On Thu, 18 Aug 2005 10:54:21 -0500, (Richard
Harrison) wrote:
Thank-you Richard for the prompt reply, which I am afraid I understood
little of (! my fault not yours)


Stephen Parry wrote:
"I drive a truck on the continent of Europe, and would love to listen to
this service on the road for cricket."

The Blau Punkt in my Karman Ghia got such signals all over the
continent, and I`m just one of millions.

Mr Parry did not say if his truck is Diesel powered as most European
trucks are.
Yes Diesel power, so no HT coil, plugs, distributor etc
If so, he is free of his own ignition noise, usually the
hardest to suppress.
Ok.
He still may have alternator whine (perhaps a bad
diode)
Yes I think I do have alternator noise could you explain what I might
do ?
and he may have static discharges from things which rotate. Some
are under the hood, and their radiation should be kept under the hood by
the metal surrounding them. All such metal pieces should be bonded
together to keep the trap they form closed.

All conductors coming through or under the firewall should be well
grounded or bypassed with capacitors at the firewall. The exhausr pipe
may need bonding here also.
I think we might have been divided by our common language! My truck
has no "hood" as such http://www.duet-duda.mojagielda.pl/?9

Maybe there is a gasoline powered rerfrigeration compressor generating
ignition noise. Standard resistance wires, capacitors, and bondibg
should silence that.
No 'fridge
Springs can be used in wheel hubs to ground out static.
I did not understand this part

All the metal parts of the truck may have to be bonded together.
Or this

My Blau Punkt was equipped with a good sized choke coil in its battery
lead. It also had an internal "spark-plate" capacitor, and these rid the
power source of radio noise.
Or this

The telescoping antenna (about 50 years ago) could be extended to about
100 inches, which made the Karman Ghia quite a sight, but it worked. The
antenna cable was the standard high-impedance small inner-wire coaxial
type. This must be intact and perfect to keep the signal on track and
the noise out. Though German, it used Motorola connectors.

Radio frequencies decline very rapidly near their source. This is your
friend when the source causes interference.
Sorry, this too!
Keep the antenna away from
and shielded from sources of interferebce.
When you say "bonding" I am guessing this means a clean earth return
to battery?

In 1935, Alfred A, Ghirardi (E.E.) wrote:
"---an aerial must be installed in (or on) the roof, under the running
boards or chassis of the car, or in some other locations.
---Considerable attention must be given to the ignition and other
electrical wiring of the car in order to eliminate all electrical
interference which it produces in the receiver."

Noise problems are more often caused by the vehicle than by the receiver
but some receivers may not be shielded and filtered well enough. If the
truck cab has its pieces bonded together and all pass-through conductors
are well bonded or bypassed, it should be electrically quiet. You should
be able to use a portable radio in there with proper placement or an
outside antenna.

Ghirardi devotes an entire chapter to automobile radio installation in
"Modern Radio Servicing". Car radios are hot in the summer months while
home radios are not.

Best regards, Richard Harrison, KB5WZI