[HomeBrew] Help with RF chokes

Tue, 15 Jul 2003 08:22:09 -0500

Owning a high sierra I have never attempted to reduce the noise that occurs 
when changing the loading (operating the screwdriver motor) when changing 
bands or frequency.  The motor noise acts as a noise generator and peaks on 
my rx audio when I get to the point where I have my rx/tx frequency set.

73, Jim, wd4air

>From: "JimClark" <[email protected]>
>To: <[email protected]>
>Subject: RE: [HomeBrew] Help with RF chokes
>Date: Mon, 14 Jul 2003 22:17:57 -0500
>
>** Please do NOT cross-post messages to multiple mailing lists on the "To:" 
>or "CC:" line of the e-mail message. **
>
>I built mine from plans supplied by DK Johnson W6AAQ and I put a .1 disk
>cap across the motor leads and two more, one on each pole to gnd. I
>stole several of those ferrite cylinders from some old keyboard leads
>and put them on the power cable close to the outside of the antenna
>base. I can just barely hear the motor and I now don't get bit when
>keying up on 15 mtrs.
>
>Hope this helps your situation.
>
>Jim, N5QL
>
>-----Original Message-----
>From: [email protected]
>[mailto:[email protected]] On Behalf Of Brian Carling
>Sent: Monday, July 14, 2003 6:31 PM
>To: [email protected]
>Subject: Re: [HomeBrew] Help with RF chokes
>
>** Please do NOT cross-post messages to multiple mailing lists on the
>"To:" or "CC:" line of the e-mail message. **
>
>Doesn't Radio Shack sell a brute-force RF filter for DC leads in a car
>that would
>work for that? I think they used to have them a few years ago at least.
>
>On 8 Jul 2003 at 14:06, [email protected] wrote:
>
> > ** Please do NOT cross-post messages to multiple mailing lists on the
> > "To:" or "CC:" line of the e-mail message. **
> >
> > Hi Guys;
> >
> > I need help again. I want to put RF chokes in the motor leads to my
> > screwdriver antenna. I don't know what inductance is good for the HF
> > band. I don't know if any are available commercially. I would like to
> > wind my own if I knew the parameters. I measure 800 ma running and in
> > excess of 10 Amperes when stalling at the end. I would not normally
> > allow it to stall but I wouldn't want to lose a choke if it did. I was
> > thinking about a bifiler winding on a ferrite rod (like a filament
> > choke) but don't know the core material or number of turns. Any help
> > would be appreciated. Thank you.
> >
> > Ed Richards K6UUZ
> >
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