Topband
[Top] [All Lists]

Re: Topband: Palomar R-X Noise Bridge

To: "'Carl'" <km1h@jeremy.mv.com>, "'TopBand'" <topband@contesting.com>
Subject: Re: Topband: Palomar R-X Noise Bridge
From: "Charlie Cunningham" <charlie-cunningham@nc.rr.com>
Date: Sat, 15 Feb 2014 11:39:14 -0500
List-post: <topband@contesting.com">mailto:topband@contesting.com>
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@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@nc.rr.com>
To: <jim@audiosystemsgroup.com>; "'TopBand'" <topband@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@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
> _________________
> Topband Reflector Archives - http://www.contesting.com/_topband
>
> _________________
> Topband Reflector Archives - http://www.contesting.com/_topband
>
>
> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 2014.0.4259 / Virus Database: 3705/7095 - Release Date: 02/15/14
> 

_________________
Topband Reflector Archives - http://www.contesting.com/_topband

<Prev in Thread] Current Thread [Next in Thread>