I need an IN-LINE 6db ATTENUATOR

mike65

Anyone know where I can get one without being taken to the cleaners?

This type

http://www.zintek.ie/aerials/installation-accessories/philex-6db-inline-attenuator.html 17 euro including delivery.

watty

For Sat or TV?

6dB is a strange figure unless you are equalising levels at TV head end combiner.

Polytron co. Cork, CPC, RS, Satellite.ie ?

With Sat you can have problem with unreliable tone switching unless it's specially for Sat IF cable.

snaps

http://www.ebay.ie/itm/Philex-VHF-UHF-6dB-Fixed-in-line-Metal-Attenuator-Coax-plug-to-socket-/330742050899?pt=UK_Sound_Vision_Other&hash=item4d01c33053

Antenna

If its for terrestrial, a cheap resistive Y-splitter will give you a drop of 6dB on each output. Both outputs should be connected to something (TV/STB etc).
Don't attempt to use it for satellite..

BTW A 6dB drop means you will be getting only a quarter of the signal power before the drop.

watty wrote: »

6dB is a strange figure

Its been recommended by others here to insert a 6dB attenuator at installation to see if a DTT reception has good clearance of the 'digital cliff' - if reception still works (or starts to have only very slight breakup problems) - there is. Obviously remove it after the test (unless there is the very unlikely senario of too much signal causing problems and to be left there all the time!).

mike65

Its for Satellite cable, got a strange issue with BBC HD channels (them only) would like to see if it works.

That ebay design looks wrong for an F-connector fitting.

watty

The Philex one won't work for Sat IF.

Put a damp cloth over the LNBF front. I absolutely disbelieve an issue with BBC HD on satellite is solved with an in-line attenuator!

As well as a damp cloth, I have used a piece of Aluminium foil with small hole. Why? Same reason as an attenuator on Digital TV aerial. To see rain margin and make fine tuning alignment on TV setbox meter more accurate.

The output of an LNBF is huge. The main part of the Receiver inside a TV on Terrestrial UHF is inside the LNBF.

A suitable length of coax will give you 6dB loss about x4 shorter than 6dB on UHF TV.

If you google you'll see the dB loss per metre at desired IF frequency between 950 MHz and 2100MHz for the cable type you have. 6dB at say 1200MHz isn't hard to achieve!

I'd use a 12dB attenuator to check digital terrestrial TV if I was using that method. But it's misleading as any noise is ALSO attenuated by 6dB or 12dB. So if noise is local and RF path long and weather bad you can "pass" a 12dB good Weather test and still lose signal.

Really there is no substitute for a meter with BER and spectrum.

STB

mike65 wrote: »

Its for Satellite cable, got a strange issue with BBC HD channels (them only) would like to see if it works.

That ebay design looks wrong for an F-connector fitting.

You are trying to decrease the signal from the dish ? Why would you want to do that. It will do it across all transponders.

BBC Channels are among the strongest signals out there at the moment since they moved. Ch5 seems to be the strongest on "Astra".

You do not get signal overload on satellite.

snaps

whats the problem your having mike?

mike65

finally back to this, BBC HD and BBC1 HD and only these two channels playing up, stuttery signal as seen below as compared to BBC1 SD

(excuse hand held quality)

https://www.youtube.com/watch?v=ogIv2_ZB6Sk

Someone suggested an attenuator hence my query above. The receiver is a Manhattan Plaza HDR-S, the really curious thing is how the problem is at its worst when the box is first brought out of stand by mode, it gradually improves but never fully settles.

STB

mike65 wrote: »

finally back to this, BBC HD and BBC1 HD and only these two channels playing up, stuttery signal as seen below as compared to BBC1 SD

(excuse hand held quality)

https://www.youtube.com/watch?v=ogIv2_ZB6Sk

Someone suggested an attenuator hence my query above. The receiver is a Manhattan Plaza HDR-S, the really curious thing is how the problem is at its worst when the box is first brought out of stand by mode, it gradually improves but never fully settles.

Its the high symbol rate on DVB-S2 of these channels that is causing the issues with FEC. I have seen it before on Clarke Tech boxes.

This still in warranty ?

If it is not, disconnect it, take the lid, get your missus hairdryer and set it on cold (not hot!) and blow the feck out of the insides. You could use a hoover too. Dust causes this on the CTechs as well.

I am not messing.

mike65

Hmm it is in warranty, the unit has a lot of slats on the casing for ventilation (no mechanical cooling is used on this model) I'll get the vacuum out give it a going over without opening the case.

watty

STB wrote: »

Its the high symbol rate on DVB-S2 of these channels that is causing the issues

More believable than an attenuator!

High SR has caused problems on many boxes over the years that claimed to manage whatever SR.

STB

mike65 wrote: »

Hmm it is in warranty, the unit has a lot of slats on the casing for ventilation (no mechanical cooling is used on this model) I'll get the vacuum out give it a going over without opening the case.

Make sure its disconnected. A strong hoover should do it. The chips in these boxes are super sensitive to dust. When HD channels with high symbol rates on DVB-S2 start acting up, its a sure sign that the chip is working overtime when its starts doing what was in your video (Massive drops).

Might sound mad, but I guarantee it works for you. As i say i had the same issue different box (no doubt same OEM!).

(cooling: they have massive heatsinks on them Mike, but yeah that can be an issue too)

STB

watty wrote: »

More believable than an attenuator!

High SR has caused problems on many boxes over the years that claimed to manage whatever SR.

Watty I took my Ctech 5000c apart to figure out what the issue was. The dust inside all over the board and main processing chip with heat sink was unreal (3-4 years use).

The Signal Q&S bars where hopping and then nothing after that on high symbol rate dvb-s2 tps (the issue doesnt arise with Ch4HD as they use dvb-s with the high S/R). I initially thought it was firmware related.

Hey presto, working again. Some Manhattan boxes where made by Hubtech so I imagine it may be the same issue.

mike65

Bump!

Well the vacuum made no odds.

This aspect

the really curious thing is how the problem is at its worst when the box is first brought out of stand by mode, it gradually improves but never fully settles

was bugging me so I decided to test the heat theory and sure enough it seems I have a box with a weird sensitivity to the cold. I placed a hot water bottle under the unit (not too hot!) and left it for 20 minutes and powered up....BBC HD/BBC1 HD worked fine, I waited to see if it was just coincidence but there were no glitches, I pressed record and left it for a few hours, taking away the bottle after 2 hours and sure enough on play back it was only when the temperature fell below a certain level after the bottle was removed that the hiccups started again.

zg3409

Temperature related faults are normally diagnosed with freezer spray. Heat the unit up, make sure it is working, then freeze various parts until it stops working. This should help isolate the fault. Freezer spray has a very fine straw for this job.

Liameter

mike65 wrote: »

This aspect was bugging me so I decided to test the heat theory and sure enough it seems I have a box with a weird sensitivity to the cold.

Often a symptom of a bad capacitor.
http://www.satcure.co.uk/accs/low_ESR_capacitors.htm

watty

Or a poor joint on a BGA

Liameter

I would tend to agree with Watty. Bad joints may show up with cooling. Let's hope he's wrong because resoldering a Ball Gate Array chip ain't for the faint hearted - although my neighbour has now done it FOUR times inside his Dell laptop! Apparently he puts the PCB in his electric oven. (Don't try this at home, kids.)

mike65

The mainboard is on the link attachment, if you can see the right part/s what should look at/test?

zg3409

From here:
http://www.joinfreesat.co.uk/sneak-peak-at-manhattan-hdr-s/

It seems as if that box has an external power supply. It might be worth trying an EXACT same power supply to see if that helps. Also measure the existing power supply using a digital multimeter meter if possible. (13V 3A)

Also measure the 5.0V and 12.0V to the hard drive (yellow and red wire)

Liameter

zg3409 wrote: »

It might be worth trying an EXACT same power supply

You beat me to it!

However, an external PSU fault wouldn't explain why heating the receiver cures the fault.

zg3409

The power supply may be heating up, without the use of a hot water bottle. However it could be anything. A can of freezer spray should isolate it quickly:
http://www.amazon.co.uk/SERVISOL-200ml-FREEZE-FREEZING-SPRAY/dp/B000ZZSPRK/ref=sr_1_14?ie=UTF8&qid=1354641372&sr=8-14