Is length of antenna for MF/HF frequencies (Rx only) important?

[plebian99]

A much simpler way if you using a random length of wire is simply to use a decoupled 9:1 UNUN. Reduces noise and is cheap. When a 9:1 UNUN is connected to a good backstay antenna on receive its a super antenna.

Originally Posted by Robert Tilbury

buy a $2 transistor radio ,,,
If not as i said get an antenna tuner ,, YES for RX ,

There is no other way unless you want to get a piece of wite at the exact resonace of the frequencey you want to listen to ,, then trim(YES TRIM) it to the new frequency ,,

Or you could get an antenna tuner (yes again) to TRIM the antenna for you ,,,

ITS called resonance ,,
Google it ,,,
Its basic electronics ,
RX TX it dont matter ,,,,,,,,

[Robert Tilbury]

Originally Posted by plebian99

A much simpler way if you using a random length of wire is simply to use a decoupled 9:1 UNUN. Reduces noise and is cheap. When a 9:1 UNUN is connected to a good backstay antenna on receive its a super antenna.

agree 100% but then we need a 145 page detailed paper on what an "UNUN "
Then the confusion with a "BALUN"

then next (and this would be great )

They would all get there HAM licence ,

Cheers
73`s
VK2LOZ

[Rorzech]

This radial you run from bow to stern. Are the ends connected to fore stay and back stay ?

[hellosailor]

Nomad-
The inexpensive SDR radios are certainly cheap enough to gamble with. But I've heard that the sdrPlay that Nicor mentioned was "as good as a real radio". That was the first model, I think now reduced to $100 because it is superceded by " a really damn fine radio" the sdrPlay model 2 at around $200. I've heard the new model is quite comparable to dedicated receivers, and it allows the use of multiple antennas so that you can compare two different antennas, or use different antennas on different bands, just by clicking your keyboard.
As always there are YouTubes on it. Looking like a very much worthwhile option. (There's one called Lime-something that gets even more raves, but that's $1000 territory and does way more than just sdr.)

[knockabout]

most older HF/MF sets you can take the mic off connect a piece of coax to the set then connect the centre wire of the other end of the coax to backstay/capping shroud/or any shroud and they will receive / through an antenna tuner to fine tune weaker signals helps but they do receive stronger signals well without too much fuss / don't hit the transmit button / that includes built in antenna tuners that tune on TX when you hit the button / you need proper length antennas for those

[Robert Tilbury]

On the ham radio sites you can pick up a real HF radio ,, look for the ones that have blown finals ,, (They dont transmit )
But what you get is a profesional readio with AM , LSB,USB,FM and CW
On top of that you get a clarifier , Notch with the best selectivity and sensitivity you wont get on a SDR ,

I picked up a ICOM IC738 with blown final transistors for $75 ,,,
Fantastic rig ,
I replaced the finals ,(purchased from flebay for $30)

when the propogation is right i recieve world wide ,

I have never had any luck with SDR`s i just think the reciever module is $5 worth of electronics wedged int a small can ,,,

Do it right ,<(still can do it cheap)
But there is so much good quality gear out there ,

[Robert Tilbury]

Originally Posted by knockabout

most older HF/MF sets you can take the mic off connect a piece of coax to the set then connect the centre wire of the other end of the coax to backstay/capping shroud/or any shroud and they will receive / through an antenna tuner to fine tune weaker signals helps but they do receive stronger signals well without too much fuss / don't hit the transmit button / that includes built in antenna tuners that tune on TX when you hit the button / you need proper length antennas for those

My ic738 there is a menu so you can turn the "Tune" and "transmit" buttons of so no woops ! ,

I have seen transievers on the
"QRZ" forum for under $100 fully working ,,
Most with post in the US for $20 ,,
Worth a go in my mind .

[El Pinguino]

Its very easy to overthink some stuff....

My view....

I would simply buy a Tecsun 680 from a reputable dealer such as Anon-co on Ebay... https://www.ebay.com.au/itm/TECSUN-P...AAAOSwstxVPe6H
or if you are ' in funds ' spring for the 880.

Both excellent radios for SSB and general shortwave work. Plenty of reviews out there. On passage in temperate climates ( dream on Pingo!... ) I will often have one under the dodger at night tuned into RNZI on just the whip.

Plenty of reviews of these radios out there .

Both work good either on the whip or with the 'long wire' that is included.. same same this one https://www.ebay.com.au/itm/EB-Hot-T...wAAOSwu4BVr1ZN

First pic.... just received on my 880 using the AN-06 wire... conditions are somewhere south of shocking just now... this usually works well.

Second pic.... also today...same radio 880 hooked up to something fancier... one of these - https://www.gwhip.co.uk/receive-only-antenna

I use cocoamodem2 cocoaModem on a Macbook Pro feeding the signal in through one of these... https://www.ebay.com.au/itm/Sabrent-...4AAOSwT6pVo7Dh

KISS.. keep it simple, sailor!

[conachair]

Originally Posted by settlednomad

As I am a belt and braces man - and I like to experiment with things - I think an inexpensive dongle has to be worth a bash.

Fantastic fun to have a play with but for being useful on a boat unfortunately they don't go low enough to receive weatherfax - something very high up the list for a long distance boat IMHO.

Lots of "my radio is best" out there This is mine
No need for a tuner.

Degen DE1103 Product Reviews

[Cpt Pat]

If you ever want to see an endless debate, find a message thread where Radio Amateurs debate antenna designs. I'm an Amateur "Extra" operator (N8QH) and I designed antennas for a living for some years (HyGain Electronics). The reason for all the debate is this: most antennas are less-than-optimal but still work just fine. Unless you are designing an antenna for one specific application to operate at one specific frequency, such as for a broadcast station (I was also a broadcast transmitter engineer), you will never achieve an optimal design. So don't fret over it. I've heard people claim that a bent coat hanger worked at 160 meters - and if it worked for them - then they are right.


The post above that says a good transmitting antenna makes a good receiving antenna, is spot on. It's called the "transmission/reception reciprocity theorem." But since you only need a receiving antenna, you don't need the complexity and robustness of a transmitting antenna. An antenna tuner would help, but you don't need to worry about reflected power. You don't need heavy gauge wire, or even coax cable.


To answer your question about antenna length: the most efficient non-directional antenna (I can't imagine why you'd want a directional antenna) is a 1/4 wavelength vertical antenna with at least a 1/4 wavelength horizontal ground plane. But you will probably want to use that antenna on multiple wavelengths. So... there is no "correct" length. Those of us who need to transmit have to avoid lengths that are multiples of 1/2 wave because a 1/2 wave antenna cannot be coupled through an antenna tuner (it has infinite impedance). But that too is not a problem for you to worry about.


I encourage you to simply experiment. Since you aren't transmitting, you won't damage anything. I've seen people hoist a wire antenna in the rigging, or run it along the mainsail leech - but if your topping lift is wire it will "couple" and degrade performance. I've seen people put insulators on their topping lift ends and use that as an antenna while using the boom as a ground plane. I've seen people fly a wire antenna with a kite (stay away from power lines!). The kite idea has the merit of allowing adjustment of the antenna length to the frequency. I personally use a delta loop antenna that utilizes my entire rig (A Simple Delta Loop Antenna for Smaller Vessels). I don't claim it's "optimal", but it works quite well.


Your ground plane is just as important as your antenna. Unless your boat has a steel hull, you will probably need to improve it. Start by using your DC negative bus as "ground." I personally trail a 50 foot stainless steel flat braided strap "ground" off the stern that's electrically connected to my DC negative bus and wire standing rigging when I need real performance (and during thunder storms). You can get that from American Grounding Systems (Ground straps and braids, ropes & wires by AGS. Online Catalog and Custom Design- SAMPLE REQUEST -tinned and bare copper, nickel plated copper, stainless steel, braided ground straps).


I suggest just trying something that's mechanically convenient and then tuning around to see if it works. Maybe use a clip lead and just start clipping it around. Try the shrouds and stays for starters. There is an excellent set of "beacon" transmitters on 2.5, 5, 10, 15, and 20 MHz: WWV and WWVH. If you hear a male voice announcing each minute - you are receiving Colorado / a female voice is Hawaii.


Finally, a point made above deserves more comment: interference will be your worst enemy. It'll make weather faxes look like trash. Once you have good reception, I suggest turning on any LED lights you have - one at a time. If you are very lucky, one on more of your LEDs won't wipe out the entire HF band (and maybe VHF as well). Radio Amateurs are finding the HF band to be practically useable from November through early January. The reason: LED Christmas lights.

[s/v Jedi]

There’s no way around it... you’ll have to start with morse code at 8wpm, then go from there [emoji23]

[SoonerSailor]

Bravo, Cpt Pat!

[conachair]

Originally Posted by Cpt Pat

Finally, a point made above deserves more comment: interference will be your worst enemy. It'll make weather faxes look like trash. Once you have good reception, I suggest turning on any LED lights you have - one at a time. If you are very lucky, one on more of your LEDs won't wipe out the entire HF band (and maybe VHF as well).

Tracking interference down is enough a reason to get a cheap RTL dongle alone

https://www.rtl-sdr.com/spektrum-new...yzer-software/

[Jim Cate]

Originally Posted by conachair

Tracking interference down is enough a reason to get a cheap RTL dongle alone

https://www.rtl-sdr.com/spektrum-new...yzer-software/

But if it does not receive the frequencies upon which you wish to operate (as has been claimed upthread, then it isn't much help. Lots of forms of RFI are not broad band.

Jim

[conachair]

Originally Posted by Jim Cate

But if it does not receive the frequencies upon which you wish to operate (as has been claimed upthread, then it isn't much help. Lots of forms of RFI are not broad band.

Jim

Very true, but will still show if an LED is very naughty, if it's naughty up top good chance it will be naughty further down.

Anyway, dongle costs less than a beer in London so no real reason not to have one.