[time-nuts] ngTADD-1

Bob Camp lists at rtty.us
Tue Apr 23 06:43:27 EDT 2013


Hi

Like any design, the first question is - what's the goal?

If you have enough RF running around, then shielding is well worth looking at. How much of the cable is in "variable temperature" space? If it's all indoors / heated living space, even tempo may not be a big deal. All that said, I'd probably look at twinax. After you do all the get it in and get it out stuff, a balanced line often works best. It's a matter of baluns / transformers / amps and the coax structure. In a sense, a normal piece of coax is inherantly imbalanced (noise hits the shield).  If it's a single run, the connectors aren't going to be enough money to make it crazy. 

Bob

On Apr 22, 2013, at 11:18 PM, Kevin Rosenberg <kevin at rosenberg.net> wrote:

> On Apr 22, 2013, at 7:13 PM, Bob Camp <lists at rtty.us> wrote:
>> Ummmm, errrr. Even with all the mods, a 4501 is a fairly low resolution device. It's an amazing little box and I have several of them. Some (but not all) with the mods actually done correctly. 
> 
> Ummm, apologies for the errant posting that should have been a private message to N8UR.
> The 4501 was directed about a previous post to John.
> 
> The question for John about his new distribution amplifier was so that I could place my 
> RF and thermally-shielded 10811-60109 in the corner of my concrete basement. Then,
> run 100 ft of galvanically-isolated coax to my lab.
> 
> Now that's its public, do you have suggestions for the coax? I was thinking about LMR-240
> for its double-shielding and low tempco at 10 MHz.
> 
> Thanks,
> 
> Kevin
> 
> 
> 
> 
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