Topband: Palomar R-X Noise Bridge

[Charlie Cunningham]

Hi, Jim

 

Well, Maxwell's "W2DU" balu ns are ferrite sleeve baluns and you can get
those that go down to 160m. It's a matter of choosine the right ferrite for
the frequenc;y range of interest, and using enough ferrite to build p the
common-mode impedance!

 

73,

Charlie, K4OTV

 

 

From: James Rodenkirch [mailto:rodenkirch_llc at msn.com] 
Sent: Saturday, February 15, 2014 11:45 AM
To: Charlie Cunningham; 'Carl'; Top Band Contesting
Subject: RE: Topband: Palomar R-X Noise Bridge

 

Carl:  I've read, at several places, that sleeve baluns are effective at VHF
and above but not at HF frequencies..thoughts??

 

72/73, Jim Rodenkirch --- former Tempest inspector for the U.S.
Navy..ahhhhh...Tempest comcerns - the good 'ol days  hi Hi!

 

> From: charlie-cunningham at nc.rr.com
> To: km1h at jeremy.mv.com; topband at contesting.com
> Date: Sat, 15 Feb 2014 11:39:14 -0500
> Subject: Re: Topband: Palomar R-X Noise Bridge
> 
> I'm a great believer in ferrite sleeve baluns, Carl! That's all that I
use,
> and with a little work you can even connect two of them for 4:1 nalance.
> 
> 73,
> Charlie, K4OTV
> 
> -----Original Message-----
> From: Carl [mailto:km1h at jeremy.mv.com] 
> Sent: Saturday, February 15, 2014 11:05 AM
> To: Charlie Cunningham; 'TopBand'
> Subject: Re: Topband: Palomar R-X Noise Bridge
> 
> The lowest loss cable I have here is 75 Ohm 1" General Cable Fused Disc;
its
> 
> under a differnt name these days. Mostly air with poly discs and used for 
> the 200' runs for 10M, 2M, and 222 MHz.
> 
> For the 160/80 inverted vee it is 450' of regular foamed 3/4" 75 Ohm CATV 
> hardline with a RG-11 jumper and plenty of ferrite to the feed point. Ive 
> been using ferrite sleeve baluns since the mid 70's; I was introduced to 
> them by the company I worked for who was building equipment for the joint 
> CIA/DOD Tempest program.
> 
> Carl
> KM1H
> 
> 
> ----- Original Message ----- 
> From: "Charlie Cunningham" <charlie-cunningham at nc.rr.com>
> To: <jim at audiosystemsgroup.com>; "'TopBand'" <topband at contesting.com>
> Sent: Friday, February 14, 2014 10:00 PM
> Subject: Re: Topband: Palomar R-X Noise Bridge
> 
> 
> > All generally true, I expect, but I also believe that dielectric
constant
> > and dielectric losses also figure in and the lowest loss lines would be
> > filled with air, dry nitrogen or evacuated. I expect those would likely
be
> > the lowest loss AND highest velocity factor cases.
> >
> > 73,
> > Charlie, K4OTV
> >
> > -----Original Message-----
> > From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of Jim 
> > Brown
> > Sent: Friday, February 14, 2014 9:42 PM
> > To: 'TopBand'
> > Subject: Re: Topband: Palomar R-X Noise Bridge
> >
> > On 2/14/2014 2:17 PM, Carl wrote:
> >> Isnt that what "lowest loss" means? At least that was my intention.
> >
> > I must not have written clearly enough. I was not questioning the low
> > loss, only that the high Vf was the way to get it.
> >
> > You DO get the low loss by going to larger coax, (like the 7/8-in hard
> > line), but it's the fact that it's LARGER and has lower RF resistance,
> > NOT the higher Vf.
> >
> > Think of it this way -- The higher Vf cable has less attenuation per ft
> > because the higher Vf allows the center conductor to be larger.
> > But a stub made with foam coax with Vf = 0.84 must be 27% longer than
> > one with with a solid dielectric and Vf =.66. If those coaxes are the
> > same diameter and of comparable quality, the stub attenuation and Q will
> > be nearly the same.
> >
> > 73, Jim K9YC
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> > 
> 
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