[RFI] just what everyone needs!

[Christopher Brown]

It is similar, though I have never seen specifics on what they use
material wise.


First time I saw it, it was refered to as "percap" or something similar.


It is just normal wire/cable with RF lossy insulation.


Not really that useful HAM wise as

It is $$$, speciality item and making RF lossy insulation that still
meets all the requires specs is not easy).


The loss per foot is pretty low until you get above VHF.


I have seen it used as power and low rate/analog signal hookup wire in
some cellular and microwave gear, as well as general purpose hookup wire
in large (build in place multi-rack) systems in high RF environments.


As I recall, loss was < 1db per 100ft above normal wire around HF, ~
10db per 100ft by 2m, and getting into the 5 - 10db per foot range by 2GHz.

I priced some 10ga once, ~ $10/ft in lots of 1000ft or less.


On 9/9/12 9:09 AM, qrv at kd4e.com wrote:
> Could the "resistive material" be powdered toroidal material?
> 
> Might one then twist it around a cable, or wrap it like a coil
> at a specific point, and at certain frequencies might it absorb
> RF?
> 
> Might the "22 gauge stranded (19/34), tinned conductor" be grounded
> at one end and serve as a drain?
> 
> Could the combo, wrapped around a coax line, be effective in blocking
> and draining ground-induced energy from lightning, snow-static, sand-
> static, and other low-level EMP?
> 
> Would a twisted pair of these be useful to carry a control voltage
> to or from a tower - impervious to ingress from near-field high-power
> RF?
> 
> Just speculating ... the physics is way beyond me.
> 
>> Believe it or not... its actually a mil spec item.  I did some searching and
>> it is mil-c-85485/5 which you can see at:
>> http://assistdocs.com/search/document_details.cfm?ident_number=34825&StartRo
>> w=54901&PaginatorPageNumber=1099&status_all=ON&search_method=BASIC
>>
>> It has a 3 layer insulation with some kind of absorber in the middle layer,
>> they don't say in the spec but I would assume its probably some kind of
>> resistive material.  They also say something about it only being effective
>> when used as a component in a shielded cable, so its probably not what you
>> want to run out and buy a bunch of to play around with.
>>
>>
>> David Robbins K1TTT
>> e-mail: mailto:k1ttt at arrl.net
>> web: http://wiki.k1ttt.net
>> AR-Cluster node: 145.69MHz or telnet://k1ttt.net
>>
>>
>> -----Original Message-----
>> From: Dave Cole [mailto:dave at nk7z.net]
>> Sent: Sunday, September 09, 2012 12:51
>> To: K1TTT
>> Cc: rfi at contesting.com
>> Subject: Re: [RFI] just what everyone needs!
>>
>> Oh Dear God!
>>
> 
>