[time-nuts] Re: Query about List and about 10 MHz Distro

[Bob kb8tq]

Hi

With *any* cable setup, proper termination is vital. An improperly terminated 
balanced line can be just as bad as a poorly terminated coax. Things like
common mode chokes are part of a *lot* of setups. 

What gets messy is that a lot of gear does not properly terminate the cable. 
It’s high-z so you can run a bunch of them with Tee connectors or some other
strange approach. >20 db of return loss is *not* what most cables get terminated
in. 

It doesn’t take a lot of coax to get a quarter wave at 10 MHz. Anything nearly
that long is going to be a radiator if you let it. 

This all gets a bit insane if you have multiple 10 MHz sources (like devices 
you are testing). Close in phase noise and ADEV both can get really strange 
as a result.

Lots of issues ….

Bob



> On Aug 29, 2021, at 10:44 AM, Dana Whitlow <k8yumdoober at gmail.com> wrote:
> 
> Andy,
> 
> Balanced twisted pair may be helpful, but only if adequate precautions are
> taken to
> avoid creation of common mode *currents *on the line*.*
> 
> Dana
> 
> 
> On Sun, Aug 29, 2021 at 9:34 AM Andy Talbot <andy.g4jnt at gmail.com> wrote:
> 
>> Hence my observation that balanced twisted pair might be a better solution
>> than coax for 10MHz distribution
>> Removes all possibility of ground loops
>> 
>> Andy
>> www.g4jnt.com
>> 
>> 
>> 
>> On Sun, 29 Aug 2021 at 15:22, Dana Whitlow <k8yumdoober at gmail.com> wrote:
>> 
>>> I believe that a significant problem in my case was not leakage through
>> the shield,
>>> but
>>> rather common-mode currents on the cable.  My experiences were with RG-6
>> style
>>> cable,
>>> namely a cable that mostly went around the outside of the house for TV
>>> distribution.
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at lists.febo.com -- To unsubscribe send
>> an email to time-nuts-leave at lists.febo.com
>> To unsubscribe, go to and follow the instructions there.
>> 
> _______________________________________________
> time-nuts mailing list -- time-nuts at lists.febo.com -- To unsubscribe send an email to time-nuts-leave at lists.febo.com
> To unsubscribe, go to and follow the instructions there.