tom,
Just did a quick search for common mode chokes and saw this series from
Palomar engineers.
Not a reccommendation, just an example. Not as expensive as I'd thought.
http://palomar-engineers.com/antenna-products/1-1-balun-kits
tom Fowle WA6IVG
On Sun, Feb 21, 2016 at 06:25:15PM -0800, Tom Fowle wrote:
> tom,
> Remember this gizmo is just a hypothesis based on guess work?
>
> When you can get to putting common mode chokes on your feed lines, you have
> the choice of making them from turns of coax if you have extra length of
> cable or of putting on a bunch of appropriate ferrite beads over the
> feedline near the antenna. The beads are more expensive but if you don't
> have extra feedline maybe easier to accomplish. Suppliers of antenna
> accessories should be able to help you find the correct ferrites for your
> feedline.
>
> Nothing from my friend yet. I'm not mentioning his name with out his sayso
> since he's not a ham.
>
> good luck
> Tom Fowle WA6IVG
>
> On Sun, Feb 21, 2016 at 12:09:44PM -0500, Tom Behler wrote:
> > Tom:
> >
> > Thanks for the clarification. ... It helps a lot.
> >
> > I don't know if I'll get to it today, but this is certainly worth a try.
> >
> > If you get any thoughts from your engineer friend, please pass them along.
> >
> > If you want to write to me privately, my address is:
> >
> > [log in to unmask]
> >
> >
> > Tom Behler: KB8TYJ
> >
> >
> > -----Original Message-----
> > From: For blind ham radio operators [mailto:[log in to unmask]]
> > On Behalf Of Tom Fowle
> > Sent: Saturday, February 20, 2016 11:52 PM
> > To: [log in to unmask]
> > Subject: Re: Next RFI Update, and question for Tom: WA6IVG
> >
> > tom,
> > My thought is this thing would replace the ground wire from the common shack
> > point or the outside ground point on your window panel, going to the ground
> > rod.
> >
> > If I were going to mess with this, and it is purely hypothesis, I'd make the
> > common mode chokes maybe 8 turns on a 6 or 8 inch diameter form.
> >
> > At the ground rod end, I'd connect the center and shield together and to the
> > ground rod.
> > At the top, just the center conductor to the ground on your window panel.
> >
> > Again this is perhaps nonsense. purely hypothetical, my vague theory is the
> > chokes would keep common mode current off the outside of this new type of
> > "shielded ground"
> >
> >
> > I'd much rather see you put common mode chokes in the feeds near your actual
> > antennas, but understand the weather makes that difficult.
> >
> > Gaads Tom, you might just have to turn off the "boots" <HORRORS!>
> >
> > I've written to my engineer friend discribing the aforementioned shielded
> > ground, we'll see if he has anyting to say.
> > Tom Fowle WA6IVG
> >
> >
> > On Sat, Feb 20, 2016 at 11:30:06PM -0500, Tom Behler wrote:
> > > This is a multipart message in MIME format.
> > >
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> > >
> > > Hi, all.
> > >
> > >
> > >
> > > I thoroughly checked all of my coax jumpers in the shack for
> > > continuity, and all looked good. But, RFI issues still occurred.
> > >
> > >
> > >
> > > I then found a few small RG9913 jumpers I had lying around, and
> > > actually had two snap-on RF chokes that could accommodate that size of
> > > coax. Put one at the output of the TS590, and the other between the
> > > output of my MFJ998 auto-tuner, and the common connector on my
> > > six-position Alpha Delta antenna switch. Still no joy.
> > >
> > >
> > >
> > > Now, I have a question for Tom: (WA6IVG):
> > >
> > >
> > >
> > > In your last post with the subject of "shielded ground", you posed a
> > > possible solution for an in-the-shack common ground. You said:
> > >
> > >
> > >
> > > How about a piece of coax as ground wire with center conductors used
> > > as the actual ground.
> > >
> > > Now take the coax and wind a common mode choke in it at each end, but
> > > do nothing with the shield at the top and ground the shield at the
> > bottom."
> > >
> > >
> > >
> > > I'm a bit confused: where exactly would you connect both ends of this
> > > new grounding cable made out of coax? Obviously, one end would go to
> > > the common ground connection on my feed-through panel, but I'm not
> > > sure where the other end would go. Also, how would you ground the
> > > shield at the other end of the cable? And, what would you recommend
> > > for the size of the common mode chokes on each end?
> > >
> > >
> > >
> > > I have some extra coax here that I'd be willing to try this with
> > > sometime tomorrow.
> > >
> > >
> > >
> > > Tom Behler: KB8TYJ
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
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> > > link=3Dblue = vlink=3Dpurple><div class=3DWordSection1><p
> > > class=3DMsoNormal>Hi, = all.<o:p></o:p></p><p
> > > class=3DMsoNormal><o:p> </o:p></p><p = class=3DMsoNormal>I
> > > thoroughly checked all of my coax jumpers in the = shack for
> > > continuity, and all looked good. But, RFI issues still =
> > > occurred.<o:p></o:p></p><p class=3DMsoNormal><o:p> </o:p></p><p =
> > > class=3DMsoNormal>I then found a few small RG9913 jumpers I had lying
> > > = around, and actually had two snap-on RF chokes that could
> > > accommodate = that size of coax. Put one at the output of the
> > > TS590, and the = other between the output of my MFJ998
> > > auto-tuner, and the common = connector on my six-position Alpha Delta
> > > antenna switch. Still no = joy.<o:p></o:p></p><p
> > > class=3DMsoNormal><o:p> </o:p></p><p = class=3DMsoNormal>Now, I
> > > have a question for Tom: = (WA6IVG):<o:p></o:p></p><p
> > > class=3DMsoNormal><o:p> </o:p></p><p = class=3DMsoNormal>In your
> > > last post with the subject of “shielded = ground”, you
> > > posed a possible solution for an in-the-shack common = ground.
> > > You said:<o:p></o:p></p><p = class=3DMsoNormal><o:p> </o:p></p><p
> > > class=3DMsoPlainText>How about = a piece of coax as ground wire with
> > > center conductors used as the actual = ground. <o:p></o:p></p><p
> > > class=3DMsoPlainText>Now take the coax and = wind a common mode choke
> > > in it at each end, but do nothing with the = shield at the top and
> > > ground the shield at the = bottom.”<o:p></o:p></p><p =
> > > class=3DMsoPlainText><o:p> </o:p></p><p =
> > > class=3DMsoPlainText>I’m a bit confused: where exactly
> > > would = you connect both ends of this new grounding cable made out of
> > > = coax? Obviously, one end would go to the common ground
> > > connection = on my feed-through panel, but I’m not sure where
> > > the other end = would go. Also, how would you ground the shield
> > > at the other end = of the cable? And, what would you recommend
> > > for the size of the = common mode chokes on each end?<o:p></o:p></p><p
> > > = class=3DMsoPlainText><o:p> </o:p></p><p class=3DMsoPlainText>I
> > > have = some extra coax here that I’d be willing to try this with
> > > sometime = tomorrow.<o:p></o:p></p><p
> > > class=3DMsoPlainText><o:p> </o:p></p><p =
> > > class=3DMsoPlainText>Tom Behler: KB8TYJ<o:p></o:p></p><p =
> > > class=3DMsoPlainText><o:p> </o:p></p><p =
> > > class=3DMsoPlainText><o:p> </o:p></p><p =
> > > class=3DMsoNormal><o:p> </o:p></p></div></body></html>
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