PSN-L Email List Message

Subject: Re: Ham radio interference
From: Thomas Dick dickthomas01@.............
Date: Sat, 20 Feb 2010 14:08:17 -0600

Again good points .... Jim Santee:
> Experiment with "by-pass" capacitors on the input to your seismic monitor.
My coils are 220v relay coils. I have at least one unit with the .01 
capacitor on it. I will check the rest. I don't think the AS-1 has any. 
I also used 1/4 inch metal square fencing to make a cage to put around 
one of the units.
> A good quality AC power line filter on both units - seismic and 
> transceiver. One problem that you might check into is what is called 
> "an elevated ground". 
I have heard of that. Will check

I have four six foot copper coated rods in the ground. I don't remember 
what kind of wire is on the tower ..but I know it IS grounded. Strange 
though ..... I have been hit by lightning twice. It cause over a $1000 
damage to TV sets on the cable system in the house (I think this was 
induced current coming in on the cable line) In both cases, witnesses 
described "ball" lightning rolling off the ends of the guy wires that 
are attached  to four inch metal posts at the four ends of my lot. The 
ball lightning traveled at least fifty feet along the ground. The first 
hit took out the commercial grade antenna at the top which vaporized a 
#8 wire coil. Neither damaged my radio equipment.... It did blow a small 
transistor in the 10 meter repeater identifier.
> This is where your transmitter is grounded, but not truly grounded - 
> confusing YES!. I have had to chase grounding problems in complex 
> communication systems and this be frustrating. You start by making 
> sure you have good quality grounding straps - I use the term straps to 
> indicate 1" wide tinned copper braid or 1/16" thick x 1" wide flat 
> copper stock in lieu of just a piece of wire. Fine stranded welding 
> cable or high quality automobile battery straps have been used for 
> grounding applications. Circular grounding wires can sometimes 
> "radiate" and cause interference. Each and every grounding point needs 
> to be cleaned and "no corrode" contact improver smeared on the 
> connection points. You can get "no corrode" at electrical supply 
> houses. Power companies and electrical contractors use this all the time.
> Now for the fun stuff: When you connect grounds, or any else for that 
> matter - make sure that you are not causing your own problems by using 
> dissimilar metals. For example, don't mix carbon steel hardware with 
> copper wire. In the 1970's a common practice in residential 
> construction was to use cheap aluminum wire in lieu of copper. Over 
> the years the aluminum wire expanded and contracted at different rate 
> from the contacts on switches and outlets - this created a "high 
> resistance" contact which later heated up and caused fires. Last 
> summer I had help my neighbor on this same issue - she is lucky she 
> did not have a house fire.

My house was built in 1946. All wiring to the ham rig area is new ... 30 
amp to a new meter system.
> Here is a grounding story that went bad by design: I use to work on 
> marine radar systems. The system engineer never considered that "his" 
> pride and joy would ever have a problem. It seems that the engineer 
> ignored electrolysis - he spec's called for aluminum waveguide to be 
> connected to brass waveguide with steel screws - all on a boat in a 
> salt water environment. Within six weeks the entire assembly was 
> corroded beyond repair. In another application on an aluminum hull 
> vessel the engineer had an HF radio connected to the hull using a 
> copper grounding strap with a steel bolt - this was a real mess and 
> caused considerable damage to the hull.
I used to own a 36 ft CrisCraft boat ..... the last year they made 
wooden hulls (1969). I wouldn't own an aluminum hull. I had enough 
trouble with the battery charger  pitting the bronze propeller blades.
> One point in closing: Power line ground is not always "ground" for RF 
> purposes. Power line ground is for safety purposes only and not for 
> RF. You may need to install your own ground rods.
Thanks for your input!!


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