RF Distribution Problem

Willby

My son wanted to distribute the output from a satellite stb and a Sky HD box to a distribution amp supplying signals to two bedrooms.
The sat stb (Skyboxf3) has no rf op so I took a composite op and put it through a modulator. I then routed the op from the modulator to the RF in on the SKY HD box.
The RF2 op from the SKY HD box is fed to the distribution amp. The result is perfect pictures on an old Toshiba CRT tv in one bedroom. However on the tv in the second bedroom (Samsung LCD ) the results are less satisfactory. The picture from the SKY HD box is perfect but the picture from the sat stb is black and white.
The colour setting on the Samsung tv is set to auto. I changed it to Pal but the picture was unstable and still b&w.
I also tried a different lead from the stb to the modulator . At present it has phone connectors both ends. The first I tried was phono/scart. The skyboxf3 only has phono output or component.
I also tried various different frequencies from the modulator.
Any advise as to what else I could try would be appreciated.

pegasuspub

Hi can you swap the bedroom tv's and see how the picture is ,this should narrow it down,is there a gain control adjustment on the rf modulator?
did you try the modulator on a low channel number eg 21 as this may increase its range?

Willby

pegasuspub wrote: »

Hi can you swap the bedroom tv's and see how the picture is ,this should narrow it down,is there a gain control adjustment on the rf modulator?
did you try the modulator on a low channel number eg 21 as this may increase its range?

No gain control on modulator. Only tried channels higher than 35 but will try 21 tonight when I will be in my sons house . Thanks for suggestions and will post update.

Willby

The problem appears to the analogue tuner in the Samsung flat screen lcd tv.I took this tv from the bedroom and connected it directly to the output of the modulator . It still only displayed a strong b&w picture.
When I connect the composite signal to the tv directly it displays colour picture ok.
I would suspect the modulator except for the fact that it works ok on old crt tv.

Peter Rhea

Did the Samsung just find the modulator channel on an autotune or did you try manual tuning?

Willby

Peter Rhea wrote: »

Did the Samsung just find the modulator channel on an autotune or did you try manual tuning?

I tried both Peter and also changed the colour setting from auto to Pal etc but nothing seems to work.

winston_1

Is the modulator defiantly PAL I i.e. 6MHz sound? Is it adjustable? If it is set to say 4.5MHz it would kill the colour.

Willby

winston_1 wrote: »

Is the modulator defiantly PAL I i.e. 6MHz sound? Is it adjustable? If it is set to say 4.5MHz it would kill the colour.

It is a standard Mercury modulator and there is nothing adjustable bar the output frequency. I have also had this modulator working in my own home doing a similar distribution job without any problems. I only changed it to install a trilink .
When I get my hands on another modulator I will change the Mercury and see what happens. Meanwhile thanks for all your contributions.

Antenna

Maybe the FTA satbox is accidentally set to output 525line/NTSC ? (the simple 25fps->30fps conversion done by the box leads to a noticeable judder with moving scenes BTW)
non-Freesat/Saorsat FTA boxes usually can be set to ouput NTSC

One TV can fully display such a signal via a modulator, whilst the other TV will display it only in black and white?

A JVC CRT TV at home can display 525line/NTSC colour via the non-RF inputs (i.e. composite socket, composite via SCART). It will also do so via a modulator but only if the modulator is tuned-in on the TV's channel 0 (intended for VCR modulators) . It will only display a Black and White picture of it if it is saved on any other channel position!

winston_1 wrote: »

Is the modulator defiantly PAL I i.e. 6MHz sound? Is it adjustable? If it is set to say 4.5MHz it would kill the colour.

And of course result in no sound too.

Willby

Antenna wrote: »

Maybe the FTA satbox is accidentally set to output 525line/NTSC ? (the simple 25fps->30fps conversion done by the box leads to a noticeable judder with moving scenes BTW)
non-Freesat/Saorsat FTA boxes usually can be set to ouput NTSC

One TV can fully display such a signal via a modulator, whilst the other TV will display it only in black and white?

A JVC CRT TV at home can display 525line/NTSC colour via the non-RF inputs (i.e. composite socket, composite via SCART). It will also do so via a modulator but only if the modulator is tuned-in on the TV's channel 0 (intended for VCR modulators) . It will only display a Black and White picture of it if it is saved on any other channel position!

Hi, just read your post and will check out when I visit my Son's house and will update outcome.

Willby

Antenna wrote: »

Maybe the FTA satbox is accidentally set to output 525line/NTSC ? (the simple 25fps->30fps conversion done by the box leads to a noticeable judder with moving scenes BTW)
non-Freesat/Saorsat FTA boxes usually can be set to ouput NTSC

One TV can fully display such a signal via a modulator, whilst the other TV will display it only in black and white?

A JVC CRT TV at home can display 525line/NTSC colour via the non-RF inputs (i.e. composite socket, composite via SCART). It will also do so via a modulator but only if the modulator is tuned-in on the TV's channel 0 (intended for VCR modulators) . It will only display a Black and White picture of it if it is saved on any other channel position!



And of course result in no sound too.

Hi Antenna,
Glad to report that thanks to your post I have been able to resolve the problem. I checked the video output setting of the box and it was set to 1080_60. Resetting this to 1080_50 solved the b&w picture on the Samsung LCD tv. Simple in the end and when I think of all the time I spent trying to solve it!
Thanks to all who contributed.

Antenna

Willby wrote: »

Hi Antenna,
I checked the video output setting of the box and it was set to 1080_60. Resetting this to 1080_50 solved the b&w picture on the Samsung LCD tv. Simple in the end and when I think of all the time I spent trying to solve it!
Thanks to all who contributed.

1080_60 / 1080_50 are of course what the HDMI output is. However your SCART/composite output changes to either the American 525-line NTSC (also a 60Hz field system) or the 625-line PAL used here and most of Europe (a 50Hz field system) to correspond to the selection of _50 (for Europe etc) or _60 (USA etc).