SDR to outdoor Antenna connection via Direct TV/Dish existing coaxial.

[brawnson]

Hello, I'm looking for a little help with wiring up an outdoor antenna. From browsing the forum it looks like some folks on here are super coaxial savvy. I'm incredibly new when it comes to this type of wiring and quickly get lost in the different types of coax cable.

What I'm looking to do is connect my RTL-SDR V3 to an outdoor antenna. I'm looking at either a Tram 1410 or Taurus D1000 antenna (might ask about this in the antenna forum later)

After having a look about the house, it looks like the easiest method of setting this up would be to use the existing unused DirectTV/Dish cables. There's already an interior wall port (see photo). It runs outside using what looks to be "RG-6 75ohm" coaxial. It then connects to some sort of wiring manifold (see photo) before it heads up to the dish. From the the dish mount I thought I would run a small extension pole/mast and attach my antenna.

So this leaves me with a couple questions.

1. Can I actually use the existing Direct TV/Dish cables?

2. What adapter do I need to connect from the RTL-SDR (which says it has an SMA F connector, currently connected to a 3 meter section of RG173) to the interior wall port?

3. What would I need to adapt from the RG-6 DirectTV/Dish coax cable to the SO-239 connection on the Antenna?

4. And lastly, which cable from the left side of that manifold would I connect to my antenna? In the photo, the cable connecting to the right side of the manifold heads into the house. I don't know if it matters which of the 4 cables on the left I connect to? Assuming they're all joined through the manifold. There's also a grounding wire coming out of the 4 wire bundle that maybe I should connect to the new antenna?

Holy smokes, this turned into a super long post, if you made it this far thanks for the read and I appreciate any help you can provide. Thank you!

 

[popnokick]

Answering each question in order, but pay attention to #4.... important questions / info there. ANSWERS -
1. Yes absolutely IF they are not already connected to the satellite dish or splitter / amp components. As you show in your photo they are standard RG6 75 ohm coax. Your RTL-SDR will work fine with 75 ohm cable to the antenna.
2. You need an SMA male to F female adapter such as

SMA male to Type F female Adapter

SMA male to Type F female Adapter. High quality materials, optimal design, many thousands in stock and available for immediate shipping.

mgs4u.com

...(assuming you are going to use the wall port or a new wall port same as the one pictured). The RG-173 (174?) jumper is rather high loss for the frequencies you want to hear. Consider replacing it with a similar length of RG6.
3. An F female to PL-259 UHF male adapter such as

F-Type Female to UHF Male Adapter

Metal Body | Nickel Plated | Change the Connector

www.showmecables.com

4. From your pic there are four cables coming down from the roof with only one being used. The other three appear to have terminators on them. IMPORTANT: There is no connection between all of those cables being held in place by that block ("wiring manifold"). Each of the cables is a separate and individual connection that shares no common connection with the others. The block is merely a convenience to keep the cables and connectors together. So two different scenarios apply: 1) If your satellite dish is not installed or not actively in use, simply disconnect the cable from the dish (if not already) and use the adapter to connect to the new antenna. The cable likely already runs to the wall outlet inside the house, so then your only remaining task is to jumper to the SDR. 2) If the satellite dish IS in active usage, then you will need to use one of the other three unused / terminated cables running from the roof to the terminal block on the side of the house. Any of the three will work, but you will need to ensure you identify and use the same cable at the roof level and on the side of the house. There are tools available to trace this electrically if it's not readily apparent from visual inspection. Remove the terminator at the block and connect a new section of RG6 cable. That section will be run into the house via the same (enlarged) or new hole as the existing satellite dish cable. You'll then need to change the wall outlet from a single F female on the wall plate to another F female on the plate. Connect the new cable to the back of the wall plate on the new connector, and from there to you RTL-SDR receiver.

 

[prcguy]

In addition to the info above there are two basic versions of the DirecTV Slimline dish. The old original version has a built in 4-port multiswitch that will feed four receivers and will have the four cables going from the LNB to a grounding block as you have. The newer version dish has a built in Single Wire Multi Switch or SWM and only one cable comes out of the LNB then to a common 4-way or 8-way splitter before going to each receiver. I don't see a splitter so you probably have the older version with four identical cable runs to the grounding block.

Either way you can pull off the LNB and disconnect the cable that eventually goes through the wall and use that entire run for your new roof mount scanner antenna. If its too short you can get a double female F adapter off the cable that came out of the LNB and extend the run to wherever your new scanner antenna will live. The RG-6 used for satellite installs is usually very high quality, so unless its 20yrs old and the connections were never waterproofed, it should be fine.

Answering each question in order, but pay attention to #4.... important questions / info there. ANSWERS -
1. Yes absolutely IF they are not already connected to the satellite dish or splitter / amp components. As you show in your photo they are standard RG6 75 ohm coax. Your RTL-SDR will work fine with 75 ohm cable to the antenna.
2. You need an SMA male to F female adapter such as

SMA male to Type F female Adapter

SMA male to Type F female Adapter. High quality materials, optimal design, many thousands in stock and available for immediate shipping.

mgs4u.com

...(assuming you are going to use the wall port or a new wall port same as the one pictured). The RG-173 (174?) jumper is rather high loss for the frequencies you want to hear. Consider replacing it with a similar length of RG6.
3. An F female to PL-259 UHF male adapter such as

F-Type Female to UHF Male Adapter

Metal Body | Nickel Plated | Change the Connector

www.showmecables.com

4. From your pic there are four cables coming down from the roof with only one being used. The other three appear to have terminators on them. IMPORTANT: There is no connection between all of those cables being held in place by that block ("wiring manifold"). Each of the cables is a separate and individual connection that shares no common connection with the others. The block is merely a convenience to keep the cables and connectors together. So two different scenarios apply: 1) If your satellite dish is not installed or not actively in use, simply disconnect the cable from the dish (if not already) and use the adapter to connect to the new antenna. The cable likely already runs to the wall outlet inside the house, so then your only remaining task is to jumper to the SDR. 2) If the satellite dish IS in active usage, then you will need to use one of the other three unused / terminated cables running from the roof to the terminal block on the side of the house. Any of the three will work, but you will need to ensure you identify and use the same cable at the roof level and on the side of the house. There are tools available to trace this electrically if it's not readily apparent from visual inspection. Remove the terminator at the block and connect a new section of RG6 cable. That section will be run into the house via the same (enlarged) or new hole as the existing satellite dish cable. You'll then need to change the wall outlet from a single F female on the wall plate to another F female on the plate. Connect the new cable to the back of the wall plate on the new connector, and from there to you RTL-SDR receiver.

 

[popnokick]

Ahh yes.... forgot to mention: be sure to waterproof the connection from the new antenna to the "new" connector with something such as Nashua self-fusing silicone tape or similar. (Thx prcguy for reminding me to include that.)
And actually one more thing occurred to me as I was looking at the pics again: The satellite dish doesn't really care at what height it is mounted, but for a VHF / UHF scanner antenna "height is king". Any way you can move the entire mount to the peak of the roof? You'll benefit from the additional height & reception range. If the satellite dish is active it will of course need to be re-aimed.

 

[prcguy]

I think to get on the air quickly the OP could remove the dish and start with the scanner antenna on the existing mount, then later get an appropriate mount for the peak of the roof or use a vent pipe, etc. The dish mount is unusual and not really suitable for roof top use. I have a couple of patents on that dish but I must admit I've never seen that mount before.

Ahh yes.... forgot to mention: be sure to waterproof the connection from the new antenna to the "new" connector with something such as Nashua self-fusing silicone tape or similar. (Thx prcguy for reminding me to include that.)
And actually one more thing occurred to me as I was looking at the pics again: The satellite dish doesn't really care at what height it is mounted, but for a VHF / UHF scanner antenna "height is king". Any way you can move the entire mount to the peak of the roof? You'll benefit from the additional height & reception range. If the satellite dish is active it will of course need to be re-aimed.

 

[vagrant]

With those arms on the bracket, the OP could probably mount the antenna to a 5' or 10' aluminum mast and just slip it into the hole of the existing mount. While some of the mast will go into the mount, I'm not sure from the photo if 5' of mast will clear the roofline.

I wonder how long that cable run is though. It may benefit from a low dB gain amp, but that can come later if necessary.

 

[brawnson]

Awesome! Thank you popnokick and prcguy for the thorough and timely response. That helped me out a bunch. I've got the recommended adapters set up in a shopping cart. I need to check a few more things and I should be ready to order.

The DirectTV/Dish is not in use, and as far as I know has been out of commission for a while. I like the idea of connecting to the RTL-SDR directly with RG-6. Assuming I can disconnect those spare coaxial cables from the dish itself, I'll move one cable inside for that. I might end up using another spare to reach up the mast to my antenna. I can see two of the cable ends/connectors from the ground but need to inspect the other two with a ladder, they disappear into the LNB.

Hopefully the original installer did a good job with weather proofing, there's a good chance the setup is 20 years old. I'll have to pull some of the connections apart and see how they look. I imagine you'd see corrosion if water has been getting in?

For now, I'll probably keep the dish mount where it's at and extend from there. I don't think it sits more than 3-5 ft. below the peak of the roof. As far as the cable run, I'm guessing here, but there's roughly 15ft from Dish down to the block. Another 15ft. running horizontally along the house until it goes straight through the wall the the outlet. Then throw in the extra length for the antenna mast, and the indoor section to the RTL-SDR. Could be looking at 50-60ft. total.