Bi-Directional Multiswitch?

[Xing]

I know the bi-directional multiswitch exists. The problem is the only one I have found is $400 made by Terk, Terk T2 MS-58. I need the bi-directional because my customer has Comcast HD and Directv HD. He currently has a 5X8 multiswitch D* provided and the cable is into the OTA input and is diplexed after it comes into the house. He still only has the mpeg2 programming for D*. The Comcast VOD won't work because it can't aquire an IP address through the multiswitch. Both Comcast and D* have come out and checked on everything and they had not heard of a bi-directional multiswitch. I need to know first if this will work with a bi-directional multiswitch and second if D* or Comcast offers anything that is comparable?
If not is there any suggestions on how to run this system and everything to work without running a second line into the house.

Thank You

[veryoldschool]

Move the cable from the multi-switch [input] to a diplexer on the output.
So [multi-switch] diplexer -> cable -> diplexer -> both outputs.
Make sense?

[Xing]

Not sure, you saying to put the cable line directly into the first diplexer, bypassing the multiswitch, then use another diplexer into the house?

[AntAltMike]

Hmm. Another Terk ripoff. I guess a bi-directional 5x8 switch is one in which the switch's internal diplexer has a low end CATV path rolloff frequency low enough for the sub-band return signals to take that path rather than to be routed to the DC/22KHz path.

The marginal cost of manufacturing a multiswitch with a lower rolloff point like that is roughly zero. I wouldn't be surprised if some other multiswitches have suitable rolloff points, but unfortunately, technical specs for multiswitches ar few and inadequate.

If you use diplexers as veryoldschool is recommending, just make sure that they are rated low enough to support the return signal. In my market, I think it is at about 10.5 MHz. Holland diplexers that says their "Ant" or cable port passes down to 5MHz sell for a couple of bucks each.

[AntAltMike]

I see that the Sonora and Holland HMS-58C multiswitch says it passes signals down to 15MHz, and I have successfully used a Sonora destacker with a cable TV passband similarly rated down to 15MHz in Comcast systems with return signals. The 15MHz pass spec is not a hard crossover point. That may be the guaranteed, "3dB" rolloff point, meaning that you may have slighly higer return signal path loss below that, but I'm sure it will be insignificant. You can buy this switch on the internet for about $125.00, but again, make sure that your diplexer at the receiver/cable box end is rated down to 5 or 10MHz. Many diplexers start rolling off at about 40MHz.

[carl6]

Xing,

If at all possible, just run another RG6. Usually cheaper and more reliable than any kind of diplexing.

Carl

[AntAltMike]

I do have some reservations about an installer using the HMS-58C in this application without getting further info on that product. If the cable.antenna splitting is passive, then there would be about 14dB of loss in each direction. Even if your TV signal can withstand that loss, a cable modem's return signal might not. I don't believe that the return path signals of cable boxes are as finicky however.

If you are a dealer, you can call Sonora Design directly and get the definitive word on cable signal losses in both directions. If you call a distributor or dealer, you will not know for sure if their answers are reliable.

[Xing]

I can't run another RG6 becase the customer doesn't want another hole drilled for the cable.

All the information given has been very helpful and thank you. I think we decided to run a series of diplexers.

[veryoldschool]

I can't run another RG6 becase the customer doesn't want another hole drilled for the cable.

All the information given has been very helpful and thank you. I think we decided to run a series of diplexers.
"Just know" that the BBC needs to be indoors, so the first diplexer and BBC need to be out of the weather.