[TenTec] humm

[Jim Brown K9YC]

On Thu, 26 Nov 2009 00:57:00 -0500, Richards  wrote:

>And, yet, TenTec told 
>me not to daisy chain the chassis grounds together 
>and their 963 power supply has no ground lug at all. 

The chassis of anything connected to the power line should be 
bonded internally to the green wire of the AC line cord, and I 
would bet that the Ten Tec p/s is built that way. Since this 
gear is used in a ham station with antennas, ADDITIONAL 
bonding is good practice for lightning safety. 

>AND... my station has no humm, or other adverse 
>audio issues. 

See the discussion of power-related buzz in my Ham Interfacing 
tutorial and the RFI tutorial. That is a different set of 
issues, but some of the solutions are in common (and never in 
conflict) with good practice for lightning protection. 

>So...   are these things all bonded to their respective
>chassis internally already... or is the daisy chain 
>ground lug theory something else... or what?  Other
>than some lightning protection on the antennas, I have
>no other ground other than the third prong on the power
>cords. 

The fly in the ointment is the INDUCTANCE of interconnecting 
copper. The longer the path, the greater the inductance, and 
thus the less effective it is at lightning protection. 

Power related buzz is different -- the key issue there IS 
resistance. 

>(I do pay attention to how I wire up the microphones...
>and have no problems with that... but I must confess
>I am STILL trying to understand all the nuances of that
>"pin 1 problem"  you audio engineers keep harping on.)

First, please understand that while "the pin 1 problem" was 
DISCOVERED by audio engineers, it is not ONLY an audio issue. 
It is a MAJOR cause of RFI to and from equipment. Study the 
material on my website to understand it. BTW -- it is now 
covered in Henry's Ott's latest book on EMC. 

Another BTW -- while the name "pin 1 problem" is confusing to 
non-audio engineers, the history of the world is that the guy 
who discovers something gets to name what he discovers. 
Unless, of course, someone else has a better press agent. :)

73,

Jim Brown K9YC