Topband: Commond mode choke for Beverage

[shristov]

With 5943003801 and RG58, closely fill-in a single layer,
leaving 10-15 mm on the outside perimeter unused.
That should be ~16 turns, giving you impedance near 4000 Ohm.

Such a choke should be placed close to all points where
the current on the outer surface of the coax shield
can pass to the coax inside space.

This usually means near RX connector, and at the Beverage end of the feeding coax.
If the feed line is very long, then a few chokes may be inserted here and there.

But take care to make all coax joints completely shielded,
otherwise chokes may be bypassed.


73,

Sinisa  YT1NT,  VE3EA



----- Originalna poruka -----
Pošiljalac: Filipe Lopes <ct1ilt at gmail.com>
Datum: Ponedeljak, Oktobar 12, 2015 15:52
Tema: Re: Topband: Commond mode choke for Beverage
Primalac: JC <n4is at comcast.net>
Cc: topBand <topband at contesting.com>

> Hello JC,
> 
> Thanks for your answer.
> 
> I just ordered a few 2631803802 and 5943003801 from mouser.
> 
> With these ferrites I ask the same question, should I put the 
> choke close
> to the 9:1 Balun or near the switching box and how many turns? 
> some bevs
> have the feed point at +- 60m away from the switching box.
> 
> 
> 73's Filipe Lopes
> CT1ILT - CR6K
> F4VPX - TM3M
> 
> 2015-10-12 15:40 GMT+02:00 JC <n4is at comcast.net>:
> 
> > Hi Filipe
> >
> > Zero , you should use material #31  or #77 , The core you 
> have is not good
> > for low bands.
> >
> > JC
> > N4IS
> > -----Original Message-----
> > From: Topband [mailto:topband-bounces at contesting.com] On 
> Behalf Of Filipe
> > Lopes
> > Sent: Monday, October 12, 2015 8:46 AM
> > To: topBand <topband at contesting.com>
> > Subject: Topband: Commond mode choke for Beverage
> >
> > Hi guys,
> >
> > I am about to add a common mode choke to isolate the antenna 
> from its
> > feedline to each of my beverages and I only have FT240-61 
> ferrites. My
> > question is how many turns should I do on the ferrite using 
> RG58 (all my
> > bevs are fed with RG58). Also should I put the choke near the 
> 9:1 balun or
> > near my bev switching box?
> >
> > Thanks in advance.
> >
> > 73's Filipe Lopes
> > CT1ILT - CR6K
> > F4VPX - TM3M
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> >
> >
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