I usually avoid public testimonials, but in this thread, I choose to
make an exception.
For those who have interest in this discussion, I notice that Jim Brown
has been a bit bashful in stating his credentials. Jim has extensive
experience with EMC and RFI in both ham radio and pro-audio systems.
Take a look at http://www.audiosystemsgroup.com/bio-jb.htm for his
professional pro-audio profile, or for something more ham related, look
at http://www.audiosystemsgroup.com/K9YC/k9yc-bio.htm.
For those interested in his technical publications, they can be seen at
http://audiosystemsgroup.com/K9YC.htm - it is an extensive library.
I consider Jim's work to represent examples of good engineering practice
in the fields of Pro-Audio, EMC and RFI.
Keep up the good work Jim - you and your research are a great asset to
the amateur radio community.
73,
Don W3FPR
Jim Brown wrote:
On Sun, 8 Jun 2008 20:33:15 -0400, Joe Subich, W4TV wrote:
I'm aware that a short jumper is "wrong" from the purist point
of view. However, it is much better than mic return that is
held above ground by an RF choke! Most of the rigs I've seen
have relatively good grounding for the "PTT ground" - the jumper
is 1 cm or less or the circuit board layout includes the "PTT
Ground" pin in a wide (large) ground plane.
Fortunately, most amateur equipment is not operated in strong
(multi hundred KW ERP) UHF fields.
This is NOT purist. The cell phone interference being discussed in
another thread could easily be the result of a jumper that short. It is
in those mics! The field is determined by inverse square law. A 2W
radio (cell phone) puts a pretty strong field at 6-12 inches. Back in
Chicago, I ran 160M and 80 on a long wire that ended at the transmitter.
With only 13W (K2 barefoot) I could lock up the keying loop between the
computer and the radio.
Which article? I used many of the Neuman and AKG mics 30 years ago
The AES paper on RFI in condenser mics has the greatest detail. I've
summarized it and used it tutorially in other publications.
73,
Jim Brown K9YC
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