Do i need power?

sirpsycho

I'm having problems getting a good signal from irish stations and no signal at all from english stations. now i know for a fact that people around me with the same aeriel can get all irish/bbc/utv/ch4 etc.

i had a look at what I have(in a new house btw) and here's what I found:

aeriel(big square one)
black box connected between aeriel/tv(assuming this is a booster? (made by prince electronics)

someone told me I might need a power box?

anyone help?

Thanx.

ShaneOC

The black box by the aerial is probably a mast head amplifier. This requires a power supply. If you can trace where the cable enters the house you should see where the previous owners had it. It may be as simple as it was in the attic and the plugged it out when they left.

sirpsycho

the aerial is in the attic, as well as this black box. i cant make out how it is/was connected to a power supply though. there doesn't appear to be any other breaks in the coax apart from where it enters/leaves the black box. any ideas?

watty

Yes the power unit has two coax sockets and inserts the power (often 12V or 9V) to the centre of the coax. Often just behind the TV set.

Two vital parts are used. A coil to block the RF (TV signal) getting "shorted out" by the PSU circuits and a capacitor to block the DC power on coax center pin from TV socket.

I have made these up using a plugtop PSU and a Y splitter with the insides replaced with the 100pF capacitor and 100uH coil. But your local electrical wholsale will sell one. They actualy often sell the mast head amp and power unit separately. The coil can be made of 10 turns of fine enamel wire the diameter of a ball point pen inner (or even wound on an empty) or thick matchstick. The capacitor value is not critical but should be ceramic type for low inductance.



These are mostly compatible between different makes. Ironically a Digbox can power one, but only on its RF out(!) which won't work. The digibox uses the same scheme to power a remote control eye.

byte

You'd want to find out what voltage it requires. It usually states this inside the box beside the connector for cable leading to TV.

Power supplies are usually 12v or 24v (12v seems more common) but whilst a 12v Power supply will work some 24v amps, this isn't always the case, so best to make sure!

I have never seen a Prince amp before.

watty

Yes but he hasn't got the PSU. The mast head amps never state the voltage. 24V is very rare.

A PSU is 1/2 the price anyhow. So buying a replacement PSU and discovering it does not work would waste a lot.


I haven't seen any Prince brand in a long time so buying a new set is probabily best and little more expense.

All you need generally is a small screwdriver, only the very professional amps have Belling lee, F-Connectors (or very rare BNC). Most are one screw for inner wire and a clamp with two screws for the braid.

ShaneOC

Maybe the easiest thing to do is to buy a new masthead amp and power supply. Electrical wholesalers will usually have them. Mine cost about €30 for the two.

byte

Originally posted by watty
The mast head amps never state the voltage.

Most of the amps Ive used do state the recommened voltage either on a sticker or printed on the circuitry itself.

Though yes, most amps use 12V nowadays with the exception of Alcad and few others.

watty

Originally posted by byte
Most of the amps Ive used do state the recommened voltage either on a sticker or printed on the circuitry itself.

Why can't everyone do that, hardly a measurable expense.

byte

Originally posted by watty
Why can't everyone do that, hardly a measurable expense.

LOL, they should I guess! Just a sticker would suffice! That's what Triax use anyway - a sticker across the top giving short detail of what each connector is for.

sirpsycho

Well here are the results...

Got a 12V power unit and all is well now. Crystal clear on most channels apart from Ch4 but it was always the one that didnt come in crystal. Still very watchable though and some days it's almost crystal and there are is never any missing characters from the ch4 teletext. All this from an aeriel in the attic

Thanx for comments by all.