On Wed, 23 Jul 2008 19:40:06 -0400, Bill Mellema wrote:
>I now have a new OMNI VII which I really like ..however I noticed
>again that walking across my carpeted office and touching the mike
>connector caused the receiver to quit. If I recycle the power it is
>fine again. I had this problem with another OMNI VII I owned and
>never could get it straightened out. I am running a ASTRON 55 AMP
>power supply with the chassis ground going back to the OMNIVII's
>chassis ground (I did this after the ESD problem was first noticed).
>I have since measured the resistance from the OMNI VII's chassis
>ground and the mike connector and the 1/4 inch CW and Headphone
>jacks. They are all above ground which I think is the problem. Heck
>you can ground the radio but what does it do if the front panel jacks
>aren't grounded?
I don't know anything specific about this particular radio, but you're
right, it is EXTREMELY BAD DESIGN for a cable shield to not be
connected directly to the chassis. What you describe is known in the
world of pro audio as "a pin 1 problem" (because pin 1 of XL connectors
is the cable shield), and is well known as a MAJOR cause of hum, buzz,
and RFI. The Omni V is FULL of pin 1 problems. So is my FT1000MP.
Indeed, MOST ham gear has a pin 1 problem at most of its audio and
control inputs and outputs. Don't know about later Ten Tec rigs.
Another question, however. Is your rig grounded? It should be -- in
fact, it should be grounded both to the power system and any station
ground should have a good, low impedance bond to the power system
ground. This MIGHT help, but if you do, indeed, have a pin 1 problem,
you really need to fix that first.
There's a lot of tutorial material on my website that discusses the pin
1 problem in detail. http://audiosystemsgroup.com/publish
73,
Jim Brown K9YC
_______________________________________________
TenTec mailing list
TenTec@contesting.com
http://lists.contesting.com/mailman/listinfo/tentec
|