On Wed, 06 May 2009 02:34:45 +0200, noname wrote:

panel ground. Can YOU find that ground?


I don't understand your question. The radio chassis is grounded to the
wall outlet. The overall house wiring was recently inspected, with the
grounding checked at that time. It was a thorough inspection which
also included a device plugged into most outlets to check the wiring.
Given that, I don't really know what I'm supposed to find and why.

Hi Stewart,

If you are going to add a ground, it has to go to the ground electrode
- it is called service ground. That is located in very close
proximity to the fuse box - it is called the service panel. Close
inspection (by you) should reveal it. It may be a wire tied to a cold
water feed from the city services.

So, by this explicit statement, your "balanced" antenna
has been unbalanced at the rig (which only further enforces
the unbalance by virtue of the coax connection).


I guess so. Actually, I don't really know. The radio was manufactured
with the chassis grounded to the wall outlet and the antenna was
designed by it's manufacturer to work properly with 50 ohm coax feed
connected (I would assume) to a radio like this. What impact that has
on balanced versus unbalanced is beyond me, and the same is true for
what exactly you want me to do about it.

A purist's balanced antenna is connected to a twin lead, or open wire
pair. This transmission line goes to the purist's special tuner with
a balanced connection. Many cheap tuners pretend to offer this
option. Expensive tuners the purists use pretend to do it too. At
some point, one of those two wires (if you were using twin lead) would
go to the chassis. This would make it unbalanced, and this unbalance
would be cast back into the antenna making it unbalanced. There are
tuners that do it right, but you have to look under the hood and
verify their claims.

Using a coax means you are using a conventional connector with a
collar (bayonet style or screw type) that connects directly to the
chassis. BINGO! Your system is unbalanced. But it was unbalanced
before it got there, and the connection only enforced it. The coax
offers what is called the "third wire" to the dipole with its shield
(the shield exterior is a separate circuit to its interior circuit).
When you use a coax with a dipole, you are making it a tripole, with
one leg of indeterminate length. You can reduce the third circuit
path effect through choking.

If you cared about the state of balance, then you can take steps to
reachieve balance. One is to choke the feed point at the antenna, and
then choke it again a quarter wave down from that point. You can (as
suggested by Jim) choke the ground as well. You can (as suggested by
MFJ) choke the transmitter end of the coax. Each brings an additional
degree of isolation, and attempts to bring balance. Unfortunately,
balance is also a function of what physical distance and bulk
relations each arm of the antenna sees. Nature and homes rarely exist
with perfect symmetry (another name for balance) to serve an antenna.

You could add a chimney stack to the other end of the house, and
rearrange furniture (and occupants) inside to help, but life is short.
Got trees? If you are operating 80 meters, anything within 100 feet
is fair game for the balance sheet.

As for impact, there is every chance you don't need to do anything but
insure a good safety ground. If your chassis bites you during
transmission, then, yes, add some chokes (see thread). If your
antenna picks up signals from directions you had pointed the antenna
away from, then, yes, add some chokes (see thread). If you cannot
tune the antenna on some bands, maybe (just maybe), add some chokes
(see thread).

73's
Richard Clark, KB7QHC