Topband: Palomar R-X Noise Bridge

[ZR]

> 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!


Oh, the fun we had almost living in a screen room in order to get a product 
past those inspectors!! The effect of shielding and ferrites has been 
permanently imprinted on my brain. I sometimes have to laugh when reading 
that some consider a sleeve balun/choke to be a recent invention!

Maxwell sort of stumbled on it in later years with those tiny beads that 
seriously overheated with most amps. We "started" with the type that fit 
over RG-213 and went from there to custom made, the big donuts, and sheet 
products from pioneers such as Arnold.

Carl
KM1H

>
>> 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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