Handheld VHF - 3 Watt or 5/6Watt?

[Little Rascal]

Can anyone give me an idea of the differences in range between the cheaper 3 Watt and the 5/6 Watt handheld VHF's?

The Cobra MR-HH125 is attractively priced at c£50 but how useful would it be for coastal cruising?

 

[GrumpyOldGit]

In my humble opinion, buy the best you can afford, Icom m71 at 6w output can communicate across Mersea to Brightlingsea ( 7-8nm ) in reasonable conditions !

Smaller will clearly not punch out so far, no doubt expert opinion will tell you more reasons but the little £50 Cobra will not have anything like the range. Good luck anyway. Ps. there was an icom m71 on ebay the other day for about £35. might be worth a look !!!

 

[Phoenix of Hamble]

Second GoG's comment.

Buy a good one. Not only better range, but also survive the knocks better.

I had a cheap Cobra one as a temporary, and it didn't take much abuse before it started to struggle.

 

[pvb]

OK, there's a reason the Cobra's cheap - not waterproof, low output power, NiMH battery.

Spend a bit more and get a proper radio. For £99 you can get a Standard Horizon HX280E, which has 5W output, is submersible, and has a large-capacity Li-Ion battery.

 

[jwilson]

Can anyone give me an idea of the differences in range between the cheaper 3 Watt and the 5/6 Watt handheld VHF's?

The Cobra MR-HH125 is attractively priced at c£50 but how useful would it be for coastal cruising?

I don't think the range will actually be that much different, but I don't think the cheap Cobra has the M1/M2 channels, used by quite a few clubs and marinas. I have two of the next model up Cobras (HH300 and HH325) at under £90 each - one six years old one one year old, and am very pleased with them.

In my experience if you don't get through at 1 watt going to 5 watts doesn't usually help.

 

[davidej]

Simple physics suggests that a 6w transmitter will have 1.4X the range of a 3w one - square law.

 

[Elemental]

Simple physics suggests that a 6w transmitter will have 1.4X the range of a 3w one - square law.

Not quite that simple. VHF Range is usually limited by the VHF horizon not transmission power. A Handheld at 3m above sea level has an horizon of 6Km or so. So for handheld to handleld more power wont help (much) beyond that.

However, if you are talking to the coastguard via a 100m mast to your handheld then your potential range is much greater. Absolute power (!) though, is seldom the range limiting factor.

 

[Elemental]

I too would second the sentiments that you should buy the best you can afford. I'd worry less about the absolute power tho.

 

[LadyInBed]

For £99 you can get a Standard Horizon HX280E.

+1 Good Review and Standard Horizon as a company are well regarded.

 

[pteron]

We were dismasted off Christchurch and I used my handheld to call in the pan pan.

After being towed in to Yarmouth, we popped into the pub that the lifeboat crew frequent and were told that my transmission came in loud and clear for them which was most unusual - they usually only hear the coast guard's side of the conversation.

Icom IC-M71 6W waterproof. Excellent.

 

[Little Rascal]

Thanks for the input.

While it would be nice to "buy the best I can afford" I would say my position is more like: don't pay for what you don't need and then there will be money in the budget for something else

This will be my first VHF and the main (only) radio for the boat - a 19ft trailer sailer so not too ambitious. The SH HX280e and the Ikom's do look good though.

Any views on the Midland Atlantic at c£70-80?

 

[pvb]

Any views on the Midland Atlantic at c£70-80?

Why even consider it when it's so close in price to the Standard Horizon HX280E? The Atlantic is only splashproof - not waterproof and submersible - and it doesn't have a proper battery pack. Surely if it's to be your only VHF, it has to be dependable.

 

[timbartlett]

This will be my first VHF and the main (only) radio for the boat - a 19ft trailer sailer so not too ambitious. The SH HX280e and the Ikom's do look good though.

Hand-held VHF range is usually depressingly short.
Here's why:
Radio horizon. In order for two radios to communicate with each other their antennae (aerials) must both be above each other's horizon. The distance to the horizon depends on the frequency, as well as on the height of the antenna, but for VHF frequencies the distance to the horizon (in miles) is roughly 3x the height of the antenna in metres.
So if the antenna is at 2m, its horizon is about 4.2 miles away
If the antenna is at 9m, it's horizon is 9 miles away
If the antenna is at 100m, its horizon is 30 miles away.
So yacht masthead to coastguard could well be about 40 miles, but handheld to handheld would be about 8 miles.

Power So long as you don't exceed the horizon range, the power limits the range according to the inverse square law. To double the range, you need 4x the power. So if you have a 25W fixed radio comapared with a 6W handheld, thenall other things being equal the fixed set would achieve about twice the range of the hand-held.

Antenna gain Hand-helds generally have antennae that are designed to transmit more or less evenly in all directions, including upwards. Longer antennae generally "focus" thepower towards the horizon. This can typically double, quadruple, or sometimes even octuple the effective power of the transmission if you have a long antenna.

Antenna gain works the other way, too: a good transmitting antenna will be a good receiving antenna. So hand-held to hand-held is not going to be anywhere near as good as hand-held to fixed.

Hand-helds are brilliant for short-range comms, but not much use more than about 5-10 miles. The real cheapies will be struggling at half that -- i.e. they might not reach across the Solent.

For a 19ft trailer-sailer you haven't got much choice, though (a fixed VHF antenna probably isn't very practical!) but something that can withstand water and knocks and still be reliable is.

 

[Phoenix of Hamble]

Just to add to Tim's post to avoid confusion.... Tim meant 3 x the square root of the height in metres.

Tim, knows this, its just obvious that his fingers were working too fast!

 

[Little Rascal]

Thanks Tim and Phoenix.

So you meant 1.41m x 3 = 4.2 miles...

 

[timbartlett]

Just to add to Tim's post to avoid confusion.... Tim meant 3 x the square root of the height in metres.

Tim, knows this, its just obvious that his fingers were working too fast!

Correct.
Thank you and my apologies.

 

[LadyInBed]

This will be my first VHF and the main (only) radio for the boat - a 19ft trailer sailer

As VHF range is partly / mainly governed by the height of the aerial, I would look into fitting a mast head aerial (that unscrews when you take the mast down) and connect it to the H/H.
You don't have to use the mast head aerial all the time, just when you aren't getting through on the H/H's helical.

 

[st599]

Surely you mean the max distance is the sum of the individual radio horizons. Less a bit for Fresnel zone clearance. Rather than they must be within each others horizon.

I was taught that, in electronics and rf, pluralisation is always by adding an s, so radio antennas, computer mouses etc. Is that not common usage? Certainly I've never seen antennae in an engineering context.

 

[barnaclephill]

Cobra HH125

I bought a Cobra HH VHF model MR HH125 for $95 delivered, incl GST/VAT here last week. It arrived Monday.

The reasons for this rather than another model, submersible at 5Watts, etc and bigger AA batteries were:

price competitiveness, as it's only a backup to the main 25W radio in the yacht,

and it's portable, so I can wear it in the cockpit (when the engine's on, it's too noisy to hear everything), and use it in the cockpit on the rare occasion of a converging course with a ship

and I can use it for the dinghy, to keep an ear open if my son goes from the yacht far off in the dinghy. I could also use it when going for a walk on an island, (ie Deal Island) out of VHF range of the main radio with it's 8m mast height. This island is half way between Flinders Is, Tasmania and Wilson's Prom, southern Victoria.

So for those situations, distance/ power isn't the main issue. Being splashproof, care and a plastic bag will be needed to protect it, but for the price...

Having it here all week, I can hear on both 1 Watt and 3 Watt the VHF transmissions from Coast Radio Melbourne, at about 16km away, for weather and safety info. This is the main use of the radio, collision avoidance being less common. I'm on a hill, and I didn't transmit to them.

For a 19 foot yacht, the power requirements might make a HH viable rather than a 25W fixed model. The range doesn't seem to be the most important issue.
And lasty, the aerial on this model is fixed. It doesn't screw off and it's not mentioned in the manual, so screwing in the masthead antenna ain't an option.

 

[timbartlett]

Surely you mean the max distance is the sum of the individual radio horizons. Less a bit for Fresnel zone clearance. Rather than they must be within each others horizon.

I was taught that, in electronics and rf, pluralisation is always by adding an s, so radio antennas, computer mouses etc. Is that not common usage? Certainly I've never seen antennae in an engineering context.

I'm afraid I meant exactly what I said: "In order for two radios to communicate with each other their antennae (aerials) must both be above each other's horizon." ("above" -- not "within")

For comparison, if you are standing with your feet at roughly waterline, then your visible horizon is about 2.5 miles away. I trust we can agree on that? If the light of a lighthouse is above your horizon, that does not mean it is less than 2.5 miles away, does it?

Whilst it would have been more clearly explained with a diagram, I had hoped that the examples I gave would make my meaning clear, eg:
"If the antenna is at 9m, it's horizon is 9 miles away
If the antenna is at 100m, its horizon is 30 miles away.
So yacht masthead to coastguard could well be about 40 miles"

I was taught that the plural of "antenna" was "antennae", but that "antennas" was becoming more and more acceptable (probably in the mid sixties). Although I use the new spelling when I am writing commercially, I much prefer the old -- just as I prefer "esquimaux" to "eskimo". And I'm afraid I actively dislike "mouses", and will continue, unrepentant, to use the word "mice", whatever its context! <insert suitable smiley to show that I am not being argumentative or stroppy, merely disagreeing in a slightly rueful way>