Hum/buzz Noise In My Radio

[GnG8d]

Correct. I have several ground rods at the tower base and all along the perimeter ground which is tied to my electrical service entrance. From this point I have ONE piece of heavy copper cable running into the shack where I have a ground buss with ground leads going to various pieces of gear. I'm not sure exactly how 222dbfl has his configured however I just wanted to mention that multiple ground points does not necessarily mean ground loops. A lot of people think that just because there is more than one ground rod than there will be ground loops present. Not so as long as they are all connected together at one point and not multiple points.

I edited, I'm with you I think. But that's a lot different than driving ground rods and giving the secondary of your service transformer many grounds to choose from. That creates the possibility of potential between grounds and a lighting strike nightmare.

 

[Captain Kilowatt]

If I'm understanding, all of your grounds are external of your house wiring and are then bonded to the service ground? You don't have equipment separately grounded to 6 or 7 different ground points.

EDIT___
You have 3 ground rods at the tower base to try and dissipate as much of a hit that you can there. What doesn't go to ground goes to the house via a ground cable and coax shield but doesn't enter the house, it is then diverted to the service ground. I'll buy that.

Not quite. What this does is make all grounds at the same electrical potential. Believe it or not not all grounds are at zero volts especially during a lightning strike. Damage occurs when current flows from one ground to another. Such is the case when the ground at the base of a tower raises to hundreds or even thousands of volts for a fraction of a second until the ground can dissipate the energy while a ground located a distance away is still at a lower voltage. think of it as a wave traveling thru the ground. It travels slower thru the ground than in a good conductor like a heavy copper strap or cable. When all grounds are connected together then all ground points rise and fall in electrical potential (voltage) together at the same time and if they do this then no current can flow as there is no voltage difference between them. It is more of an exercise in keeping voltages the same until the energy can be dissipated in the ground and not so much in dissipating or diverting energy that "is left" after the first ground rods.

 

[GnG8d]

I'm with you, and maybe that's what 222dbfl is doing, but it sounded like he was grounding different parts of his house to different ground points which can be disastrous.

 

[Captain Kilowatt]

Agreed and like I said I was not sure how he has things set up.

 

[unit_399]

There is a main ground cable running from the tower towards the house where it encircles the entire house. there are multiple ground rods along the length.

CK. -
Can you explain the benefits of encircling the house with the main ground line rather than running it directly to the electrical service ground. I ask this because the station I worked at used the same setup at the antenna site where the main tower ground cable encircled the building that housed the transmitter. I never understood why this was done. Thanks and 73s.

- 399

 

[222DBFL]

Yep several ground rods all connected together to a single point ground. Sorry if I didn't mention that but I do know how to ground properly. I am not the greatest when it comes to this stuff but I know a little. Thanks for the help explaining capt.

 

[KennyD]

I replaced the processor board today with negative results. I also soldered the board to chassis screws to ground. Could the RF amplifier transistor (Q66) cause this noise in my audio? I noticed It gets very hot so I am wondering if its shorted or burned out. I noticed today that the noise gets louder with the RF power turned all the way down to 1 watt. It is an 2SB827.

 

[GnG8d]

I also soldered the board to chassis screws to ground. Could the RF amplifier transistor (Q66) cause this noise in my audio?

I would not DC ground the board and chassis, they are AC coupled. If Q66 is a final transustor, no I can't see that being the source of the hum.

 

[Captain Kilowatt]

CK. -
Can you explain the benefits of encircling the house with the main ground line rather than running it directly to the electrical service ground. I ask this because the station I worked at used the same setup at the antenna site where the main tower ground cable encircled the building that housed the transmitter. I never understood why this was done. Thanks and 73s.

- 399

Sorry.....I meant to reply sooner but forgot about it. Here is a link that explains good grounding techniques.

http://www.worldwidedx.com/threads/good-info-about-grounding.136571/

Basically surrounding the structure allows you to connect to a ground point on fhe opposite side without passing a ground and hence a lightning path thru the structure and by creating a perimeter ground you have a much better area to dissipate strike energy due to multiple ground rod placement and greater spacing of the rods. It's not necessary to do it however one thing you do NOT want to do ia create a long ground path thru your house between two ground points that are to be connected together. Lightning is best kept outside at all costs. Also check out W8JI's site regarding grounding. He has some excellent ideas imcluding a better explanation of the pwrimeter ground.