Multicoupler

[garys]

I received a nice year end bonus from my boss.

I've been thinking about upgrading the TV splitter that I currently use since it's only marginal as far as I can tell.

I've lived in the same house for 42 years and scanner reception has always been an issue to the northeast. That's because Big Blue sits line of sight between me and Boston and north/northeast. It's better to the south, but still not what I'd like it to be.

I'm currently running a Tram 1410 Scanner 25MHz–1,300MHz VHF/UHF Super Discone Base Antenna, which feeds three scanners and my SDR set up. It works pretty well, although noting is as good as my ST-2 Scantenna did, Sadly it just didn't survive the winter a few years back and it out of production.

For my set up I need five output ports, so it looks like I have two options.

1) Stridsberg MCA108M for about $335.00

2) Cross Country Wireless https://www.crosscountrywireless.net/multicoupler.htm five output port for about $230.00. They are hand built on order and come from England. The few mentions on Radio Reference are pretty good.

Just looking or thoughts on this. I know some people had good luck with Electroline TV splitters, but I can't find any of the eight port versions available.

[Scott]

Hi Gary,

I'm in the midst of yet another reconfig of my radio room, almost done actually, and I decided to try to create a multicoupler myself from info derived primarily at Radio Reference. I am awaiting the actual amplification circuit but in the meantime I substituted a NooElec preamp and actually got some pretty decent results. The forthcoming device will have a much lower noise floor hopefully, and there are other amp options too. It cost me roughly $90 for the parts that will ultimately make an 8 port multicoupler. I started a thread for it at RR:

https://forums.radioreference.com/threa ... er.450915/

As the amp portion of this is relatively cheap, as are the options, I may experiment with a few different types if the one on order doesn't work out.

[garys]

Thanks! I read through that thread. From a quick look, it seems that there might be a guy will will assemble it and he's local. (sometimes)

[MrSvenSven]

Hi Gary,

I'm in the midst of yet another reconfig of my radio room, almost done actually, and I decided to try to create a multicoupler myself from info derived primarily at Radio Reference. I am awaiting the actual amplification circuit but in the meantime I substituted a NooElec preamp and actually got some pretty decent results. The forthcoming device will have a much lower noise floor hopefully, and there are other amp options too. It cost me roughly $90 for the parts that will ultimately make an 8 port multicoupler. I started a thread for it at RR:

https://forums.radioreference.com/threa ... er.450915/

As the amp portion of this is relatively cheap, as are the options, I may experiment with a few different types if the one on order doesn't work out.

I used a very similar setup in a past iteration of my radio room, using a wideband amplifier that was much more expensive. I had found that amplifier by scouring the net looking for the amp with the lowest noise figure I could find. It worked great until the amp died one day. I speculate that it might have been overloaded by someone (probably me) transmitting too close to it and overdriving the input. I'd love to hear how you make out with the cheaper amp because that would probably work great for me, and it won't be as expensive if I blow it up again.

[garys]

Scott, do you have part numbers and sources?

My search hasn't been all that successful so far.

[N9JIG]

I am a huge fan of the Stridsberg line of multicouplers, I have 3 of the 8-port ones and several of the others.

My current setup has an 8-port MCA208M feeding 7 scanners from an ST-2 in the attic and it works great. I found that connecting the antenna directly to the radio works slightly worse than running thru the multicoupler, both with indicated signal strength and perceived voice quality. The pre-amp in the multicoupler seems to help.

If you are using a splitter to serve several radios without a pre-amp you will receive some insertion loss. If you use a pre-amp to counter this and have the ability to place the pre-amp at the antenna rather than at the splitter you will get better performance. Either way do not go overboard on the gain so as to not swamp the radios. The pre-amp in the Stridsbergs are meant to overcome insertion loss but they do end up providing a slightly stronger signal outbound.

[Scott]

Hey Rich, nice to see you here! I have a similar setup now that is doing exactly the same thing with my 8 port Stridsberg, right down to the # of scanners being served by it. My intent here is to replace the Electroline units I've been using. From my post at RR I believe I did the math correctly so I should actually have very little if any gain when the signal is output from the 8 port splitter, but no loss either. In my RF environment I think it may actually be better that I don't have the preamp at the antenna itself. The Stridsbergs operate in the same manner.

Gary, in my RR post there should be links to all of the material that I found to cobble mine together. You will need a 9 to 15 volt DC input for the preamp. Speaking of the preamp it arrived today so I will experiment with it, waiting for a few more short coax jumpers before I make the final build, but what I have now should be useable.

[garys]

I'll go back to the RR thread and check again. I might have just missed it. I've been reading and posting between doing work. Pesky work always seems to get in the way of fun.

ETA: I did look at your list, and then the comments by prcguy. So, now I'm even more confused.

Hey Rich, nice to see you here! I have a similar setup now that is doing exactly the same thing with my 8 port Stridsberg, right down to the # of scanners being served by it. My intent here is to replace the Electroline units I've been using. From my post at RR I believe I did the math correctly so I should actually have very little if any gain when the signal is output from the 8 port splitter, but no loss either. In my RF environment I think it may actually be better that I don't have the preamp at the antenna itself. The Stridsbergs operate in the same manner.

Gary, in my RR post there should be links to all of the material that I found to cobble mine together. You will need a 9 to 15 volt DC input for the preamp. Speaking of the preamp it arrived today so I will experiment with it, waiting for a few more short coax jumpers before I make the final build, but what I have now should be useable.

[Scott]

If I can try to help clear up some confusion don't hesitate to ask.

I just lashed the newly arrived preamp up and it is working very nicely. I need to clean up the install and maybe add a few ferrite chokes (another story around here entirely) but for a temporary setup I'm cautiously optimistic that this is going to do what I want it to do.

[garys]

I have some of the minor components and saved the rest to my Wish List on Amazon. I was more referring to prcguy's comments about CATV amp versus a radio amp. If that makes sense.

Since it's short money, I can buy what I need as soon as you're satisfied it works okay.

If I can try to help clear up some confusion don't hesitate to ask.

I just lashed the newly arrived preamp up and it is working very nicely. I need to clean up the install and maybe add a few ferrite chokes (another story around here entirely) but for a temporary setup I'm cautiously optimistic that this is going to do what I want it to do.

[Scott]

Personally I never had any issues with the Electroline at all but I've always used the "02" models that just overcome the signal loss of splitting a signal 4 or 8 ways. I'll let you know what I think of this setup once I have all of the actual components in place. The Stridsbergs do work great but at a high price. Never tried one of the Cross Country models. I had the rack mounted DLI (I think that was it) 16 port at one point but I always questioned its performance and read that other users had a lot of failures.

As you read in the thread at RR, my mission is to get all of these components in place, and like the multicoupler, leave enough gain to overcome what is in my case a signal being split 8 times, which is about an 11db loss per output with no amplification. Between the amp and the inline attenuator that sits right before the splitter I feel mathwise anyway I have it as close as can be.

[garys]

I'll wait for your review and conclusions. No sense in me duplicating your work since you seem to have a good idea of what's going on. Unlike me.

Personally I never had any issues with the Electroline at all but I've always used the "02" models that just overcome the signal loss of splitting a signal 4 or 8 ways. I'll let you know what I think of this setup once I have all of the actual components in place. The Stridsbergs do work great but at a high price. Never tried one of the Cross Country models. I had the rack mounted DLI (I think that was it) 16 port at one point but I always questioned its performance and read that other users had a lot of failures.

As you read in the thread at RR, my mission is to get all of these components in place, and like the multicoupler, leave enough gain to overcome what is in my case a signal being split 8 times, which is about an 11db loss per output with no amplification. Between the amp and the inline attenuator that sits right before the splitter I feel mathwise anyway I have it as close as can be.

[garys]

As it happens while looking for something else I came across an Antonix CMC2008V splitter. 5Mhz to 1Ghz -11db out.
It seems to be the equivalent of the splitter has in his RR post.

Unless there is an advantage to the other one, I have one component for the project.

[W1KNE]

As it happens while looking for something else I came across an Antonix CMC2008V splitter. 5Mhz to 1Ghz -11db out.
It seems to be the equivalent of the splitter has in his RR post.

Unless there is an advantage to the other one, I have one component for the project.

-11db is quite a bit of loss, FYI. Also the loss factor should vary based on frequency. (Usually more the higher you go).

[garys]

I'm following Scott's lead on this and just wondering if there is a difference between brands.

-11db is quite a bit of loss, FYI. Also the loss factor should vary based on frequency. (Usually more the higher you go).

[Scott]

Generally, splitters run like this:

2 way: 3.5db loss per port
3 way: 3.5db to 2 ports, 7db to the third
4 way: 7db loss per port

So the math on the 8 way may or may not add up but I planned to try to as best possible balance the output so my setup acted at least similarly to that of the Stridsberg by overcoming the loss per port for the 8 way splitter. I came within a db of doing so and figured on some negligible additional loss from the involved cabling.

As has been mentioned though different frequencies are going to result in different levels of loss, not only with the splitter, but also with the preamp being used.

Mine is set up in its final configuration, and I will eventually provide some photos of how I have it set up when I release my "new for '23" shack photos. I will say that for me it seems to equal or exceed the performance of the Stridsberg 8 port but a lot more testing and comparison is warranted and with Christmas and all of its related activities I haven't had time to do so.

[garys]

Thanks. The physical layout of the splitter I plan to use is a bit different than what you have, but that's a matter of changing one jumper from what you are using. I'm going to go ahead and order the rest from Amazon and see how it goes.

Even though I'm 144 feet above sea level, reception is iffy all over my house. I'm about a mile from the Brockton line, but sometimes have difficulty hearing Brockton PD on a portable without an outside antenna. The outside antenna improves reception overall, but it's always been iffy to the North and Northeast.

The struggle is real!

Generally, splitters run like this:

2 way: 3.5db loss per port
3 way: 3.5db to 2 ports, 7db to the third
4 way: 7db loss per port

So the math on the 8 way may or may not add up but I planned to try to as best possible balance the output so my setup acted at least similarly to that of the Stridsberg by overcoming the loss per port for the 8 way splitter. I came within a db of doing so and figured on some negligible additional loss from the involved cabling.

As has been mentioned though different frequencies are going to result in different levels of loss, not only with the splitter, but also with the preamp being used.

Mine is set up in its final configuration, and I will eventually provide some photos of how I have it set up when I release my "new for '23" shack photos. I will say that for me it seems to equal or exceed the performance of the Stridsberg 8 port but a lot more testing and comparison is warranted and with Christmas and all of its related activities I haven't had time to do so.

[garys]

I finally getting back to this after what seems like forever.

I followed Scott's plan as outlined at Radio Reference, I bought the components and put it all together. I used a 12v wall wart I had around to power the preamp, but all else was as Scott described it except that I used some jumper cables instead of just connectors to assemble the components. That was just for ease of assembly and I might still make some adjustments.

Overall, I'm very happy with the results. Aircraft AM is much improved into my 536HP, although that's not a major consideration. UHF is also better, especially Boston PD. Some of the district channals (Area A and Area D) can be hard to pick up at my QTH, but after listening for a while they both have good audio. 700/800 are also improved a bit.

The only area that seems pretty much the same is 800 into my Airspy. That said, it's only on the 851.3625 for Quincy DPW, but that signal is pretty bad and the rest of the 800 band seems fine. 900Mhz into Airspy is fine, maybe a bit better.

Overall it seems like a win.