HF Antenna for reception.

[Bruce K]

I am trying to receive weather on a Sangean ATS 505, from VMC in Charleville Aust. Attached whip is not great, now using a wire antenna via ext ant jack, any advice from HF gurus on length, this is receive only. Difficult to get much height, as I have no mast.

[El Pinguino]

Do you have the 'wind up' ant that came with it?

When listening to my small radios outside I unwind about 5 metres and hang the end at about two metre altitude in a tree next to the table, works good.

I don't know the 505 but the 909 and 909X are well known for being profoundly deaf on HF when using the whip but are great with a wire ant.

[Bruce K]

I don't have any trees on my boat, suppose I could plant one and wait!!!!!!!!!!!!
Radio is about 15 years old, I will look for the antenna, but I have a jack plug that fits, with soldered wire, it seems no better than the whip. I thought there may be a specific length for improved reception?

[El Pinguino]

Originally Posted by Bruce K

I don't have any trees on my boat, suppose I could plant one and wait!!!!!!!!!!!!
Radio is about 15 years old, I will look for the antenna, but I have a jack plug that fits, with soldered wire, it seems no better than the whip. I thought there may be a specific length for improved reception?

Ah...brain phart on my part...sorry...was thinking shore side mast to support ants.

Don't think receive needs any particular length.

Don't wait for tree to grow... just get a bit of a tree and use that....dja have a boathook? lash to stanchion.... will work.... in fact laid along cabin top will work.
Once with no mast used a spinakker pole to support long wire and used that for tx/rx.

[Paul Elliott]

Most of the time a receiver doesn't need anything more than a fairly short random antenna. A specifically-tuned antenna will give you a stronger signal, but it will also give you stronger noise as well. The simple test is to unplug any antenna and listen to the noise your radio is receiving. Then plug in the antenna (wire, whip, whatever). If the background noise increases in level then the antenna is probably good enough.

Caveat: by "background noise" I mean atmospheric noise or static, not noise created by your on-board electrical or electronic devices. If there is any question about this, switch off all power to any potential noise-creating devices: LED lights, refrigerator, engine alternator, computer, etc, etc.

[El Pinguino]

The beauty of a portable is that you can sniff out 'on board' RFI with it...

[W3GAC]

Before doing much else I would try other boats/ radios in your immediate to see if they can receive this station. It just might be you are too far away/ not a good propagation time of year or your portable radio just might not have enough sensitively to pull in its weak signal.

Receiving a signal is all about getting having enough sensitivity and receiving enough of the desired signal stronger than receiving all the local 'noise'. Can't do much about atmospheric background noise but as another poster said, if you have high local boat/ neighbor generated noise you might be able to locate/ remove it. If you are in a marina, this is almost impossible because there are just too many noisy 'switching technology' battery chargers running on unattended boats, led lights, flat screen TVs, cell and other charger wall warts. I have a very good 65' long insulated backstay and quality SSB marine/ ham radio equipment but I have to almost forget trying to operate HF amateur radio at my marina.

If you do the test of connecting/ disconnecting your antenna while listening to noise level and don't hear a big difference/ high noise, then either your receiver just doesn't have enough sensitivity or there just isn't enough station signal (can vary with time of day, season, 11 yr solar cycle.

It actually does matter about length (and height) of the antenna. In some respects longer is better, but there actually is an optimum length: 490 / Frequency (expressed in MHz) = length of a dipole... divide that number by 2 if your antenna is going to be a vertical wire pulled up flag halyard/ mast. That formula calculates the antenna length for a resonant antenna. An antenna will increase its effectiveness in receiving a station at its resonant frequency. It's receiving energy transfer goes up and all other signals are received a little less as good. If you decide to make a resonant vertical antenna, it would help if you used coax cable attached to the bottom and pull the active/ resonant part of the antenna up as high as possible. This will increase reception and move the antenna further away from possible local interference noise.

I don't know the specific radio you are using. If the external antenna jack is designed for coax the center pin will be the actual antenna input and the outer part will be for the coax shield/ ground. If the coax shield is not 'grounded' to the connector's ground all your extra effort of building a resonant antenna/ getting its active part up and away from local noise sources will be for nothing. Also, having your radio's 'floating' ground actually grounded to the boat's ground can greatly increase receiver performance.




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[roland stockham]

I have had good success by simply tying a wire to the guard rail and using that as the aerial, worth a try!

[Tikka]

Hi Bruce, Short waves listening are always marginal unless you use proper gear. I used to listen Charleville, different time of day, different frequencies.
You don't have mast use Marine Radio antenna and twist 10 m wire or perhaps try
safety rails, it's all abou the aerial surface. Wavelength between 40 -160 metres, frequencies for Charleville are just too long to get some wavelength dB advantage.

[svserengeti]

Bruce,

Just connect your antenna on the shortwave radio to your standing rigging on the sailboat & you should have great reception. I used alligator clips and a short piece of wire to the chainplates beneath the deck. It worked great!
Cheers

[ka4wja]

Bruce,
Before you do anything else, be absolutely sure you have your 505's "SSB" switch ON....it is on the side, just above the headphone jack.
(I use a ATS-909, and it works great....but, have never seen/used a "505"...)

I'm not sure of your exact location, nor intimately familiar with where you will be sailing, vs. VMC....
But, in general VMC is about ~ 550 - 600 from "NSW Central Coast"...

So, your first two steps are:
a) determine what freq to tune to for the distance...
b) determine what freq to tune to for the time-of-day...

I would try 11030khz and/or 13920khz, daytime....(typically from about 2 hours after sunrise, to about an hour after sunset...)
also try 5100khz in early morning and late afternoon/evening...

For nighttime, try 5100khz, and 2628khz....

(in brief...11mhz daytime is primary and 5mhz nighttime is primary)

Originally Posted by Bruce K

I am trying to receive weather on a Sangean ATS 505, from VMC in Charleville Aust. Attached whip is not great, now using a wire antenna via ext ant jack, any advice from HF gurus on length, this is receive only. Difficult to get much height, as I have no mast.

Just about any length of wire, between 15' - 40', will work for you....but, if you wish to optimize things, try 20' for the daytime and maybe double that length at night...BUT...
But, it is NOT critical at all!!!

And, if you have no mast???
Try just supporting this wire above the deck, horizontally, keeping it about 15' - 30' above the water...and you will have a great receive antenna!!!

If you had a mast, I'd say just clip a short wire from a shroud / backstay to the radio's ext. antenna jack...
But, without a mast and rigging, try the wire I describe above...

Australia Weather East - Charleville ( VMC) Specifications

VMC & VMW Radio Fax Schedule

HF Marine Radio Services



But, the keys here are:
a) Getting away from all the RFI (Radio Frequency Interference) / radio noise generated by so many consumer and industrial sources!!!
Try your radio when at least 1/2 to 1 mile offshore / away from civilization....

b) Ridding your own boat of offending RFI...(see the links on both SSB receivers / receive only, and links about RFI, in the "sticky" right at the top of the Marine Electronics page)
http://www.cruisersforum.com/forums/...tc-133496.html


c) Knowing when / what freqs to use (see above and the videos linked to here..)


d) Please have a look at these videos....not 100% on point for your application in Aus, but pretty darn close!!!

https://www.youtube.com/playlist?lis...zdjTJjHlChruyY



https://www.youtube.com/playlist?lis...ZDo_Jk3NB_Bt1y
(especially watch the first video here in this playlist, to get an idea of how radiowaves propagate on different frequencies / times-of-day...)



Bruce, once you've read the above, read the links, and watched the videos....you should be good to go!


Fair winds..

John

P.S. I haven't tuned in VMC / VMW weFax transmissions in a while....but, I DO use their Voice Weather broadcasts (on 12362 and 12365, daytimes, and 8176 at night) as my "test" of how good radio propagation conditions are for me around the world....and remember, I'm > 9000 miles away from VMC, and about 11,000 miles from VMW....

[Jim Cate]

FWIW, on the central NSW coast, I have found that in the morning (2030 Z for the MSL wefax broadcast) either t he 5 or the 11 MHz signal will work. And sometimes, the signal from the Wyuna station out west will be better. Later in the day either the 11 or 13 MHz frequency will work.

But, there well be days when none of the above are correct... HF propagation is subject to lots of physical variables, and the whim of the gods as well!

73

Jim

[El Pinguino]

With that radio I would be sticking with HF Voice to start with... daytime 4426, 8176, 12365, 16546... and making sure they are transmitting when I am listening by checking their schedule online...

An hour ago I was getting the lower 3 down here in NE Victoria just off the whip on all but my Sangean which needs a bit of wire... save the four and just work through them through the day... see what works.

Added bit... now at 1200 local I have the upper three frequencies but 4426 has vanished.