[time-nuts] Remote GPS Oscillator Steering

[Christopher Brown]

I happen to have a less than ideal ham shack/lab and antenna setup.


The shack/lab is second floor in the rear.

The main antenna is an inverted L 30ft straight back from the shack.


There are about 50 pounds of type 31 ferrite in the house suppressing
_everything_ to the point that I cannot tell whether house power is on
or off on any band.



If I swap out a single 4ft jumper in my 10Mhz dist system with generic
rg58 it is easily detectable.  Not strong enough to swamp wwv during
peak hours, but as strong or stronger about 12 hours of the day.


I got tired of wasting time tracking down issues.  Times Microwave
LMR-240 is ideal for 10Mhz dist and very well shielded.  All my
timing/small signal stuff is LMR-240.  All of the antenna runs and large
signal stuff is LMR-400 or LMR400-UF.



When I originally temped up my 10Mhz dist system (tbolt feeding 5087
feeding 10 HP devices) using rg58 I had on hand...  The 11 runs (about
70 feet total) radiated enough match or exceed wwv receive strength 24/7

Now, 500 feet away, diff story but it does not take much leakage with
30ft seperation.  With LMR-240...  I have to use a pickup antenna in the
middle of my lab to detect 10Mhz leakage and only then when the band is
closed and background noise at a minimum.

Even good RG58 is 78% shield coverage or less, with odd/generic stuff
with < 50% coverage floating around.  240 is multi-layer 100%
coverage...rated at > 90db shielding.

On 4/18/13 8:23 AM, Hal Murray wrote:
> 
> iain at g7iii.net said:
>> Oh I know it can handle it, I was trying to avoid a nice 10MHz signal on an
>> unshielded conductor smack on the Amateur Radio 30m band :) It's more RF
>> here than Time/Frequency, and if I can avoid clashes, so much the better...
> 
> Has anybody measured the radiation from various types of coax and/or twisted 
> pairs?
> 
> It would be interesting to see how they compare and/or how they compare to 
> things like unterminated unused outputs or emissions from gear with the lid 
> off and things like that.
> 
> 
>