[Elecraft] Noise Problems...still

[Don Wilhelm]

Terry,

It does sound like you are making good progress.  Take things one step at a
time and you will get up to speed - don't try to rush it.

Are your tuned radials right on the ground?  If they are, the proximity to
ground will de-tune them negating all your hard work!!!  If you can elevate
them to about 7 ft (above head height), then tuned radials are a good thing,
but if they are right on the ground the length is not critical - on the
ground you are just trying to produce a good conductive ground screen out
from the base of the antenna, so any length about 1/4 wave or more for the
lowest band will do.  If the radials are elevated, it is important that they
be tuned in relationship to the vertical element for each band.

Relating your ground system to noise pickup may be like comparing apples and
oranges.
It just might be that the ambient noise level at your location is high and
you will have to work around it.  If you have a high noise level, your
antenna proper may be picking it up and no amount of decoupling will
decrease it.  There are techniques for cancelling out noise pickup by
phasing methods, but adjustments are usually quite 'touchy' and require a
separate noise pickup antenna - you may have to resort to similar techniques
in the end, but get your main antenna system in shape first.

As an entirely different matter, your station ground system (20 ft long
copper wire) is just fine for DC and some small measure of lightning
protection, BUT it may not be providing you with a good RF ground.  Usually
the poor RF ground at the shack will show up as some RF in the shack
(metallic things 'bite' you when you are transmitting or you will get some
strange feedback 'happenings').  You can add to your ground system with just
some wire - a piece 1/4 wavelength long at each band you will operate.
Connect the near end to your station ground and run the far ends anywhere
you can.  If you need to run them in parallel, separate the ends by at least
a foot.  NOTE WELL - there may be high RF voltage on the far ends of these
wires, so insulate them just as you would for an antenna end and keep them
out of reach of others who might walk near them.  It is good to run them
straight, but not necessary, but don't make any sharp bends (use a long
radius if you must turn them).

 These wires have a high RF impedance at the far end and a low RF impedance
(ideally zero) at the shack end due to the voltage/current transformation of
a 1/4 wavelength wire. Try it and see if it helps - it certainly can't hurt
anything.

73,
Don W3FPR


----- Original Message ----- 
>
>      Well, the noise level has been lowered a lot, but I'm still getting
> higher noise levels than I think I should.  On 40-meters, I am getting an
average
> of S2-4 peaking at S5 around the time thunderstorms begin to form.
>
> I've put up a vertical which helped.  Putting down 12 tuned radials, 2 for
> each band, helped even more.  Moving the power supply a few feet away may
have
> also made a difference but I can't tell by ear.
>
> I am using the standard red/black zip type supply line from the power
supply
> to the radio.  I am wondering if going to coax to supply power to the
radio
> may not drop the noise level even more?  I would think that the R/C tank
in the
> radios power circuit would take any ripple or noise out but maybe I'm
wrong.
>
> I also have a ground that is a 20' long piece of 10GA bare copper wire
> running to a single lightning rod from a second story window.  I'm now
wondering if
> this wire isn't acting like part of the antenna or maybe injecting my
> transmitted signal back into the receiver via the power supply.  Since I'm
only
> running 5-10 watts output, should I use coax for the ground as well and
decouple it
> with ferrite beads just in case?
>
> For a beginner, this is all pretty confusing!  I read so much, trying to
come
> up to speed quickly. The problem is that I begin confusing which solution
> goes to what problem I remember reading about last month in some
periodical
> can't remember.
>