Question about loop out

[qwert1515]

Yes, Also the Coolsat should be on the same polarity that you need the USB tuner to tune.

 

[gmd63]

I have 3 linked together by the loop out.
Pansat 9200HD (with DVB-S2 card) as the main receiver. AZBOX to the Pansat for 4:2:2 finds, and my big old C-Band analog receiver looped out from the AZBOX.

 

[tonydix]

Prebumably it is important to switch off the power to all the LNB,s except to the master one connected to the LNB on the dish ?
Any other setting need changing ?
Thanks
Tony

 

[John Popper]

Yes, Also the Coolsat should be on the same polarity that you need the USB tuner to tune.

oh! I had not thought about that. On C Band it's not gonna be a problem since I already control polarity via my analog receiver, but on Ku Band I guess I'm gonna have to scan first V and then H whenever I use the DVBWorld.
Thanks for the heads up qwert

ps. it's either that, or use a high freq splitter dividing the Ku cable into 2 and not turning on the coolsat whenever I use the DVBWorld for Ku. But then I would have to connect and disconnect the cables I'm using via the disecq switch. Thinking about it, im better off just using the loop out

 

[qwert1515]

Another note, with some receiver (The Pansat 3500 allows this) when you turn them off,
a slaved receiver (a receiver connected to the loop out port) is allowed to control the polarity,
but I checked with the Coolsat 6000 and it did not.

 

[John Popper]

thanks for the info qwert

 

[Zorak]

Is there any resource that shows how each product's loop out port behaves? I've used a DC block to be safe between my main and slaved receivers but was unaware that a looped receiver could control polarity when placed behind some receivers as mentioned in the post above. My use of loop out has been pretty limited though. I typically use a Coolsat 4000 or 5000 for blind scanning and then do a simple connect with a DC block between the Coolsat's LNB out and the slaved receiver's LNB input to be able to receive either analog, HD or 4:2:2 signals with the slaved receiver. I've always assumed I'd need the master receiver set to the desired polarity and to be powered up. I was worried about passing voltage through the master receiver form the slave. Is there a better way to do this? Thanks!

 

[brentb636]

I don't believe that there is such a resource. My Mercury II behaves impeccably with the loop out in use. Apparently Fortec incorporated a DC block in the ciruitry, or isolated it somehow. When the Merc II is in standby, my AZbox, attached to the IF output of the Merc II, has full control of the lnbf ( and motor , too, if the motor were on the Merc II ) . Other recievers , like my CS8000 cannot stand having something attached to their loop out port without anomalous behavior .

 

[B.J.]

Is there any resource that shows how each product's loop out port behaves? I've used a DC block to be safe between my main and slaved receivers but was unaware that a looped receiver could control polarity when placed behind some receivers as mentioned in the post above. My use of loop out has been pretty limited though. I typically use a Coolsat 4000 or 5000 for blind scanning and then do a simple connect with a DC block between the Coolsat's LNB out and the slaved receiver's LNB input to be able to receive either analog, HD or 4:2:2 signals with the slaved receiver. I've always assumed I'd need the master receiver set to the desired polarity and to be powered up. I was worried about passing voltage through the master receiver form the slave. Is there a better way to do this? Thanks!

It's strange... for most electronic devices sold in the US, there is an FCC ID# printed on the back, and you can go to the FCC site, and look up the FCC ID# for the device, and sometimes there will be a schematic or block diagram, sometimes it will be confidential, but you can usually find out some info about the product. However, with almost every sat receiver I own, there is no FCC ID# printed on them, even receivers that were made in the US. I understand that with the speed at which this technology is moving forward, that receivers would be obsolete before they were type accepted by the FCC, so maybe they have gotten less strict about inforcement, or perhaps companies are just ignoring the need for registering with the FCC?

 

[John Popper]

Is there any resource that shows how each product's loop out port behaves? I've used a DC block to be safe between my main and slaved receivers but was unaware that a looped receiver could control polarity when placed behind some receivers as mentioned in the post above. My use of loop out has been pretty limited though. I typically use a Coolsat 4000 or 5000 for blind scanning and then do a simple connect with a DC block between the Coolsat's LNB out and the slaved receiver's LNB input to be able to receive either analog, HD or 4:2:2 signals with the slaved receiver. I've always assumed I'd need the master receiver set to the desired polarity and to be powered up. I was worried about passing voltage through the master receiver form the slave. Is there a better way to do this? Thanks!

Now Im a bit confused, Im trying to do exactly what you are doing (except im gonna use a DVBWorld USB tuner) but I thought I didn't need to use a DC Block coming out from the Coolsat Loopout, wouldn't the loopout already block the voltage?

 

[brentb636]

Now Im a bit confused, Im trying to do exactly what you are doing (except im gonna use a DVBWorld USB tuner) but I thought I didn't need to use a DC Block coming out from the Coolsat Loopout, wouldn't the loopout already block the voltage?

Some receivers do block the DC, some don't seem to. The only CERTAIN thing is to use your own external DC block. The sad thing is that not all receivers models perform equally.

 

[qwert1515]

I have used the DVBWorld USB tuner, Twinhan 102G, Broadlogic 2030, Pansat 2700/3500 slaved to the Coolsat 6000 without a DC block,.

The only time I have used a DC Block (Homemade splitter with a capacitor connected to one port) was when I connected an analog satellite receiver, I did not want to take a chance.

 

[John Popper]

I have used the DVBWorld USB tuner, Twinhan 102G, Broadlogic 2030, Pansat 2700/3500 slaved to the Coolsat 6000 without a DC block,.

The only time I have used a DC Block (Homemade splitter with a capacitor connected to one port) was when I connected an analog satellite receiver, I did not want to take a chance.

Good to hear that!

I also use a DC Block on my analog receiver

 

[Mr Tony]

yeah it seems like analog receivers are the only reason to use a dc block on a loop out

 

[Zorak]

The original thread I saw on slaving a receiver was about an analog receiver and it suggested using a DC Block. I thought the same logic applied to all receivers so I've continued to use one to be safe. I have noticed some quirks when I've used the Coolsat as a master but am glad to know about the Fortec. Good luck!

 

[B.J.]

The original thread I saw on slaving a receiver was about an analog receiver and it suggested using a DC Block. I thought the same logic applied to all receivers so I've continued to use one to be safe. I have noticed some quirks when I've used the Coolsat as a master but am glad to know about the Fortec. Good luck!

In my opinion, there is no difference between analog/digital relative to the logic with respect to using a DC block. I absolutely NEVER connect the inputs of any two receivers without using a DC block. In fact in one case I needed to use TWO DC blocks to get things to work right (must admit that I don't understand that one).
The simple reason for using a DC block is that when you have 2 receivers, both of which are putting out DC voltage to power an LNB, it simply isn't worth the risk of the two DC power supplies fighting each other, and possibly doing damage to one of the receivers.
In SOME cases, FTA receivers with passthru's MAY incorporate DC blocks in their design to protect their circuitry, and MAY stop their voltage from getting through to receivers connected further down the line, but as has been mentioned above, unless you have the schematic for the receiver, there is no easy way to tell what is going on in the passthru.
I have seen posts from people who have used the passthru without a DC block. These people were careful to not have both receivers on at the same time, and they were able to control the LNBF polarity by the DC passing through the passthru, only when the master receiver was switched off.
Without schematics, there is no way to tell for sure, but my impression is that some passthrus are simply that, simply something like a splitter that the master taps off, perhaps with a DC block to avoid interaction of the DC voltages, perhaps not. However other passthrus are definately amplified. Ie the signal comes into the master, and then after the master extracts IT'S signal, it runs the signal through an amplifier so that the slave receivers often get a higher signal level (and higher noise) that the original signal. If you don't use a DC block on an arangement like this, you are feeding DC voltage into the back end of an amplifier stage. I just can't imagine anything good coming out of that.

Anyway, I use passthrus all the time. At times I have had 5 or 6 different receivers fed off the same signal using 1 splitter and 3 passthrus. However I ALWAYS use DC-blocks between every connected receiver. It's just not worth the risk of damaging something. I also tend to not trust those one leg power passing splitters, because I have found that some of them are not completely DC-blocked, particularly if you happen to hook up the receivers to the wrong ports accidently, which I did once, which ended up sending DC voltage back into one of my computer card receivers, which ended up putting my computer into one of those blue screen of death things (it eventually recovered).

Some people connect receivers without DC blocks, and don't have any problems, but I think this is really receiver specific, and eventually they will try this with a receiver that has a passthru with a different design, and it will end up causing damage.

Just my opinion.

 

[Tron]

Interesting discussion regarding the use of DC blocks. With my two Visionsats, I'm not using blocks. If my master is on and I turn on the slave receiver, the master will show a momentary glitch on the screen. Its nothing big, just minor pixelation on part of the screen that lasts for maybe two or three frames. For that reason, I never power the slave on while I'm recording something on the master. The point is that powering the slaved receiver is affecting the master, even if only briefly.

 

[SATisfied]

Wow, this turned in to a long thread with lots of interesting info.....thanks for everyone's input. I am getting an FTA education. When do I get my diploma? lol

 

[sideswiper]

you learn something new every day in this great hobby

 

[Ironsides]

ummm

Wow I am confused as pie...I have a Nuesat and a Uniden Supra Hooked to a splitter so I can use the C-Band LNB on both boxes. I also have an A/B for Ku/C-band on the Neusat. No DC Blocks at all. I can turn off LNB power on the Neusat settings so I don't need power from the Neusat to the C-Band LNB I just let the Uniden do that for me. On the Loop out from the Neusat I have a Dreambox 7020 hooked up and I use it to record because it has a built in Hard Drive. I always have the Neusat off IF I am using the DB. The power stays on all the time on the Uniden Supra. But I have never actually used a DC Block of any kind. Maybe I am just lucky...I never saw a real need to use a DC block but maybe I should consider it before something smokes besides my pipe! By the way I have had this same hookup for several years and never had any issues that I know of...