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#1 Denis R

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Posted 28 August 2006 - 07:24 PM

I've got one of those Omnimax 'egg whisk' TV antennas on a 10ft pole at the front of the boat feeding through an Omnimax 21dB amplifier. No matter where I am the picture's crap, sometimes it's crappier than others, sometimes reasonable but never really crisp. To add insult to injury, last night I was walking past a line of moored boats at Napton and everyone had a cracking picture - even those with the pesky egg whisk sat on the roof. Mine was still crap.....
The 21dB amplifier's gain adjust doesn't seem to do anything. Doesn't matter how many times you turn it in either direction, through the 'click' or not, it doesn't make any difference.
Anybody got any tips for getting this system to work before I chuck it away in disgust and try something else?
The TV's a 240 volt LCD, but I can't imagine the TV would affect it?
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#2 Yoda

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Posted 28 August 2006 - 07:38 PM

I've got one of those Omnimax 'egg whisk' TV antennas on a 10ft pole at the front of the boat feeding through an Omnimax 21dB amplifier. No matter where I am the picture's crap, sometimes it's crappier than others, sometimes reasonable but never really crisp. To add insult to injury, last night I was walking past a line of moored boats at Napton and everyone had a cracking picture - even those with the pesky egg whisk sat on the roof. Mine was still crap.....
The 21dB amplifier's gain adjust doesn't seem to do anything. Doesn't matter how many times you turn it in either direction, through the 'click' or not, it doesn't make any difference.
Anybody got any tips for getting this system to work before I chuck it away in disgust and try something else?
The TV's a 240 volt LCD, but I can't imagine the TV would affect it?


There are several things to try before getting rough with it. I understand that it is all new.

You need to maintain a 75 ohm impedence to enjoy a good signal and this means making sure that the inner core of the cable is not touching the outer wires.
The amplifier supplies 12 volts or so to the mast head amplifier is this working.
Have you grounded the support pole to the boat.

Check all the cabling first making sure nothing is loose. Also check for any corrosion in plugs.
Do you have the TV tuned to the correct band for local viewing
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#3 Denis R

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Posted 28 August 2006 - 08:48 PM

Hi Yoda,
It's a new installation. Checking all the cables with my multimeter shows no shorts. The co-ax feeding the masthead is reading about 9 volts. The aluminium pole is grounded to the boat roof through the mounting socket. The masthead is isolated from the pole via its plastic body. All the connections seem to have been well made. (The electro-mechanical guy at the boat builder has a pretty damn good standard of workmanship). The TV will auto tune through its full range and finde about three positions for each channel, varying from mediocre to abysmal.... Had fun checking that lot this evening!

Oh, I forgot - the array on the masthead shows continuity with the shielding on the co-ax....
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#4 dor

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Posted 28 August 2006 - 09:15 PM

Yes I've got an Omnimax. I get a perfect picture in most places, and I don't even put in on the roof; most of the time I just prop it up in the cratch.

I use it with a booster, Don't know what make, just a standard little booster - not the matched Omnimax.

I like the Omnimax as it doesn't matter where you are - I just flick through the channels until I find a decent picture - as my normal cruising area can be in one of three different regions - with the Omnimax I don't have to work out where I am and which fdirection to point the aerial.

I would suggest that the problems you are having are to do with your setup - not because you are using an Omnimax.
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#5 hnb2907

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Posted 28 August 2006 - 09:31 PM

I've got one of those Omnimax 'egg whisk' TV antennas on a 10ft pole at the front of the boat feeding through an Omnimax 21dB amplifier. No matter where I am the picture's crap, sometimes it's crappier than others, sometimes reasonable but never really crisp. To add insult to injury, last night I was walking past a line of moored boats at Napton and everyone had a cracking picture - even those with the pesky egg whisk sat on the roof. Mine was still crap.....
The 21dB amplifier's gain adjust doesn't seem to do anything. Doesn't matter how many times you turn it in either direction, through the 'click' or not, it doesn't make any difference.
Anybody got any tips for getting this system to work before I chuck it away in disgust and try something else?
The TV's a 240 volt LCD, but I can't imagine the TV would affect it?

Hi,

I had one of these on our previous boat, and the picture quality generally ranged from cronic to crap. About the only place we could ever get a good signal on all 4 channels was on Bosley aquaduct.

Another tip - if you've got the booster/amplifier box with a knob that goes round and round for ages. Try turning it back a few turns from the highest setting. If you're somewhere where the signal is ropey, sometimes it amplifies too much of the crud and makes the picture worse or messes up the frame triggering.

I used to turn it to about 1/2 way, then turn it up until the picture cleared and stopped before the picture then went worse as the noise got amplified too much.

Everyone above has mentioned the other things to check - decent connections/cabling and impedance matching, no shorts or stray bits of the copper braiding loose in the plugs/sockets (if you've made your own)...

Got to say, I wouldn't fit one when we did our new boat. I've got a sat dish, and it probably gets used 1 or 2 times a year. Conversing with the ducks is generally far more entertaining and enlightening than watching big brother or the doom/gloom of the 10pm news ;o) Each to their own though!


Cheers,
Chris.
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#6 alan_fincher

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Posted 29 August 2006 - 11:29 AM

I'd say that if the little red LED is lighting up on the antenna itself, then it's pretty likely correctly cabled, as that's how it gets it's power supply, and if there were either a break or short in the cable between antenna and amplifier, I don't think the LED could come on.

However, I'm highly suspicious though that you say changing the gain on the amplifier makes no difference, as it certainly does on ours.

Ours is an elderly one that came with the boat, and does not work that well, although is much improved by putting it 5 feet into the air on a pole, rather than just on the cabin top.

I don't know if they have improved them since ours was made, (quite likely, I guess, even if all are externally similar), but don't feel too inclined to make the considerable spend on a new one to find out.

We are on the southern Grand Union mostly, which I think is fairly infamous in many places for poor picture quality. It may be that nothing short of a high gain aerial on a 20 foot pole works well in many of the locations around here. (There are lots of people with fairly extreme arrangements, leading me to think that any simple omni-directional aerial is unlikely to give very good results at these locations).

We have more success with Free to Air Satellite, on the whole. It works well, as long as the dish can 'see' the satellite, and that's what we now tend to use.

Alan
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#7 Yoda

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Posted 29 August 2006 - 12:26 PM

Hi Yoda,


Oh, I forgot - the array on the masthead shows continuity with the shielding on the co-ax....


What do you mean, some of it must be isolated otherwise you won't have a proper signal
Recheck your work. The centre of the coax must go to a seperate part of the antenna, with all of the rest to ground.
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#8 Denis R

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Posted 29 August 2006 - 05:52 PM

I've re-checked the co-ax feeding to the antenna head from the amplifier and it's fine - no shorts. However, all the 'eggbeater' array of wire is connected to the threaded outer section of the connector on the antenna head. The centre post shows no continuity with the wire array. On my antenna, there's no LED indicator. I can't get inside the antenna head to work out what's in there....
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#9 Yoda

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Posted 29 August 2006 - 06:32 PM

I've re-checked the co-ax feeding to the antenna head from the amplifier and it's fine - no shorts. However, all the 'eggbeater' array of wire is connected to the threaded outer section of the connector on the antenna head. The centre post shows no continuity with the wire array. On my antenna, there's no LED indicator. I can't get inside the antenna head to work out what's in there....


The centre core wire should not be connected to the outer array at any time. The outer wires should be at the same potential as the outer array. Is the inner wire long enough to touch the core of the socket? Try bending the inner wire slightly in the plug to make better contact.

Due you have a long length of cable from the amplifier to the TV? Is it coiled up?
Is the amplifier close to the antenna or the TV ie is it trying to amplify a poor signal to start with?

If you cannot find anything at all wrong, then remove the antenna from the pole and put it on a wood pole to isolate it from any metal. Does this make any difference?

When you move the boat both locally from exactly where you are or as your cruising, make any difference to the signal.

Please get back to me on this problem.
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#10 alan_fincher

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Posted 29 August 2006 - 07:19 PM

Yoda,

The mounting on these antennas is entirely plastic.

If you put them on top of a pole, then there is no electrical contact between pole and antenna. (The cable and 'F' plug will probably be passed though the pole, but the metal outer of the 'F' plug can't touch the pole, normally - there is a significant gap, and unless braiding were poking out a very long way, I don't think it could happen).

Denis,

Can you confirm you have a little red LED light on the antenna, and that this comes on correctly when the amplifier is switched on ?

If it does, my very strong thought is that the two are correctly wired together.

Only if the LED isn't lighting, would I concentrate first on the cabling.

If it is, and the amplifier makes no difference, I'd suspect either a fault in the box inside the boat, or whatever electonics are inside the plastic mount of the 'egg beater'.

(Clearly both bits must contain electonic components, or there would be no point in the antenna itself being powered....)

Alan
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#11 Yoda

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Posted 29 August 2006 - 07:24 PM

Yoda,

The mounting on these antennas is entirely plastic.

If you put them on top of a pole, then there is no electrical contact between pole and antenna. (The cable and 'F' plug will probably be passed though the pole, but the metal outer of the 'F' plug can't touch the pole, normally - there is a significant gap, and unless braiding were poking out a very long way, I don't think it could happen).

Denis,

Can you confirm you have a little red LED light on the antenna, and that this comes on correctly when the amplifier is switched on ?

If it does, my very strong thought is that the two are correctly wired together.

Only if the LED isn't lighting, would I concentrate first on the cabling.

If it is, and the amplifier makes no difference, I'd suspect either a fault in the box inside the boat, or whatever electonics are inside the plastic mount of the 'egg beater'.

(Clearly both bits must contain electonic components, or there would be no point in the antenna itself being powered....)

Alan


I agree but that was what I was working up to as a failure of the mast head amplifier can only be established once every other thing has been checked. The very fact that twiddling with the amp gain has made no difference leads me to think that there is very little signal available from the masthead.
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#12 Denis R

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Posted 29 August 2006 - 08:19 PM

Well chaps, thanks for your input, but I have to announce myself totally scunnered. The antenna unit doesn't have an LED. The cable run is short and direct. Amplifier to connection box for the aerial on the outside of front bulkhead and amplifier direct to TV connection socket in the cabin. Red LED on the amplifier is lit. There is no excess shielding that could cause a short and the various connectors have been made off well. The picture does improve if I move out of my mooring and into open territory, but at no time is the picture what I would class as 'good'. It's viewable down on Puddle Banks but not really crisp and sharp, still somewhat grainy..... And as I mentioned before, at Napton over the weekend everybody else seemed to have a cracking picture without the benefit of a mast, mine was lousy....
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#13 David

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Posted 29 August 2006 - 08:51 PM

Suggest you get an ordinary house arial, Halfords cheap as chips, wack that direct into the TV. Most places it just needs to be lying on the roof, no pole needed.
Thats what I did after disconecting the Onimax amplifier (already fitted when we got the boat) and chucking it and the also usless arial in the shed.
Anybody want to buy it ?
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#14 Yoda

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Posted 29 August 2006 - 09:06 PM

Suggest you get an ordinary house arial, Halfords cheap as chips, wack that direct into the TV. Most places it just needs to be lying on the roof, no pole needed.
Thats what I did after disconecting the Onimax amplifier (already fitted when we got the boat) and chucking it and the also usless arial in the shed.
Anybody want to buy it ?
david


Did you get a class A or B antenna? ie was it flat or vertical or a cross. If you dont have a universal arial, the signal can be 30 dB down and you will still think you have a problem. I think we are going into what is termed as luck!!!

I suspect that the mast head amp has blown. The reason for this is that the unit is new and probably went on switch on. If it survived more than 5 minutes, it will last forever. Take it back.
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#15 alan_fincher

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Posted 29 August 2006 - 09:13 PM

The antenna unit doesn't have an LED.


Perhaps they are not all the same then, despite sharing the 'Omnimax' name then, Denis ?

Here's an extract from my elderly instructions

If you look at stage 7 of Trial assembly, you can see where at least some of them should light up on the antenna head itself.

If you have the piece of transluscent red plastic there, (quite small), but it doesn't light when your internal amplifier is switched on, then I'd say it isn't amplifying at all.

Does your kit of bits look like what's pictured in 1), or are we talking about a different antenna ?

Finally note point 10 - it can take a full 6 turns of the gain knob to reach maximum gain.......

Posted Image

Edited by alan_fincher, 29 August 2006 - 09:29 PM.

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#16 Denis R

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Posted 29 August 2006 - 09:32 PM

Funny you should say that Yoda. This is the second installation and has been fitted under warranty. Right from new the first one would pull down the LED on the amplifier everytime you plugged the lead into the TV.... Midland C's said they'd never heard of that happening before and handed over a new amplifier and antenna complete. At least the LED stays lit now and there is some semblance of a picture.... I've had another go at twiddling the gain up and down and it seems to be making a slight difference - the ghosting decreases with increasing gain, but you can't get shot of it completely. I've just done an auto scan of the channels and it's found them OK. Fine tuning doesn't improve the picture quality at all.

Hi Alan,
Mine is an Omnimax Maxview. The instructions are the same as yours... except my instructions have no step 7. My step 7 is your step 8....
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#17 alan_fincher

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Posted 29 August 2006 - 09:36 PM

Denis,

An apology on one point....

On re-reading the thread, I can see you had already said that your antenna didn't have a red LED, before I kept asking if it did ......

Doh !

I do find it strange if they have engineered this out though. It was presumably included on models such as mine so you could easily confirm that the antenna unit is receiving power.

At the very least, if they no longer have it, diagnosis is harder....

[EDIT]

Sorry seem to be cross posting with you....

I've removed a question I just asked about your instructions, as you answered it while I was asking it....

Removing this daignostic tool, (presumably so they can make them cheaper ?), hardly sounds like progress to me.

As yours ain't like mine, I'll dip out - sorry if I've added any confusion rather than helped !!
Alan

Edited by alan_fincher, 29 August 2006 - 09:39 PM.

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#18 Denis R

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Posted 29 August 2006 - 09:50 PM

I think I'll take a run up the cut tomorrow evening and see if I can engineer a decent picture out on Puddle Banks. I'll repeat the tuning process and play with the gain and see what it's like. I'll not be holding my breath.... Thanks for the input all. I think what I've got is what I'll get.....
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#19 Yoda

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Posted 29 August 2006 - 10:13 PM

I think I'll take a run up the cut tomorrow evening and see if I can engineer a decent picture out on Puddle Banks. I'll repeat the tuning process and play with the gain and see what it's like. I'll not be holding my breath.... Thanks for the input all. I think what I've got is what I'll get.....


Dennis, get someone to chug up the cut for you as you fiddle with the system.

Do check everything first ensuring that the installation is correct then chug and fiddle stopping where required to get a good signal. Tune the TV to the strongest signal and go from there. Another thing you can do is take the amp out of the line and go straight to the TV. If the signal improves the mast head amp has gone.

It is possible to have a faulty batch of product that you are trying to fix.

Set the amp gain at half way ie 3 turns and leave it.

Good luck and let us know the outcome.
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#20 alan_fincher

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Posted 30 August 2006 - 06:52 AM

Set the amp gain at half way ie 3 turns and leave it.

Mine only works at more or less full gain.

Unless it was a very very good signal area, setting it half way would give me virtually no picture at all.....
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