[Elecraft] Grounding & Receivers

[Don Wilhelm]

----- Original Message -----
>
> What types of grounding do most use on the K2?  I want to be able to
> operate from second story and grounding is a problem with higher
> powered rigs...does the K2 have this problem?
>


Dudley and all,

I will jump in here with one of my hot buttons - Grounding!!!

RF ground is not the same as AC ground is not the same as Lightning ground
is not the same as Earth ground!!!  (But they CAN be the same - they DO
function differently and for different purposes).

The ground pin on your AC receptacles should take care of any AC grounding
concerns assuming that your house, apartment, etc. is wired in compliance
with NEC standards of the past 30 or more years.

There is no need for an RF ground on any receiver.  The need for an RF
ground comes into play with the antenna system.  If you are using a truly
balanced antenna system, one side of the antenna system works as an RF
ground for the opposite side.  If the antenna system is unbalanced, an RF
ground must be provided somewhere in the radiating path - and that point is
usually not at the transmitter/receiver - it is things like the ground
system for a vertical antenna or the counterpoise on a ground plane antenna
(just because it has ground in its name does not mean that it needs to be
connected to earth ground - it acts as the 'ground' reference for the
vertical {or other} part of the antenna).  In some installations (like an
end fed antenna), the antenna feedpoint is brought right into the shack and
connected to the transmitter/reciever and this is the situation when an RF
ground must be provided right at the transmitter/reciever.  That kind of an
RF ground could be provided with quarter wavelength wires - one for each
band of operation.  (The quarter wavelength wires also are often used to
cure difficult cases of "RF in the shack" in addition to any normal RF
ground reference)

Lightning ground is a whole different consideration - lightning contains
Mega-Amps of current  over a very wide range of frequencies (DC to Daylight)
and requires really fat multi-wire conductors to provide a path for a direct
hit and this much power will make its own path - most anywhere it wants and
finds easiest.  The normal ham cannot afford really good protection against
a direct hit - leave that stuff for the commercial radio installations.  The
best advice is - do not operate when a lightning storm is nearby AND get
those antenna feedlines outside.  Even lightning many miles away can produce
a very large voltage across an antenna feedline - the antenna is capable of
picking up RF - and lightning contains a lot of RF itself which can be
induced into the antenna system.  Yes, do ground those feedlines when not in
use - the best thing is to ground them outside and ground them to a GOOD
earth ground.  Install lightning arresters on any feedline just to be safer,
but do not depend on them - there will not save you or your equipment in the
event of a direct (or very close) lightning strike.  If you are in a second
floor apartment, this part could cause you a problem to implement properly,
and when faced with a similar situation in times past, I simply put the
feedlines outside and crossed my fingers.  Get a good earth ground
connection outside the building the shack is located in for this purpose if
you possibly can.

OK, soapbox off now- just be safe and understand the limitations of your
grounding system.

73,
Don Wilhelm  - Wake Forest, NC   W3FPR home page: http://www.qsl.net/w3fpr/
  QRP-L # 485   K2  SN 0020   mailto: w3fpr@arrl.net