STATIC BUILDUP ON ANTENNAS/Cure device

STATIC BUILDUP ON ANTENNAS/Cure device

Post by Radioma » Sun, 10 May 1998 04:00:00

Sometimes you get a crackling sound on your antennas...particularly during snow
storms (I'm told even worse in dust storms)...it may be static buildup which
can ZAP the front end of your radio.

I found this interesting:
http://www.geocities.com/CapeCanaveral/Launchpad/3652/amandx.html

 
 
 

STATIC BUILDUP ON ANTENNAS/Cure device

Post by Curtis M LaFo » Sun, 10 May 1998 04:00:00



> Sometimes you get a crackling sound on your antennas...particularly during snow
> storms (I'm told even worse in dust storms)...it may be static buildup which
> can ZAP the front end of your radio.

> I found this interesting:
> http://www.geocities.com/CapeCanaveral/Launchpad/3652/amandx.html


Wind blowing across a wire, especially if it is insulated will build up
a static charge. A grounded antenna, such as a delta loop will bleed it
off and makes a quiter receive antenna.
--

-------------------------------------------
Curtis .. N5HDQ .. http://wf.quik.com/n5hdq
I can't think of anything witty to say here.
Oh well, no one is perfect.

 
 
 

STATIC BUILDUP ON ANTENNAS/Cure device

Post by Lars Bergstr? » Tue, 12 May 1998 04:00:00


> Sometimes you get a crackling sound on your antennas...
> ...it may be static buildup which
> can ZAP the front end of your radio.

The principle of this mecanism can be demonstrated with the "Van der
Graf Generator", static build-up by mechanical friction on insulated
material. Long hair and a comb will also do.....

The static build-up is also observed on transport wires*** under
helicopters. The static can cause trouble at re-fueling stations!

Zapping of recivers front-end is indeed a potential problem. The static
buildup is caused by dry snow or dust blowing across insulated antenna
vires, and creating mechanical friction. Bleeding resistors or coils at
the input stage will de-electrify the antennas. Capacitive coupled
reciever input can cause static build-up until the breakdown voltage of
the capacitor. The result can be a zapped receiver input!

Bleeding resistors or a gas-filled spark arrestor is a good protector.

/Lars Bergstr?m

 
 
 

STATIC BUILDUP ON ANTENNAS/Cure device

Post by Dan Pi » Tue, 12 May 1998 04:00:00



>> Sometimes you get a crackling sound on your antennas...
>> ...it may be static buildup which
>> can ZAP the front end of your radio.

>The principle of this mecanism can be demonstrated with the "Van der
>Graf Generator", static build-up by mechanical friction on insulated
>material. Long hair and a comb will also do.....

>The static build-up is also observed on transport wires*** under
>helicopters. The static can cause trouble at re-fueling stations!

>Zapping of recivers front-end is indeed a potential problem. The static
>buildup is caused by dry snow or dust blowing across insulated antenna
>vires, and creating mechanical friction. Bleeding resistors or coils at
>the input stage will de-electrify the antennas. Capacitive coupled
>reciever input can cause static build-up until the breakdown voltage of
>the capacitor. The result can be a zapped receiver input!

>Bleeding resistors or a gas-filled spark arrestor is a good protector.

>/Lars Bergstr?m

Earlier receivers used a NE-2 neon bulb across the antenna input.  It may
also work on solid-state rigs.
 
 
 

STATIC BUILDUP ON ANTENNAS/Cure device

Post by Gdfthr7 » Tue, 12 May 1998 04:00:00

This is a static protection device for receivers taken from The DX-pedition
Handbook by Shawn Axelrod. Thought someone might want the info:
Materials required-

-Neon bulb (NE-2)
-10k resistor
-.01 uf cap., 500v or higher rating
-2 (two) SO-239 connectors (or appropraite connectors for your
  own rig), and
-Small solder lug

Construction-
Drill holes to mount the SO-239 ( or appropriate ) connectors on opposite ends
of the box, mount them and attach the solder lug to any mounting***you wish
on one of the connectors.
Solder one lead from the .01 uf cap. to the center conductor of one SO-239, and
the other lead to the center of the other SO-239.
Solder the 10k resistor across the solder lug and the connector that the lug's
attached to (solderlug-to-center conductor)...
Solder the NE-2 neon bulb to the same lug/center conductor as the resistor.
And of course, keep leads as short as possible!
Use:
The end plug WITHOUT the bulb/resistor connects to the receiver, the end WITH
the bulb/resistor connects to your antenna/feedline. Be certain to maintain
this orientation, otherwise the static protection will be minimal, and pretty
much useless!

Schematic:
ANT.  \|/
              |
              |                            .01 uf capacitor
              --------l-----l-------| (--------------------------------->> to
receiver
                         |      <
        (neon bulb)    >  (10k res.)
                         |      <
                         |-----l------------------------------------------>> to
receiver
                                 |
                                 |___
                                 (GND)
Hope this helps someone, I have built a few of them to put on my receivers and
have noticed that bulb pop a few times, and I'd MUCH rather replace a neon bulb
than throw away my rigs! :-)
Happy listening!
Mike in MO.

 
 
 

STATIC BUILDUP ON ANTENNAS/Cure device

Post by Gdfthr7 » Tue, 12 May 1998 04:00:00

Boy, that schematic looks awful on this group! :-) It looked better before I
sent it, I swear!
Oh well, it's a very simple circuit and should be easy even from the text
given.
Mike in MO.

 
 
 

STATIC BUILDUP ON ANTENNAS/Cure device

Post by Curtis M LaFo » Tue, 12 May 1998 04:00:00

N5HDQ offered:

A DC grounded antenna offers a path for static build-up to bleed off.
A delta loop and other types work, and are therefore a quieter and
better receive antenna.

If you don't have room enough to convert a wire dipole to a delta loop
an electrical 1/4 wave length of coax with one end shorted and the other
strapped across the antenna feed point will put an amount of inductive
reactance into the antenna which equals the ZO of the coax.

The antenna now is DC grounded but appears to be longer. Trim the ends
so it is back where you want it and you will have a quieter and shorter
antenna.

When going  the Delta Loop route I have found that using a 1/4 wave
matching stub works better than the 1/4 wave matching transformer
(I find that a lot of hams mistakenly call the transformer a stub)

There is a simple antenna program that I wrote available for download
at my site. It has a pic of both and a calculator to compute length and
placement of stub. There are the basic antennas and a few not not so
basic in the program. I have no idea who gets it so there will be no
follow up via e-mail. It's absolutely free.


> Boy, that schematic looks awful on this group! :-) It looked better before I
> sent it, I swear!
> Oh well, it's a very simple circuit and should be easy even from the text
> given.
> Mike in MO.

--

-------------------------------------------
Curtis .. N5HDQ .. http://wf.quik.com/n5hdq
I can't think of anything witty to say here.
Oh well, no one is perfect.