Jim, first off, no argument intended! Just discussion! Perhaps my use of
caps????
Anyway, my original post was to answer the guy's question about a simple
receiving antenna for his weatherfax on a small sailboat...thus my comments
on my experience with receive ONLY antennas.
YES....receive only antennas and antennas that are required to transmit AND
receive are different. More on this in a moment...
As to the fact that broadcast stations were easier to copy then weatherfax
stations at THAT given time, location, propagation, and goodness knows other
factors....there is no surprise to me....BECAUSE of so many factors
involved. I'll be willing to say that the transmitter power of those fax
stations was FAR less than the comparable broadcast stations....but that
would only be ONE factor describing your reception at that time, location,
propagation etc... See where I am going? Impossible to predict
everything, or explain everything in long-distance radio.
By the way, FINTRY is one gorgeous boat! I had a look at her on your site
to see where (I) would put an HF antenna. Here's what (little) I know as a
sailor: First....your boat looks like a trawler...a general description of
this style boat, that has become VERY popular with serious motor-cruisers as
of late. You are going to find many other folks with HF stations on this
style boat...and I would sure get in touch with some of these people to find
out what THEY are using. I'll bet most use a WHIP antenna.....but the true
rule-of-thumb for an HF antenna is to go as LONG as possible to get the best
performance! MY GUESS would be to go with the (insulated) WIRE for the
reason of LENGTH alone.....but this wire at 20 degrees off of the horizon
might not give you all of the "local" (50-200 mile) performance you might
desire, due to polarity being mostly horizontal, and MOST other marine HF
stations antennas out there being polarized somewhat vertical. Someone
(hopefully from EXPERIENCE) may comment on NVIS and other factors to support
/ poo-poo my thoughts here....PLEASE DO! That is why I titled the post that
way....hopefully other "trawler" style boaters will contribute something.
The BEST signal I have ever heard coming from a boat (given the distance and
propagation conditions at the time,) was from a STEEL sailboat with a 33ft
!!!??? whip off of the transom, according to the operator. 33ft whip? Who
makes such a beast....I've never seen or found them advertised. BUT...a BIG
doggone whip well supported up on that wheelhouse might be the ticket! NOT
the little 23ft whips commonly available....
It seems that you know something about a proper capacitive ground, and it's
ABSOLUTE NECESSITY for a good TRANSMIT signal....she's a WOODEN boat, eh?
Build the most elaborate ground you can, with AS MUCH area below the
waterline (and bond the engine, tanks, metal through-hulls ad nauseum) as
you can. Whatever long antenna you choose, the ground will be the MOST
IMPORTANT factor in signal output besides the transmitter and antenna tuner.
Take the ground stud of the radio itself to some point in the ground with a
wide copper foil (as well as the tuner,).....the tuner should be as close to
the FEED POINT of the antenna as possible. Bring AS MUCH of the ground
complex to the ground of the tuner as possible, using multiple legs of
copper if need be....with the tuner as the "apex." Steel yachties have it
easy....and often have the best signals on the water....a near perfect
ground with the whole damn hull for signal to "push against."
LEARN TO USE the antenna tuner properly. MOST of them will bypass the
"tune" function in some way....most common is to cut the power to the tuner
and then turn it back "on". (THIS circuit breaker goes separately right next
to the radio operation position, if the electrical panel is elsewhere!)
Puts the tuner into a "bypass" mode in which the transceiver is connected
directly to the antenna. Try this for reception when tuning across
different bands looking for something. That way, you are not tuned to only
the last frequency in use....to the detriment of others (sometimes, to the
detriment of others in the same band!) If your "tune" button on the
transceiver works (hopefully with very low TX power) on all
frequencies....in theory...if the tuner tunes to resonance...it should
RECEIVE better while tuned....but is easier to find a broadcasting station
in the bypass mode FIRST. I am by no means suggesting that you should
transmit (even for a second or two, even at low power) on frequencies that
you are not licensed on. THAT'S what the "bypass" feature is for!
Hope this helps just a little bit, as I'm no "expert" either, Jim! There
are quite a few guys on this group that will contribute more direct answers
to your good questions, and if I've scared them up from the deep...I have
done OK!
Good luck with that wonderful boat!
Joe