How to diplex ANT with HR20 and SWM8

[flipptyfloppity]

I thought I understood diplexing, but it appears perhaps I don't.

I have my antenna hooked to the power inserter to the SWM8 (port 1). I then go to a splitter (2GHz) and one of each of the outputs goes to the single SWM input of the HR20 (no baseband converters).

So that all works great. Both HR20s get DTV. In addition, I've had one hooked to an antenna directly (not diplexed), and I get a lot of channels.

But I want OTA at both HR20s, so I want to diplex (it's most of the reason for the SWM, honestly). So I figured all I have to do is get two diplexers, hook the ANT into the "TV" input on one, and the SAT into the other input. Then the single wire out goes to another diplexer, and I take the SAT output of that and hook it to the SWM input and take the "TV" output and hook that to the ANT input of the HR20.

Well, it works if I hook up everything BUT the wire from the 2nd (near) diplexer TV signal to the "ANT" on the HR20. If I hook up the "TV" output from the near diplexer to the HR20's ANT or even 2nd SAT input the SAT signal goes away.

I'm not even getting into whether the antenna signal is working, in fact, even if I don't hook up anything to the "TV" input on the upstream end or even if I don't even have the upstream diplexer installed AT ALL, hooking up this one cable knocks out the SAT signal.

I tried putting the far (inserting) diplexer both above and below the splitter. I tried removing it completely.

What am I doing wrong?

(I'm asking his here, even though I'm mentioning SWM, since apparently SWM isn't undercover anymore, just not sold to single family dwelling customers.

[houskamp]

Do you have a FM trap handy? a close FM station here wipes out everything..

[flipptyfloppity]

Do you have a FM trap handy? a close FM station here wipes out everything..

Hmm? Another trap to install here by the receiver? No. My antenna amp does have an FM trap, and I have it in (i.e. removing FM), although again in these cases I don't even have my antenna hooked up (or any upper diplexer at all) and it still fails to work.

Thanks for looking at my problem. I'll try to install a local FM trap if no one else comes up with a more likely idea.

Also, I didn't mention I tried several diplexers, and they're DTV approved diplexers. Oh, and I tried it in the other room on my other HR20 too. Oh, and when I hook this up and it knocks out reception on one of my HR20s, the other is unaffected even though in theory with the splitter in there, it's all one cable segment.

[houskamp]

also isn't there an "ant in" on the swm8?

[Kansas Zephyr]

The coax goes directly from the OTA antenna into the "Off Air" input on the SWM-8.

It should not go through the power inserter.

Then:
FTM/SWM 1/Power Output---coax---power inserter--coax--(splitter if necessary for multiple receivers)--coax--diplexer--sat output to sat 1 input (and antenna output to OTA input)

FTM/SWM 2 Output--coax--(splitter if necessary)--coax--diplexer--sat output to sat 1 input (and antenna output to OTA input)

[flipptyfloppity]

I'm told that you can diplex separately instead of using the ANT IN on the SWM8. Diplexing separately is more convenient for me since the SWM8 is outside and my antenna in in the attic.

Considering that even operating with no upstream diplexer at all still causes this problem, do you think it really matters if I diplex upstream with the SWM or with a separate diplexer?

I could forward my antenna outside using one of the other 3 dish coaxes I am no longer using. But I don't really think it'll make any difference since the thing that causes the problem is connecting the wire from the near (separating) diplexer to the HR20 is what causes the signal to go, nothing involving the upstream (inserting) diplexer.

However, I will put this on my list of things to try when it is light out tomorrow.

[houskamp]

All we can do is try stuff.. we have some experience with the SWMs, but still learning new things.. guess we're all working on writing the manual for them :)
let us know what you find..

[Kansas Zephyr]

I'm not sure I understand the "flow" of your OTA antenna through the system.

Please break it down, So we can make sure we know exactly how you are wired.

For example:

OTA antenna--coax--??--coax--??--diplexer--OTA input.


If you are dixplexing downstream of the SWM-8.

Then:
SWM1/Power--coax--power injector--diplexer--coax--(splitters as needed)--coax--diplexer--coax--SWM sat input
Antenna--coax----------------------diplexer.......................................... .......diplexer--coax--OTA input

[flipptyfloppity]

Here's a flow chart:

ANT->ANT booster (CM7777)->80' RG6Q run ->ANT booster power inserter->upstream diplexer TV input
Slimline x4 3' RG6Q runs -> SWM8
SWM8 SWM1 out -> 15' RG6Q run -> SWM power inserter -> upstream diplexer SAT input
SWM8 SWM2 out is terminated
SWM8 ANT input is not connected at all.

upstream diplexer in/out->2-way 2GHz splitter

From the 2GHz splitter, there are two roughly 60' RG6Q runs, one to each of two rooms. Each room has a connector on the wall to an about 5' RG6 run to a downstream diplexer in/out. From the diplexer TV out, I hook a short cable run to the HR20 ANT input and from the diplexer SAT out I hook a short cable run to the HR20 SWM input.

From your diagram, it would go like this (== is the merged segment):
OTA--5' coax--OTA inline amp--80' coax--OTA amp power inserter--diplexer== splitter==60' coax== diplexer--ANT input
SWM1--15' coax--SWM8 power inserter--short coax--diplexer==splitter== 60' coax== diplexer--SAT input

One thing I tried this morning is getting rid of the VERY SHORT segments after the diplexer behind my HR20. I had made some nice 5" segments of RG6 to hook the diplexer up. Well, part of me knows short segments are very bad and can lead to ringing. So I replaced the short segment between one HR20's ANT input and its diplexer and lo and behold, it seemed to not lose signal when I attached it!

I didn't have the upstream diplexing in at the time, so I couldn't test to see if the antenna was working, but I'll try that tonight. Perhaps my problem all along (including when I failed to diplex in 2004, before Ka/Ku) is that I liked those short segments and they're bad.

[flipptyfloppity]

Well, now even more interestingly, I found that it works if I have (about) 12' of cable between the ANT input on the HR20 and the (downstream) diplexer. 5" is no good. 3' is no good. 7' is no good. But if I hook a 3' segment from the ANT input to a barrel to a 4' segment to a barrel to a 5' segment to the TV output on the diplexer, it works.

On the theory that the HR20 just didn't like its inputs having less than 15' between them, I moved a 4' segment from the ANT side to the SAT side, so now the HR20 had 7' from the SAT input to the SAT output on the diplexer and 8' from the ANT input to the TV output on the diplexer. That didn't work either.

I haven't actually tried to see if the ANT signal is surviving the diplexing, I'll hook the upstream diplexing back up tonight as soon as my primetime recordings are done.

[odorcide]

Do you think the antenna signal is to hot? I've had problems in a MFH-1 system while diplexing a OTA feed on the line and killing the S/N ration for the sat signal. Threw a attenuator on the diplexer and it was good to go.

[flipptyfloppity]

Do you think the antenna signal is to hot? I've had problems in a MFH-1 system while diplexing a OTA feed on the line and killing the S/N ration for the sat signal. Threw a attenuator on the diplexer and it was good to go.

That would seem obvious, except... I did all this testing without even having the upstream diplexer installed. That is, there was no ANT signal on the line at all!

I hooked up my bedroom HR20 with a 15' cable (not the 3 connected short ones) between the diplexer and ANT and it received SAT just fine. So I put the upstream diplexer in and gave it a check and the bedroom receiver was receiving both ANT and SAT just fine. So took the 3 segments totalling 12' and put it in with a diplexer in my living room and now that works too. So I have diplexed ANT and SAT working in both places.

I'll go out tomorrow and get some more white RG6 to make 15' jumpers from and some ends (I'm out now after making 3 cables today) and then I guess I'll coil up the 15' wires with some wire ties and screw everything down in the wiring closet and call it done.

But does anyone understand why I need to put a 15' jumper on the TV output of the diplexer before attaching it to the HR20?

[Capt'n]

Sounds like your having cable issues. Maybe your not getting the cable ends installed properly? I doubt the cable lengths have anything to do with it. Your talking a couple feet between two cables that are not that long to begin with. Now that you have it working. Try putting in a shorter cable in place of the 15' cable and see what happens. Maybe you needed some trial and error before and now you have it hooked up right.

[eakes]

This sounds like a return loss problem - that is - the desired satellite signal is splitting at the diplexer, goes to the TV input and does not see a proper termination, reflects back down the coax, into the diplexer and arrives at the satellite input out of phase with the desired signal. The result is the reflected signal cancels a portion or all of the desired signal. The receiver thus sees "no signal" or one that is weak and breaks up. In digital transmission parlance this is know as multipath. In the microwave transmission world the digital microwave receivers are designed to compensate for some degree of multipath but receivers such as those used by Directv and DISH are not designed with these protections.
The additional coax introduces loss which would reduce the level of the undesired signal and the length will change the phase of the reflected signal such that it is not canceling as much of the desired signal.

One thing to try instead of the length of coax is to put a regular TV splitter in the line between the TV output of the diplexer and the TV receiver input. This should introduce enough loss to minimize the reflected signal.

[jwd45244]

To Diplex OTA with an SWM8 not using the OTA port on the SWM, Connect it this way:

Dish -----> SWM8-----> Power Inserter (PI) at least 15' of RG6 between SWM8 and PI

PI ----> SAT In on combining diplexer
OTA Antenna -----> VHF/ UHF In On diplexer

Diplexer ---Splitter--> Splitting diplexer (at each receiver) ----> SAT In
Splitting diplexer ----------> OTA In

Not all diplexers are created equal. I user Channel master (CM4002IFD) for the combining diplexer and CM4001IFD for the splitting dipelxers. You can find them very inexpensive on www.solidsignal.com

[flipptyfloppity]

Sounds like your having cable issues. Maybe your not getting the cable ends installed properly? I doubt the cable lengths have anything to do with it. Your talking a couple feet between two cables that are not that long to begin with. Now that you have it working. Try putting in a shorter cable in place of the 15' cable and see what happens. Maybe you needed some trial and error before and now you have it hooked up right.

Changing nothing but the cable between the diplexer and the ANT input on the HR-20 changes the result. The longer lengths don't show the problem, shorter lengths do. This is the case even the longer length is actually made up of three of the shorter lengths connected together with barrel connectors!

eakes:
Another oddity is this problems shows if I hook the TV out of the diplexer to the 2nd SAT input (unused on my SWM setup) of my HR-20. It would be odd to me if the sat signal didn't find proper termination at the SAT input!

I also don't think the sat signal should be going down the antenna leg!

But I don't disagree something like this is happening. I just can't figure out how.

I'd love to have fancier diplexers, but I have what I have. I'm actually closer to giving up on diplexing and using the spare 75 ohm wire (now unused due to SWM) as the antenna signal carrier anyway. It'll mean other rooms (that only have one coax) can never have OTA, but since I don't use those rooms at the moment and DTV will likely have my local PBS affiliate soon anyway, maybe I don't care.