On Mon, 18 Aug 2003 23:11:04 -0400, Bob Brock
wrote:

On Mon, 18 Aug 2003 21:26:20 GMT, erniegalts
wrote:

On Sun, 17 Aug 2003 00:02:39 -0400, Bob Brock
wrote:

On Sun, 17 Aug 2003 03:39:14 GMT, erniegalts
wrote:

On Sun, 17 Aug 2003 03:03:05 GMT, "mad amoeba" wrote:

Not difficult to get an amateur license these days now that the code
requirement has been wiped. Anyone who knows a bit about radio should
be able to study the regs and pass an exam allowing VHF operation on 2
metres, and the "general class" [ or "full call" ] exam is not that
much harder.

General Class license still requires a Morse Code test. Morse has not
been "wiped." It has however, been lowered for the two higher class
licenses from 13 and 20 wpm to 5 wpm for both licenses. Morse is not
required for the Technician license which give full priviliges on
VHF/UHF.

So, once again ernie, you are wrong.

http://www.arrl.org/pio/hamlic.html

Which states:
The General License:

The General class license grants some operating privileges on all
Amateur Radio bands and all operating modes. This license opens the
door to world-wide communications. Earning the General class license
requires passing a 35 question examination. General class licensees
must also have passed the Technician written examination and the five
word-per-minute Morse code test.


Just had a look at it. You might check the date at the bottom.:-)

Page last modified: 09:55 AM, 27 Sep 2000 ET
Page author:
Copyright © 2000, American Radio Relay League, Inc. All Rights
Reserved.


The Amateur Extra License:

The Amateur Extra class license conveys all available U.S. Amateur
Radio operating privileges on all bands and all modes. Earning the
license is more difficult; it requires passing a thorough 50 question
examination. Extra class licensees must also have passed all previous
license class written examinations, including the five word-per-minute
Morse code test.

-----------------------------
So ernie,where specifically was I wrong? Code has not been "wiped."
It's been reduced to 5 WPM for the two higher class licenses required
for operation on the HF band.


Sorry, Brock, it is you that are wrong, and for the second time in a
matter of weeks. First time was when you accused me of being unable
to calculate the resonant length of a 1/4 wave vertical.

It was the part where you said that automobiles have quater wave
antennas that resonate at around 500 KHz. That my boy is a hell of an
antenna for a car.

Show us where I said that. I said that this would be the resonant
length for an antenna of that length.

Never mind, I'll look it up and reprint text in full, snipping some
excess material from full header. ###### My comments set off by hash
signs as usual ######

=====================================
From: erniegalts
Newsgroups: misc.survivalism
Subject: Radio technical question???
Message-ID:
Lines: 150
Date: Mon, 21 Jul 2003 02:37:18 GMT
NNTP-Posting-Date: Mon, 21 Jul 2003 12:37:18 EST
----------------

On Sun, 20 Jul 2003 16:14:19 -0700, Louis Boyd
wrote:

Steve Day wrote:
Ok guys and Gals, here is one for the more technically minded of you )

If I want to try and improve the reception on my car radio or home based SW
radio (to for example pick up weather broadcasts or news broadcasts in a
remote location), the normal route is to extend the length of the ariel ????
How ever when I have tried this with my Roberts 886 world band all I get is
more very loud interference.

So how do I extend the length of an ariel using a wire to improve reception
without picking up more interference?



Just extending the length of the antenna doesn't usually get it away
from the noise sources and make actually make the signal to noise ratio
worse.

1. Eliminate the noise sources if practical. Things like fluorescent
lights, dimmer circuts, some UPS's etc generate considerable noise in
the AM and SW bands. This may not be practical if the interference is
from other than your property, but I've had success in finding
capacitively sparking connectors on power poles and asking the power
company to fix them. I've never seen them find the problem themselves
as such sparking isn't considered a power fault. You can track it down
with a portable radio and see exactly where it's sparking at night. A
NV scope make the sparking easy to see. On a car radio check ignition
noise first. Noise can also come from corroded metal acting as a mixer
causing noise to be generated from nearby transmitters which are working
properly.

2. Move the antenna away from the noise sources. Whether that's
practical depends on the radio's input circuit and it's provision for an
external antenna, and of course where the noise source is located.

3. Get the antenna to a higher elevation. That's most effective at
higher frequencies, not so effective at AM and low band SW.

4. A larger and more directional antenna may help. A shielded loop
antenna can be oriented to null out a single interfering source on the
AM and low SW bands. At high SW frequecies a directional multielement
antenna (or other designs) may help but such antennas are large below
VHF frequecies.

All good advice. Can get inline boosters for car radios, but as Lou
points out won't help the signal to noise ratio.

On car radio, are you talking about AM, SW, or FM?

The best non-directional antenna is one that is resonant at the
desired frequency, and the metric formula for this is very simple.

The usual whip antenna on a car is a quarter wave vertical operating
against a ground plane. The formula for resonant frequency for a 1/4
wave antenna is 75 / frequency in MHz.

####### Now Brock, point out where this claims that the quarter wave
antenna on a car is anywhere near resonant frequency. If you are
going to criticise my posts at least try to read them carefully enough
to get the meaning and stop jumping to conclusions. Better yet, why
don't you simply killfile me??? ######

Using a resonant antenna is very important for transmission, but also
quite significant for reception.

So lets assume that you want to listen to an FM station at 100 MHz [or
megacycles] on a car radio. Resonant length in metres for 1/4 wave
vertical would be 75/100 = 0.75 metres = 75 centimeters which in
imperial measurement would be 29.53 inches.

##### Which is roughly correct #####

Easy to see that this no problem for a car antenna. However, suppose
we are talking about a SW radio for 27 MHz CB? 75/27= ~ 2.77 metres,
=~270 centimeters = 106.3 inches = ~ 8.9 feet.

If want anything near perfect resonance and omnidirectional coverage
for an 8.9 foot vertical need at least as much ground plane or radials
at the base of it to form a "counterpoise" [More or less of an
"electrical mirror image" of the antenna, or "the other half of it".]

###### This is also reasonably correct ######

However, highways aren't designed for vehicles almost 18 feet wide, so
will have to accept some compromise.

#####The reason isn't only the ground plane, of course. Most overhead
structures such as roof over pumps in service stations and many
highway overpasses, pedestrian bridges, etc. don't allow for height of
vehicle roof plus ~ 8.09 feet#####

Much worse at AM frequencies, of course. AM band runs from around
..53 to 1.6 Mhz, or 530 to 1600 Khz. So for an AM station at 1000 KHz
or 1 MHz, the resonant length would be 75/1 = 75 metres.

One foot = 0.3048 metres, so 75 * .3048 = 22.86 feet, the length of
your resonant vertical, so if you mounted it dead center in the metal
roof of your vehicle, the vehicle would have to be 45.72 feet wide.

[Yes, can get by using physically shorter resonant antennas by
winding this as a helical coil on a physically shorter form, but
efficiency falls off drastically for shorter lengths.

If assume that the feedline is correctly matched to an antenna of the
proper length, and had enough surrounding metal around for it as a
ground plane efficiency might approach 100%.

For 27 MHz, can wind that 8.9 feet if wire on a 6 foot long form, but
your ground plane still wont be adequate, so efficiency will probably
be 70 or 80% at best. Can even wind it on a 2 foot form, but then
efficiency will drop to around 10%.]

Yes, going into more detail here than is necessary, but there may
be some people still fooling around with 27 MHz CB in the group.

#####Which is why went into such detail. But again note that there
is no claim in the post that the 1/4 wave vertical receiving antenna
on a vehicle is anywhere near resonant at lower frequencies.#####


OK, for reception you don't need a fully efficient resonant antenna on
your vehicle, and no need to try to match to it. A long helical wound
fiberglass antenna may be the best you can do.

Now if talking a fixed station antenna, you have a lot more
flexibility. You can go for long wire antennas, quads, or even
rhombics, terminated or unterminated. [For details on such antennas,
see current ARRL antenna manual]

Nice to know all this stuff, but if the average SWL listener my
personal advice for broadcast band or shortwave is an active antenna
such as a Datong. Basically, a wideband 1/2 wave dipole with
switchable gain.

##### The tapered stainless whips on the datong dipole are nowhere
near resonant lengths for most frequencies either. From memory, about
5 1/2 feet long. ######

Used vertically, it is omnidirectional. Used horizontally, highly
directional, so useful for nulling out noise sources.

##### Can be mounted on larger vehicles for mobile reception #####

Searched the web for
Datong active antenna
Results 1 - 10 of about 189. Search took 0.17 seconds.

Hope this will help.

However, I don't claim to be an expert on antennas. Others on the
group would know more than I do.

Generalists are, by definition, generalists.

People like Gunner have claimed to be "generalists" but in some areas
obviously have some areas of specialization. For example, he would
know far more about metalwork than I would.

And if you wanted to know more about propaganda, lies, killing, and
general asshole behavior, would probably be difficult to improve on
this particular resident of California. :-)

Although I suspect that he is now known nationwide or even worldwide.

erniegalts


I would ask if you are this stupid, but I know that you aren't.
You're just a troll ernie and not a very good one.

When want you opinion, Brock, will ask it.

.....And you are still in error on both the resonant antenna and the
requirement for morse. :-)

erniegalts