HF in marinas

D

dromio

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I am having difficulty with my icom 801e in marinas. The Rx is not great tho I can hear a bit, but Tx is non-existent ... simply can't seem to be heard. Tried scheds with the set at home (80 40 20) and the signals are very poor. Have just set up a mobile ic7000 set on board with a separate antenna and the results are the same.

Gribs, weatherfax and email are no problem at all (less bandwidth?).

Anyone else use their HFs in marinas? Perhaps it's the proximity of all the other masts?

TIA
D
 
dromio said:
I am having difficulty with my icom 801e in marinas. The Rx is not great tho I can hear a bit, but Tx is non-existent ... simply can't seem to be heard. Tried scheds with the set at home (80 40 20) and the signals are very poor. Have just set up a mobile ic7000 set on board with a separate antenna and the results are the same.

Gribs, weatherfax and email are no problem at all (less bandwidth?).

Anyone else use their HFs in marinas? Perhaps it's the proximity of all the other masts?

TIA
D
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Digital mods seem better, I can get psk31 working and winlink just on some days, but speech is very limited, conditions seem to need to be just right. Anchored is so much better.
 
You are probably right.

I assume you are using a backstay or other vertical antenna.

Your signal will be warming up all the masts in the marina.

Not much you can do about it really except to find somewhere with a bit of space around you and drop the hook.

Or maybe try a "lash-up" inverted V antenna

Longish length of wire - tie the insulated end to the front of the boat, hoist the middle up the mast with a spare halliard and connect the other end to the ATU - or transceiver if it has an integral tuner.

Worth a try for a length of wire and 10 mins work
 
Beadle said:
... try a "lash-up" inverted V antenna ... tie the insulated end to the front of the boat, hoist the middle up the mast with a spare halliard ...
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hmmm ... and avoid spreaders, shrouds etc...

will retreat to my arrl antenna book and peruse the pros and cons of the inverted v. It certainly has its advocates.

D
 
I've only just taken my SRC (VHF) so not familiar with marine H.F. and not sure if you mean that or amateur radio.

If it's the latter I can listen and reply on all the bands you mentioned and am a better than average signal on 80, not bad on 40 and a bit variable on 20. If it's marine H.F. I'll still have listen if that helps.

TX shouldn't be 'non existent' where ever you are, let alone a marina. I say that having had great contacts with bits of wire around, in and thrown out of numerous hotel rooms.

Where are you?
 
Plymouth. Surrounded by masts.

No problem at home or otherwise mobile and I have used HF from several marinas over the years, tho the locations have always been a little different to this one ... more on the edge than surrounded.

ham and marine ... both very poor here.

D
 
dromio said:
hmmm ... and avoid spreaders, shrouds etc...

will retreat to my arrl antenna book and peruse the pros and cons of the inverted v. It certainly has its advocates.

D
Click to expand...

I had an inverted v up for a while before sorting out an insulated backstay. Always hard to be sure with different conditions but if anything the backstay seems better. Steel hull so good ground plane.
 
KellysEye said:
MF/HF transmission never works in marinas because of all the masts around, it needs a clear line of sight. Reception can work to some extent in MF frequencies, That's what we found.
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H.F. does not rely on line of sight. What you are suggesting is a bit like saying people on housing estates will not recevie a good T.V. picture because all thier neighbours have T.V. aerials.
 
Plus, this dicusscusion is pointless until we know what the OP is using as an aerial (and ground?) and what he is trying to achieve. I think.
 
>H.F. does not rely on line of sight.

What evidence do you have to say that. The fact is you can't get a MF/HF signal out with masts around, we found that as did the OP. It has nothing to do with TV aerials they are receivers not transceivers.
 
KellysEye said:
>H.F. does not rely on line of sight.

What evidence do you have to say that.
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The fact that people can talk to each other on HF halfway round the world? Seems pretty conclusive to me. They certainly can't see each other.

I can well believe that a lot of nearby vertical metal poles and wires would interfere with HF radio signals, but that's a separate question.

Pete
 
Dread thrift...

I have used HF for 50 years. There is 1 piece of communication eqpt which will not be on my next boat and this is HF!

However, I will have a proper Satcom and Sat data.

FWIW
 
Beadle said:
No it isn't

You don't normally transmit on your television aerial
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O.K. - perhaps it was a mistake to used the T.V. aerial idea. I was trying to show that having a number of aerials, (or masts, or wires), near to another aerial does not mean a transmission will 'never work'.

The other two statements stand though:

1. H.F. does not rely on line of sight.

2. This discussion is pointless until we know what the OP is using as an aerial (and ground?) and what he is trying to achieve.
 
Moxon said:
O.K. - perhaps it was a mistake to used the T.V. aerial idea. I was trying to show that having a number of aerials, (or masts, or wires), near to another aerial does not mean a transmission will 'never work'.

The other two statements stand though:

1. H.F. does not rely on line of sight.

2. This discussion is pointless until we know what the OP is using as an aerial (and ground?) and what he is trying to achieve.
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OK

Never say never

But the fact is that almost invariably the antenna used on a boat is vertically polarised.

It is also a fact that almost all masts are vertical and electrically conductors.

When you transmit you create a (very rapidly) alternating electrical (and magnetic) field.

This will induce a current into nearby vertical conductors - such as masts, and to a much lesser extent rigging.

This will have two effects - first it will absorb power from the transmitted signal ie it will "heat up" the mast.

Second it will reflect the signal in a direction dependant upon the number of wavelengths separating the mast from the transmitter.

You may liken it to shining a torch through a snowstorm. (the mechanism is different but the effect the same)

The light (signal) is scattered in numerous directions and rapidly loses its strength.
 
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Beadle said:
OK

Never say never

But the fact is that almost invariably the antenna used on a boat is vertically polarised.

It is also a fact that almost all masts are vertical and electrically conductors.

When you transmit you create a (very rapidly) alternating electrical (and magnetic) field.

This will induce a current into nearby vertical conductors - such as masts, and to a much lesser extent rigging.

This will have two effects - first it will absorb power from the transmitted signal ie it will "heat up" the mast.

Second it will reflect the signal in a direction dependant upon the number of wavelengths separating the mast from the transmitter.

You may liken it to shining a torch through a snowstorm. (the mechanism is different but the effect the same)

The light (signal) is scattered in numerous directions and rapidly loses its strength.
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I agree with what you say to a degree. But I can tell you I've used very low power levels to have long distance contacts on H.F. from places far less R.F. friendly than a marina. Which is why we need to know what the OP is using
and trying to achieve when he says that TX is non existent.

But he seems to have gone :-)
 
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i would check your ground wire, it may need better hardware or attachment to keel or whatever your radio is grounded to....bad ground can mean no 'ground plane' which would limit talk output, but allow good receive.
 
Moxon said:
I agree with what you say to a degree. But I can tell you I've used very low power levels to have long distance contacts on H.F. from places far less R.F. friendly than a marina. Which is why we need to know what the OP is using
and trying to achieve when he says that TX is non existent.

But he seems to have gone :-)
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Don't disagree at all

I was seeking to offer an explanation as to why it didn't work - explaining why it DOES work when it seems it shouldn't is much more difficult.

I assumed he was using a vertical - not easy on a boat to use anything else - I did suggest trying an inverted V initially.

I also assumed he had a decent earth - if that is not the case then with a vertical its unlikely to work anywhere - including a marina.

Of course the surroundings can make a difference too. If he's in a harbour surrounded by high ground he'll struggle, or if he isn't correctly matching radio to aerial - numerous possibilities.

Remote diagnostics are never easy - or particularly reliable.
 
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