High Capacity Multicoupler Alternatives

[N9JIG]

Here is what I have now:

I have 4 ST-2 antennas in the attic (I live in an HOA, no outside antennas allowed). One works great and the other 3 not so much. The one that works well is off by itself and the three that do not perform well are close to each other and the HVAC system.

Each is connected to a Stridsberg multicoupler and feeds scanners. There are 3 8-port and a 4-port and 24 scanners are connected to the group, 20 in the cabinet and 4 on the desk.

I am going to try to place the other antennas at better locations in the attic but it is already crowded and I may not be able to spread them out enough to make a difference.

I am thinking about trying to share this well-working antenna with more radios that the current 8-port Stridsberg allows.

I am considering a couple scenarios:

1. The DLI 16-port multicoupler (Wideband RF Multicoupler - 16 Radios, Surge Protected, 50 Ohm) assuming it is still available. This would replace two of the 8-port Stridsbergs int he cabinet. Assuming I can get one of the other antennas to a good location it might be enough.
2. Using the existing multicouplers in a daisy-chain (Running the 3 8-ports connected to the 4-port which is connected to the antenna)
3. Using a decent TV amp ahead of a passive splitter to feed the multicouplers. (The amp is a Wingard that I have had for years and has always performed well.)
4. Using the same decent TV amp ahead of a passive splitter which in turn feeds other passive splitters.
5. Getting some high-capacity TV distribution amp system with 20 or more ports.

I have no problem with TV gear and can make cables with BNC on one end for the radios and F on the others.
Has anyone done anything similar to this and can share their experiences?

 

[prcguy]

In your case I would make my own multicoupler. I would not use a CATV amp but instead a very high level, reasonable noise figure amp from MiniCircuits should be just fine and also one of their 16-way dividers. I have used dozens of different preamps here and only one or two have ever survived here in RF hell. I have had very good success with the MiniCircuits ZHL-1010 amplifier which is only about 9 or 10dB gain and you would need a good 15dB to make up for losses in a 16-way divider.

The MiniCircuits ZHL-2010 is basically a dual stage version of the amp that works well here with about 20dB overall gain. That would leave you with maybe 5dB more signal than you started with or you could use a 3 to 5dB attenuator after the amp. Anyway, here are the components I would consider for a 16-way VHF/UHF multicoupler that will put anything that Stridesberg makes to shame.

I came up with these components within a few minutes and a longer search might find something better. But I would not compromise on the IP1 and IP3 ratings of the amplifier, or you might be disappointed.

20dB gain amp 50 to 1,000MHz:

https://www.minicircuits.com/pdfs/ZHL-2010+.pdf

16-way divider 10-2,200MHz:

https://www.minicircuits.com/pdfs/ZC16PD-222-S+.pdf

 

[Ubbe]

The mini-circuit amp have an extremely good high signal overload performance that probably are not neccesary for indoor antennas. It also has a bad noise figure of almost 4dB. Their splitter are focused at having low phase shift and perfectly balanced attenuation for all ports, only really neccesary when doing measurements and equal lab works.

I would suggest a low noise amp, less than 1dB, with good IP3 of 40dBm and then a 1-4 splitter to feed your stridsbergers. You'll need to reduce the signal to get a total of max 5-6dB from amp thru splitters so add a fixed attenuator before the splitter. You probably don't need FM trap filters but it doesn't hurt to add one before the splitter.

Stridsbergs multicouplers have something like 2-3dB as a noise figure at best and adding a low noise amp before it will make your antenna almost double its sensitivity.

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/Ubbe

 

[kruser]

I bought one of the 16 port DLI models quite a while back.
They do work but I noticed issues with it destroying weaker digital signals. It seems the amp chip they use has a higher noise figure than what an 8 port Stridsberg has. That was enough to kill any chance at locking on and decoding control channel data on signals that had a marginal signal strength to begin with.
I also found that the output on the DLI is not flat, it probably has 5 or 6dB of gain over the input. I tried attenuating that back down to zero for the digital signal problem but that did not help.
I forget what make and model the RF transistor is in the DLI but I think it had two if I remember correctly. I think they split the signal with a passive splitter at its input and then fed the two RF amp stages which fed the same model of mini-circuits splitters that are used inside Stridsberg products.
Either way, the overall gain was slightly higher than it should have been. I'd have preferred to see a flat gain level between input and output.

I ended up keeping the 16 port DLI coupler and use it for a bunch of old receivers only. Old crystal models for example. It works well for that application.

As far as daisy chaining two 8 port Stridsberg's, I'd not do that unless you are going to feed just analog radios. I tried it and ran into the same issue as the DLI where any digital radios hooked to the 2nd Stridsberg had issues decoding data.
I never checked weak analog signals for added noise when used in a daisy chain configuration but it was probably there.

Something like what @prcguy is suggesting would be the way to go. You could use a 2-port 'passive' splitter from Stridsberg to feed two of prcguy's setup. The passive splitter before each 16 port module would give you a 3dB or so loss but with the amp prcguy is suggesting, that loss would be made up for.
The only thing I see about prcguy's amp choice is its noise figure. It's kind of high plus it looks like the NF really jumps up when it gets to its low end at 50 MHz. If you are going to use this design for low band below 50 MHz, a different amp would be better.

 

[buddrousa]

I have a 4 port Stridsberg feeding 2 8 port stridsbergs in my 16 scanner rack and the other 2 ports of the 4 port feed my new cross country wireless 5 port feeding a 4 scanner test setup and 1 SDS100 handheld with no interference.
Cross Country Wireless - radio equipment manufacturer and radio engineering consultants NOTE there was over a 30 day order to delivery on mine but it was Christmas.

 

[blantonl]

Yea, I've also gone the route of chaining Stridsberg multi-couplers with excellent success. I have one 8 port model that functions as my "root" hub and splits off to 3 other 8 port models. Any of my high end receivers that I absolutely cannot tolerate a loss of DB or doubling of the noise floor go off the root multi-coupler. The other 3 multi-couplers are for various scanners, SDRs for feeds etc.

This setup from my primary rooftop antenna gives me (8x4)-3 ports, or 29 usable ports. 24 for various radios and feeds, and 5 for all the high-end radios (Icom R9500, Icom R8600, AR5000, Winradio EXCELSIOR, and a switch to my desk)

 

[cg]

The DLI may be out of production by now. I had a repair done to the 2 I have and they indicated they would not be making any more. I found the unit to be very sensitive to static damage. I would realize that I lost that bit of amplification and now had attenuation.
I called Stridsberg regarding daisy chaining them and they recommended only putting one in sequence. In other words, don't put three in a row, instead do as the others described here, feed several multicouplers from several ports of one multicoupler.
I have found the performance of the 700/800 is not great with the Stridsbergs but I am always dealing with moderate to weak signals. Also, the 800 MHz units are too tight to catch 700MHz. At the time I talked to them several years ago, they had stated they were going to make a 700 unit but not a combo 700/800 unit. I have not seen the 700MHz unit though.

chris

 

[prcguy]

The noise figure of the specific MiniCircuits amp I chose is a little higher than I would like but its fine, your local noise floor is probably high enough where the amps NF will get lost in actual use. I don't find any amplifiers from MiniCircuits that have a lower noise figure AND similar IP1/IP3. That is much more important in a high signal environment.

The slightly high noise figure of the ZHL-2010 is a constant and it has a high IP1 of around 30dBm (1 watt!) and its IP3 of 46dBm will make a predictable multicoupler. An amp like the MiniCircuits ZX60-P103LN that some have recommended on RR over the years with its IP1 around 22dBm and IP3 around 39dBm can and will overload and create lots of IMD making your multicoupler unpredictable. At least it does at my house. Anyone want to buy some new ZX60-P103LNs cheap??

The mini-circuit amp have an extremely good high signal overload performance that probably are not neccesary for indoor antennas. It also has a bad noise figure of almost 4dB. Their splitter are focused at having low phase shift and perfectly balanced attenuation for all ports, only really neccesary when doing measurements and equal lab works.

I would suggest a low noise amp, less than 1dB, with good IP3 of 40dBm and then a 1-4 splitter to feed your stridsbergers. You'll need to reduce the signal to get a total of max 5-6dB from amp thru splitters so add a fixed attenuator before the splitter. You probably don't need FM trap filters but it doesn't hurt to add one before the splitter.

Stridsbergs multicouplers have something like 2-3dB as a noise figure at best and adding a low noise amp before it will make your antenna almost double its sensitivity.

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/Ubbe

 

[N9JIG]

Since I have the MC's already I have set up my 4-port wide-band Stridsberg as the root device connected to the antenna feed line in the cabinet. I then have the 2 8-port wide-band MC's and the 800 MHz. 4-port connected to the root device's outputs. I have one spare port for now, but I might try that on the R8500 later on but for now it is empty.

So far it seems to work well on the local NWS channels as well as the local ATIS stuff. I will see how well it compares with my prior reception experience.

I have spoken to Stridsberg in the past about a larger capacity multicoupler and it was on his project list but he made no promises. I have found that my MCA804 works fine on the 700 MHz. band, at least the signal strength and apparent voice quality seems to match that of the antenna connected directly to the radio, if not actually a little better.

I might still look into making my own system with an amp and splitters. I want to evaluate this first before I spend the money.

 

[N9JIG]

So last week I set up the existing multicouplers, using the 4-port Stridsberg as the root unit connected to the antenna. This feeds 2 8-port Stridsbergs, which then go to the Uniden scanners (8 BCT15's, 4 BCT15X's and 4 BCD996XT's). It also feeds a 4-port 800 MHz. Stridsberg which serve 4 PSR600's that follow the local trunked systems. The 4th port goes to my R8500 but if needed can be used for a 4th daughter multicoupler in the future.

I do have another 8-port Stridberg currently used for the desktop radios in case I want to use it as the root device instead of the 4-port but for now it all seems to be fine the way it is.

I did a comparison of relative indicated signal strength on a couple of the Unidens as well as the R8500, and also compared voice quality and noise floor indices. I used the R8500 for most of the testing since I trust the relative signal strength indication more than the bar graph on the Uniden scanners.

The indicated noise floor was slightly higher with one multicoupler than with the antenna connected directly to the radio on most freqs, and slightly higher still when ran thru two multicoulplers. I saw no difference when trying various combinations of the 4 wideband Stridsbergs I have in different orders (Root/daughter) to see if I would get better results with one specific multicoupler as the root. I was unable to see any difference with any one of the 4 as the root device.

So far I am very happy with the results, I was able to utilize the best of my scanner antennas for 20 scanners and can scale up to 64 scanners if needed in the future. I don't see that being needed but one never knows!

I think this is going to be the solution for now, at least until I can improve my antenna solution here or in a new home.

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• N9JIG
• Jan 28, 2020

Stacking Multicouplers