Mribob,
how come my bedroom sat system has no ground hum;
More than likely the associated equipment is two wire cord and plug. Is that correct?
I switched out my Meridian 861 processor for a Marantz 7005 processor;(no hum before with same sat box and connections)
Marantz uses a two wire cord and plug. Does the Meridian 861 processor use a three wire cord and plug?
I had electrician come out to house and attach dedicated ground wire to a grounded piece of metal on house; ie; electrical conduit.
Does not meet NEC code......
Good chance what you have with the metal conduit is a poor lightning grounding conductor at best. Every fitting, connectors and couplings, could be adding resistance to the length of the conduit run.
NEC code says the cable grounding block shall be bonded, connected, to the main grounding electrode system of the main electrical service by means of a ground wire. NEC code is bare minimum safety standards.....
How far is the SAT cable grounding block from the main electrical service panel?
For a test, test only, disconnect the existing pipe ground wire from the SAT cable ground block. Check for hum and post back.
Note:
The ground block must be earth grounded for lightning protection. For the test you will not cause any harm....