[TenTec] RFI into Orion II

[Gary J FollettDukes HiFi]

I agree with your position about grounds versus shields.

Sadly, many audio manufacturers do not follow this design rule. I offer as evidence some very high end cables from a very high end record player tonearm manufacturer. The audio interconnect cable shields are only tied to ground on one end (the arm end). They are not even brought out of the cable insulation on the other end. Instead, a third wire down the middle of the cable pair carries the “ground” connection from the arm to the preamplifier. Guess what, I have hum.

Different area of interest, same problem…

Gary



> On Feb 21, 2016, at 8:48 PM, Jim Brown <k9yc at audiosystemsgroup.com> wrote:
> 
> Let's get our words straight. First, a cable shield is a SHIELD first, and a circuit conductor second. It is NOT a "ground." For a shield to WORK, it MUST be connected directly to the shielding enclosure at both ends. That is a fundamental principle of shielding -- it must be continuous. Sadly, virtually all mfrs of ham gear fail to understand this, and tell us to do things that are simply WRONG.
> 
> A cable shield that is NOT connected directly to the chassis at the point of entry is a CAUSE of hum, buzz, and RFI. Failure to follow that fundamental principle is known in the audio world as "the Pin One Problem," and was first exposed by Neil Muncy, ex-W3WJE (SK), in 1994.
> 
> There are several tutorials on my website about this, and I urge all to study them.
> k9yc.com/publish.htm
> 
> I will NOT waste my time by repeating that tutorial work here for those who are too lazy to read what I've already taken the time to write. :)
> 
> 73, Jim K9YC
> 
> On Sun,2/21/2016 3:37 PM, Sergio Escudero wrote:
>> Hi to all, the problem is the ground with the microphone (must) be separated from the chassis ground, separate the mic capsule ground from the shield and radio chassis see figure 2.4 of mic connection  me and a local friend we have wire several mic to the Orion2 , this will fix the RFI problem W4ESA
> 
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