MASTHEAD AMP FOR CLAREMORRIS TUAM AREA

firemansam1

Hi,

What would generally be a good masthead amp for the Claremorris/Tuam and in between area for receiving from Castlebar direction. What i'm asj=king is what gain should generally suffice around there.


Want to get RTE's and BBC's etc etc. I'm using a grid aerial and also a contract pointed to Maghera or Truskmore for TV3. Seems to be the done thing around here.

Thanks

watty

you need a dish and Freesat receiver, ideally Freesat HD (even if you have no HDTV) for BBC & ITV.

firemansam1

watty wrote: »

you need a dish and Freesat receiver, ideally Freesat HD (even if you have no HDTV) for BBC & ITV.

No, I'm using aerials as they have sky already on one TV. I want something that I can distribute to other rooms. RTE analogue will be fine from Castlebar for another couple of years yeah????

And TV3 from Maghera too?????????

That swhat they want.

What gain amp should suffice.

Sponge Bob

UHF band a and UHF band b both need amping so.

firemansam1

Give me a rough idea of what gain amp I would need roughly!!!!

Galway

firemansam1 wrote: »

Give me a rough idea of what gain amp I would need roughly!!!!

I suggest you use a Johansson masthead amp 7451. It has two separate variable gain (25-40 db) UHF inputs grouped as follows - input 1 - channels 21-38, input 2 channels 42-69. This eliminates the need for a combiner, as you connect the Cbar aerial (channels 23 (TG4) , 29 (RTE 1) , 33 (RTE 2) to input 1 and the Maghera UHF aerial (channels 66 (TV3) & 68 (TG4)) to input 2

The amp also has a variable gain input (10-30db) for VHF band 3 and another for FM radio (88-108 Mhz), fixed gain of 12db. You probably wont be using these and you can put plastic caps over these inputs. You will also need a Johansson 24 volt power supply, available in single (part no 2431) and dual outputs (2430). If you are feeding more than 2 tvs set you will need a distrbution amps. Make sure you get the proper 24V PS as if you use a 12V one you will experience some signal loss. The beauty of the 7451 amp is that you it has 2 separate grouped UHF inputs and variable gain on both. Hope this helps!

firemansam1

Thanks for that,

so I'd need that much gain yeah. Sounds like a good amp....where can i buy???

I didn't realise that that much gain would be required. I have an interest in this stuff but don't do too many...not for a living or anything.

watty

Gain is only for driving cable loss. The important thing is the aerial

You then adjust gain only to cancel the loss of cable or else you amplify noise.

firemansam1

Well the run of cable from the aerial will be going about 10M to a sky box and then back up to the attic to distribute to 2 mor TV's, should I use a dist. amp too.

Watty, do you reckon I need 20db + gain

watty

No
About 6dB to 12dB

If it's not good enough then you need better aerial.

firemansam1

I have a TRIAX/WOLSLEY Grid Aerial and a contract group C/D. Most houses around the one I'm doin have grids so I would assume(I know i shouldn't but...!!!!).

I have a 7-22dB variable gain amp(proception)

watty

proception are good.

firemansam1

watty wrote: »

proception are good.

what about the aerials

Galway

You can vary the gain from 25 to 40 db, as I said the gain is adjustable. You WILL need 25 or so to get clean pictures from Maghera on a contract at your location. As long as the signal is clean prior to amplification, you should be ok, otherwise you just amplify the grainyness which is known as 'noise' The extra bit of gain and ability to adjust it is useful if you are connecting 2 or more sets. The grid isnt the best for Cbar as its channels are in UHF group A (channels 21-37) where wideband aerials always perform worse. I suggest you replace the grid with a Triax Supergain 18 group A and and the contract C/D with a triax Supergain 18 Group C/D ,which should improve your basic signal prior to amplification. Also, as these aerials have a balun, which your existing ones I suspect, dont, you will be digital ready for the Autumn.

firemansam1

The grid will be pointed to Castlebar, contract C/D to Maghera

Galway

firemansam1 wrote: »

The grid will be pointed to Castlebar, contract C/D to Maghera

I understood that. I was merely suggesting aerials that would perform better than those you have that would improve your initial signal prior to amplification to minimise the noise figure. You asked about the aerials in previous post.

firemansam1

Galway wrote: »

I understood that. I was merely suggesting aerials that would perform better than those you have that would improve your initial signal prior to amplification to minimise the noise figure. You asked about the aerials in previous post.

Sorry, yeah I see where you are coming from all right. Alas, as the aerials are got now, i will use them as they seem to be used all around this area.

The contract aerial which will be pointed Maghera has a balun so that should be ok for DTT. Am I right.

Thanks Galway

Galway

firemansam1 wrote: »

Sorry, yeah I see where you are coming from all right. Alas, as the aerials are got now, i will use them as they seem to be used all around this area.

The contract aerial which will be pointed Maghera has a balun so that should be ok for DTT. Am I right.

Thanks Galway

You are. The DTT is active currently from Maghera on channel 48. It is mooted that DTT from Cbar will be on air by the autumn.

watty

ALL yagi or grid should have a "balun", nothing to do with Analogue vs digital.

It's just that good aerials (even in 1960s) use a balun and rubbish ones don't.

Galway

watty wrote: »

ALL yagi or grid should have a "balun", nothing to do with Analogue vs digital.

It's just that good aerials (even in 1960s) use a balun and rubbish ones don't.

Plenty that are up pre DTT have no balun at all - esp grids and contracts!

watty

if they work on Analogue they will work on Digital.

Baluns are just part of good aerial design. There is no such thing as a Digital or Analogue cable or design of aerial.

Galway

watty wrote: »

if they work on Analogue they will work on Digital.

Baluns are just part of good aerial design. There is no such thing as a Digital or Analogue cable or design of aerial.

Er, I dont recollect saying that there is a digital or analogue aerial. I am well aware that the aerial will pick up the signals regardless if they are analogue or digital. While baluns are not new, they are recommended for DTT installations.

watty

They are equally recommended for Analogue. There is no greater or lesser need in either case.

Yagi and Grid aerials unless they are constructed with "Gamma Match" (and none I have seen for domestic use are), are inherently "Balanced" and always will be and always have been.
Ribbon cable is inherently "Balanced" and always will be and always has been.
Coax cable is inherently "Unbalanced" and always will be and always has been.

A Balun converts between the two. It was equally important to have a balun in 1972 as it will be in 2020. Digital is irrelevant. I have a good condition 1985 yagi aerial and it has a balun because it was good quality and not cheap rubbish. I have an Aluminium 1992 "grid" or 4 x bow tie that has a Balun. Cheap rubbish copies are made of coat hanger wire and have no balun.

You need a Balun, because coax on an Yagi or Grid needs a Balun. Not because "they are recommended for DTT installations". They are recommended for Yagi, dipole or Grid array aerials, period. Always have been, since coax invented.

Galway

watty wrote: »

They are equally recommended for Analogue. There is no greater or lesser need in either case.

Yagi and Grid aerials unless they are constructed with "Gamma Match" (and none I have seen for domestic use are), are inherently "Balanced" and always will be and always have been.
Ribbon cable is inherently "Balanced" and always will be and always has been.
Coax cable is inherently "Unbalanced" and always will be and always has been.

A Balun converts between the two. It was equally important to have a balun in 1972 as it will be in 2020. Digital is irrelevant. I have a good condition 1985 yagi aerial and it has a balun because it was good quality and not cheap rubbish. I have an Aluminium 1992 "grid" or 4 x bow tie that has a Balun. Cheap rubbish copies are made of coat hanger wire and have no balun.

You need a Balun, because coax on an Yagi or Grid needs a Balun. Not because "they are recommended for DTT installations". They are recommended for Yagi, dipole or Grid array aerials, period. Always have been, since coax invented.

Ok.. lets get big skip for all those without baluns so...

rockey1

firemansam1 wrote: »

The grid will be pointed to Castlebar, contract C/D to Maghera

firemansam1 you can buy a amp here http://www.digitaltvdonegal.com/products.html the one you will want is a 25W Masthead Amplifier price 25euro this one is really good you can turn the gain up and down till you get it just right any thing more than 25 is no good all you do is boots the snowey picture this should do you

firemansam1

Thanks Rockey1, but I already have a variable gain amp 7-22dB so that should be nearly as good as the one you mention shouldn't it.

Thanks

firemansam1

Well, job done, the grid, contract C/D and the variable gain amp worked a treat.

Amp turned up about half way or a little less and perfect picture on 8 channels.

Thanks for all the advice.

Tactical

Galway wrote: »

Ok.. lets get big skip for all those without baluns so...

So can anyone recommend some manufacturers of good quality aerials with a balun as standard?

watty

Blake Aerials
http://www.blake-uk.com/page/home

Also Triax, Kathrien

Tactical

Excellent. Many thanks

championc

Who in Dublin stocks these Johansson masthead amps / combiners ? Are there any spec sheets online to see a list of the various models available ? I've had a search and only found a link to an Australian site and there was no sign of a 7451 amp.

EDIT: Found http://www.Johansson.be


C

watty

Try Proception from http://www.blake-uk.com/page/home
Also ring Polytron in Bandon

I've used polytron channel filter/combiners

David Della Rocco

championc wrote: »

Who in Dublin stocks these Johansson masthead amps / combiners ? Are there any spec sheets online to see a list of the various models available ? I've had a search and only found a link to an Australian site and there was no sign of a 7451 amp.

EDIT: Found http://www.Johansson.be


C

http://mcgrathelectronics.ie/manufacturers/

This crowd are in Dublin, not sure if they are trade only though.