[time-nuts] Query about insulated coax panel connectors?

[Bob kb8tq]

Hi

Mini-circuits will sell you the transformers already in a box. Needless to say,
they do charge a bit for that. Occasionally, you can find them on eBay for
a more rational price. 

If you are going the DIY route, incorporating a couple of common mode
chokes on both sides of the transformer is probably a good idea. Once 
you get rid of 60Hz, the next problem is all the crud your cell phone or 
WiFi device is spouting …..

Bob

> On Oct 24, 2020, at 6:35 PM, paul swed <paulswedb at gmail.com> wrote:
> 
> Jim
> A couple of other suggestions.
> A 1:1 Mini circuits transformer external to the unit They are quite small
> and offer electrical isolation also. Use a small pomona box etc.
> Another possibility is the typical RCA phono jack and plug. They come in
> insulated models. Understanding its not 50 ohms but the discontinuity
> length is pretty short.
> Good luck and what you are doing does work.
> I actually use the small 100 bT ethernet transformers from China. DIP size
> two to a 14 pin package. Seriously does the job something like 500 Vac
> isolation and no ground loops. They are inexpensive or at least were. 10 X
> $2 or something silly and had been free shipping. Who knows these days.
> Regards
> Paul
> WB8TSL
> 
> 
> On Sat, Oct 24, 2020 at 4:44 PM AC0XU (Jim) <James.Schatzman at ac0xu.com>
> wrote:
> 
>> Time-nuts:
>> 
>> Having recently run into major ground loop noise issues, I have begun
>> reworking some of my homemade pieces of equipment using insulated coax
>> connectors. My goal is to have one ground connection only in the cases, and
>> that is at the power entry point, either a power cord or the outer terminal
>> of a DIN. I am also installing isolation baluns on inputs and/or outputs.
>> 
>> Insulated BNCs are readily available. Others not so. In some cases, there
>> is not room to install an insulated BNC. I am not finding any insulated
>> SMA, SMC,  SSMA, or SSMC despite googling and searching catalogs.
>> 
>> Does anyone know of a source for insulated small threaded coax panel
>> connectors?
>> 
>> Another option would be a compact insulating bushing that an SMA panel
>> connector, for example, could be mounted in. I am not finding anything like
>> that either...  In fact the ideal solution would be an insulated SMA with
>> an integrated 1:1 balun.
>> 
>> And I am not thinking about using plastic cases - that would introduce a
>> whole other set of problems. I think about my lab area at work where a
>> bundle of dozens of gigabit ethernet cables run through the roof directly
>> over the lab bench - the ambient noise level is quite high.
>> 
>> Suggestions???
>> 
>> The only idea I have some up with is to design something myself, possibly
>> 3-D printed...  Any suggestions about how to get started on something like
>> that?
>> 
>> Thanks in advance-
>> Jim
>> 
>> 
>> 
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