com]
> Reply To: W8JI@contesting.com
> Sent: Saturday, March 11, 2000 9:59 AM
> To: Amps Reflector; Carl Clawson
> Subject: Re: [AMPS] Re: Static discharge caused NOISE
>
>
>
> > > All antennas should be DC shorted to ground at the receiver input
> > > because
> > of
> > > another reason: a sometimes much lower level of receiving back-ground
> > noise.
> > > de Hans
>
> DC grounded antennas are no different in noise level that DC leak
> antennas, or DC floating antennas with one exception.
>
> If the antenna charges up enough to arc something over, you will
> hear a loud POP in the receiver. Other than that, they are just as
> "quiet".
>
> My lowest noise receiving antenna for 160 meters are arrays of
> eight verticals and four verticals that are NOT dc grounded in any
> way at all. They are quieter than my arrays of Beverages, which are
> dc grounded.
>
> The reason the choke makes no difference is because the noise
> outside the frequencies where the receiver is tuned does not make
> it through the receiver, unless the receiver is very poorly designed.
> At the operating frequency, the coke is a high impedance and so it
> doesn't affect noise at that frequency at all.
>
> > And we certainly need to keep the choke on the tank side of the output
> > relay. Otherwise the tank floats during receive. With HV on there are
> > probably enough ions to charge it up and cause arcs.
>
> Yep, that annoying tick tic as the leakage in the blocking cap
> allows the variables to charge until the flash over! That can be
> shocking.
>
> > It makes sense to put the rf choke at the output side of the relay
> so that
> > it shorts anything that is not supposed to be there to ground -
> and, as
> > Hans has suggested, improve receiving back-ground noise.
> There is one
> > minor caution, though, in that the rf choke will drop in impedance
> at some
> > point and affect received signals.  A 2.5 mh choke would be fine
> through
> > 160 meters when using a low impedance antenna - but suppose
> you also use
>
> A 100 microhenry choke is enough for 160 meters in a 50 ohm line.
>
> > Sorry to digress, but it really has to do with design of power
> amplifiers
> > - and whether the rf choke should be hung on the output side of
> the relay.
>
> A choke should always be used on the tank circuit end of the relay.
>
>
> 73, Tom W8JI
> w8ji@contesting.com
>
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