In , "Randy" wrote:
snip
Just so I am clear about one thing .... In all of these articles that I
have been reading, when they talk about grounding the antenna, they are
referring to a RF ground (ground plane) and not a physical ground? If for
some reason the shield is not grounded would this be my problem?
Close. Whine is RF interference from the engine electrical system (and sometimes
other electrical devices like the fuel pump) and occurs on almost all vehicles.
The difference is that an engine compartment which is fully enclosed by metal
will shield the radio and coax from this noise (the noise can also pass through
the electrical system, but that doesn't seem to be your problem). If you have a
fiberglass hood, or if your coax passes through the engine compartment, the coax
must be grounded at the radio end or it will pick up this noise just like an
antenna.
An RF ground is both an electrical ground -and- a physical ground. It is a
low-impedance path for RF and is very dependent on the physical properties of
the connection. Usually, a good RF ground is any point where electricity can
easily take many different directions -- kinda like ****ing into a lake. Just
about any point on the chassis will be a good RF ground. A single wire to the
chassis is a better antenna than an RF ground. For example, if your radio is
grounded with a wire longer than just a few inches it will allow RF voltage to
develop on the radio chassis, and the radio effectively becomes part of your
antenna system. That makes it very suseptible to engine noise and other types of
RF interference that may be picked up by the coax shield (which is connected
directly to your radio chassis) or passed through the electrical system to your
power leads. So by RF grounding the radio (and therefore your coax) you are
shunting all that RF interference to ground so the radio doesn't have to deal
with it.
Not having a good RF ground at the antenna can screw up your SWR, but that's
about all. It's much more important to ground that radio!
My boss will not care that this unit has a whine. I am not sure he would
care whether it has a CB or not. I had to take the truck down to the shop
last week to get the steer tires balanced, I had to pay for everything. He
is not a bad guy ... just cheap!
If it's a business expense it should be paid for by the business.
The unit might not be grounded very good. It sits in an upper header
console, just strapped in not bolted. I will ground the unit and purchase a
noise filter then adjust my antennas.
The upper header console is a terrible ground if your roof is fiberglass. I
would recommend mounting it on the dash or the hump, close to the chassis. That
will require rerouting the coax, but at this point that seems unavoidable.
I tried reading as many articles as I could but they all were saying the
same things and some of that I could not understand. I thank you for your
time. I will let you know if the problem persist after these changes.
Thanks again
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