[600MRG] Coax shielding effectiveness

[david vanhorn]

I knew fsj1-50 would be good but I haven't found data from anyone at these
low frequencies. Any pointers would help.

On Mon, Dec 9, 2019, 12:14 PM Gedas <w8bya at mchsi.com> wrote:

> Hi Dave. Funny you should ask. I am right in the middle of making a video
> where I test about 10 different (and common) coaxial cables specifically
> for their SE. The project is on and off as I just have too many pokers in
> the fire right now.
>
> It is not as simple as one may think to measure the SE accurately esp if
> the cable is of high quality and has a high SE. If I were still employed
> and had access to my old lab and shielded enclosures and able to generate &
> measure known RF fields from DC to daylight it would be a much, much easier
> task. Having to do it in my basement lab makes it a much more challenging
> project. In the end I chose to arrive at the SE by measuring the cross-talk
> between two identical coax cables.
>
> My methodology is to lay two identical cables of equal length next to each
> other on a plywood table. Both far ends of the coax cables are terminated
> in 50 ohm loads. One cable is driven with a tracking generator (then
> broadband power amplifier) while the other coax fed into the input of my
> spectrum analyzer. The amount of cross-talk between the two cables can then
> be used to directly see what the SE was. It gets hairy if the cables have a
> high SE as the SA has a limited sensitivity (NF) and I can only generate
> several watts of broadband RF from DC to about 1 GHz.
>
> Until that video is done you will have to go by OEM data. FSJ1-50 will
> have an extremely high SE (well over 100 dB). If you need some help looking
> up the exact OEM data just hollar. 73
>
> Gedas, W8BYA
>
> Gallery at http://w8bya.com
> Light travels faster than sound....
> This is why some people appear bright until you hear them speak.
>
> On 12/9/2019 1:37 PM, david vanhorn wrote:
>
> I've been searching around without much success.
> I'm trying to find data sheets or good measurements of shielding
> effectiveness of the various coax types, including FSJ1-50 for this band.
> I'm not seeing anything talking much below 100MHz.
>
> Can someone point me in the right direction?
>
> --
> K1FZY (WA4TPW) SK  9/29/37-4/13/15
>
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