Yet Another Multicoupler Thread

[KC1UA]

This spring I plan a revamp of my tower mounted antennas. In advance of that, based on a lot of info gathered from RR, combined with the apparent unfortunately slowdown at Stridsberg Engineering, I've decided that going forward I'm going to build my own multicouplers. As has been hashed and re-hashed here with the right parts they can be built for less than the cost of the Stridsbergs and perhaps with better results.

With some of the suggestions of @prcguy and @Ubbe (and my thanks) I've been watching eBay for various devices. I had already built one 8 port multicoupler as outlined in this thread , using a PGA-103+ amp and the results have been very good. I've been looking for one of the ZHL-1010's that were mentioned in that thread. Last week I found one, albeit a 75 ohm version, and decided to give it a whirl anyway. This is the model I'm referring to. It appeared to me to have similar specs to the 50 ohm model that has SMA connectors. On its input I have a HPN-30118 30 MHz high pass/88-108 notch filter. From the output a short BNC to F cable feeds an 8 port Amphenol coaxial splitter. I'm not using the Mini Circuits 8 port splitter as referenced in my original thread as I simply couldn't find the correct one (yet) and the Amphenol splitter seems to work quite well on the PGA-103+ model I built. I don't like having to convert from F male to BNC female though so I'll continue to look for the Mini Circuits splitters. That said, on paper this "seems" to be a good balance as the overall gain of the ZHL-1010-75 is roughly 11dB across its coverage and the Amphenol splitter states -11dB out at each of its ports. All I am trying to do is overcome the loss from splitting a signal; I'm in no need of any amplification in my semi-heavy RF area. I am powering the amp from my 12VDC linear power supply system (Astron RM35A).

Thus far it appears to me to be working as well, if not better than, my Stridsberg MCA208. The ZHL-1010-75 cost me roughly $50 shipped via eBay, the splitter another $20, and I already had the filter and coax on hand. Hopefully I'll be able to find a few of the Mini Circuits splitters in question and implement them instead.

Pretty easy project, and IMHO a prudent one given the unknown future of Stridsberg. I realize the sad circumstances that may be causing them some issues. I also reached out to Cross Country Wireless twice by email about their 5 port multicoupler but never received a reply. Maybe they're no longer in business.

If you're going to try this and want the Mini Circuits splitter, you will see numerous options on eBay but the one you want is the one in the other thread, which shows the labeling of "Mini Circuits 15542 ZFSC-8-43" on the case. There are others that look exactly like it but the fine print indicates a high end of 175 MHz, or 300 MHz, obviously far below the needs of those of us in this hobby, for the most part anyway. The correct one is good to 1 GHz.

 

[Pape]

The never ending cycle of setup improvements 😉
Not sure this project is on 5 years cycle lol

 

[prcguy]

This spring I plan a revamp of my tower mounted antennas. In advance of that, based on a lot of info gathered from RR, combined with the apparent unfortunately slowdown at Stridsberg Engineering, I've decided that going forward I'm going to build my own multicouplers. As has been hashed and re-hashed here with the right parts they can be built for less than the cost of the Stridsbergs and perhaps with better results.

With some of the suggestions of @prcguy and @Ubbe (and my thanks) I've been watching eBay for various devices. I had already built one 8 port multicoupler as outlined in this thread , using a PGA-103+ amp and the results have been very good. I've been looking for one of the ZHL-1010's that were mentioned in that thread. Last week I found one, albeit a 75 ohm version, and decided to give it a whirl anyway. This is the model I'm referring to. It appeared to me to have similar specs to the 50 ohm model that has SMA connectors. On its input I have a HPN-30118 30 MHz high pass/88-108 notch filter. From the output a short BNC to F cable feeds an 8 port Amphenol coaxial splitter. I'm not using the Mini Circuits 8 port splitter as referenced in my original thread as I simply couldn't find the correct one (yet) and the Amphenol splitter seems to work quite well on the PGA-103+ model I built. I don't like having to convert from F male to BNC female though so I'll continue to look for the Mini Circuits splitters. That said, on paper this "seems" to be a good balance as the overall gain of the ZHL-1010-75 is roughly 11dB across its coverage and the Amphenol splitter states -11dB out at each of its ports. All I am trying to do is overcome the loss from splitting a signal; I'm in no need of any amplification in my semi-heavy RF area. I am powering the amp from my 12VDC linear power supply system (Astron RM35A).

Thus far it appears to me to be working as well, if not better than, my Stridsberg MCA208. The ZHL-1010-75 cost me roughly $50 shipped via eBay, the splitter another $20, and I already had the filter and coax on hand. Hopefully I'll be able to find a few of the Mini Circuits splitters in question and implement them instead.

Pretty easy project, and IMHO a prudent one given the unknown future of Stridsberg. I realize the sad circumstances that may be causing them some issues. I also reached out to Cross Country Wireless twice by email about their 5 port multicoupler but never received a reply. Maybe they're no longer in business.

If you're going to try this and want the Mini Circuits splitter, you will see numerous options on eBay but the one you want is the one in the other thread, which shows the labeling of "Mini Circuits 15542 ZFSC-8-43" on the case. There are others that look exactly like it but the fine print indicates a high end of 175 MHz, or 300 MHz, obviously far below the needs of those of us in this hobby, for the most part anyway. The correct one is good to 1 GHz.

You could take it one step further and place the FM filter and amplifier at the antenna leaving only the splitter at the radios. That would improve system noise figure by roughly the amount of feedline loss you have.

 

[KC1UA]

Good idea. I've looked at some enclosures for doing that with an Advanced Research pre-amp for an 800 yagi I'm considering.

@prcguy, are you familiar with the ZFSC-82-75 splitter? As far as I can tell it's good to 900 MHz which in many cases would work for me. I do have some 900 MHz DMR systems I monitor but use a dedicated antenna for it so not an issue. Wonder if that splitter is a viable alternative. I don't see anything telling me it isn't necessarily but I defer to those that know more than me.

 

[prcguy]

Good idea. I've looked at some enclosures for doing that with an Advanced Research pre-amp for an 800 yagi I'm considering.

@prcguy, are you familiar with the ZFSC-82-75 splitter? As far as I can tell it's good to 900 MHz which in many cases would work for me. I do have some 900 MHz DMR systems I monitor but use a dedicated antenna for it so not an issue. Wonder if that splitter is a viable alternative. I don't see anything telling me it isn't necessarily but I defer to those that know more than me.

I don't have much faith in ARR preamps, they tend to be low IP1 and IP3. Ok specs for the 1970s but not today. The splitter is 75 ohms and should work into the mid 900 range with slightly reduced specs.

 

[rgchristy]

I've been wondering about this topic. There are numerous threads and suggestions on homebrew multicouplers.

Would it be possible for the experts here to come up with "general consensus" homebrew four and eight port multicouplers, that could be either posted as a sticky in this forum or in the Wiki?

If it could include parts lists, links, instructions, that would be fantastic!

 

[Ubbe]

Multicoupler isn't a good solution to use. It's much better having a separate amplifier at the antenna, powered either by a separate cable or by the coax and a bias-T, and have a passive splitter at the receivers and then some attenuation to lower the level into the splitter to get the best signal/noise ratio for each receiver. Filters can be added for FM broadcast, pagers and cellular or for other interfering strong transmitters.

Amplifiers usually have less gain at 900Mhz compared to 100Mhz and receivers like scanners are often overloaded more easily at lower frequencies, so some kind of equalization are recommended, just a capacitor of a couple of pico farad might do it in series with the signal perhaps soldered inside the splitter or attenuator.

When having the amplifier at the antenna it will work as a buffer, loading the antenna with an almost constant impedance and also loading the coax with a constant impedance. The same happens with a splitter that it will isolate each receiver from the coax and load the coax with a constant impedance as well as each receiver/scanner.

/Ubbe

 

[KC1UA]

I'd like to steer clear of amplification altogether if possible but I understand the amp at the antenna concept, absolutely. In this case I was simply trying to duplicate the performance of commercially available multicouplers and feel like I did so successfully. My location in relation to strong RF sources in my opinion minimizes amplifying anything. The exception was what I was mentioning above with the amplifier that prcguy pretty much talked me out of. I have one distant 800 MHz system I'd like to try to receive but haven't had a lot of success. I figured a good sized 800 MHz yagi with an amp in an enclosure at the antenna might get me over the hump. I did find this one from Mini Circuits that appears to my relatively uneducated brain that it could be a reasonable choice.

At some point I may experiment with your suggestion Ubbe, once my New England winter (mild overall as it has been) passes, that's when some antenna changes will be made here. It's easy enough for me to run some voltage up the tower and power an LNA so might be worth a try.

I like the Wiki page idea for these roll your own multicoupler projects as well.

 

[cg]

Do you still have your Digital Logger 16 port splitter? I had been thinking about removing the electronics out of mine and using it for a homebuilt splitter as the manufactured version was extremely prone to component failure. I have two of them and would set them both up if it is reasonable.

 

[KC1UA]

Do you still have your Digital Logger 16 port splitter? I had been thinking about removing the electronics out of mine and using it for a homebuilt splitter as the manufactured version was extremely prone to component failure. I have two of them and would set them both up if it is reasonable.

Sold that one a long time ago, Chris. I was never happy with it and always questioned its performance. Too bad; I loved the rack mount capability of it. I bet you could gut it and build a far better one using the housing. They've since gone out of business as far as I recall.

 

[fxdscon]

They've since gone out of business as far as I recall.

They're still up and running, I purchased a couple of items from their website a short time ago. They still show a page for the multicoupler, but the link to purchase one is a dead end.

Wideband RF Multicoupler - 16 Radios, Surge Protected, 50 Ohm

16 Port Active RF Multicoupler, ships now, free trial

www.digital-loggers.com

 

[KC1UA]

They must have never removed the page; no links to it from their product pages either. Thought about it further, I actually wound up sending my first one back to them as it was not working properly. They were great about it and quickly provided a replacement, but I just never found it to work on a par with the Stridsbergs I had/have.

I found some of the Mini-Circuits ZFSC-82-75 8 way BNC splitters and ordered them, so I'll replace the CATV connectors I'm currently using with them once they arrive.

 

[rgchristy]

Rather than hijack this thread, I'm going to start a new thread with my situation to see what would work best.

 

[KC1UA]

If anyone is interested there are some ZHL-2010+ LNA's available. I just purchased one; 6 left.

Mini-Circuits ZHL-2010+ Low Noise Amplifier Used *Very Nice Condition* | eBay

<p>Mini-Circuits Low Noise Amplifier ZHL-2010-46P3 (SMA), 50-1000MHz, 12v. </p><p>Used, in very nice condition. </p><p>7 available.</p>

www.ebay.com

 

[prcguy]

If anyone is interested there are some ZHL-2010+ LNA's available. I just purchased one; 6 left.

Mini-Circuits ZHL-2010+ Low Noise Amplifier Used *Very Nice Condition* | eBay

<p>Mini-Circuits Low Noise Amplifier ZHL-2010-46P3 (SMA), 50-1000MHz, 12v. </p><p>Used, in very nice condition. </p><p>7 available.</p>

www.ebay.com

The 2010 has a lot of gain and the 1010 is more suited for feeding a 4-way or 8-way divider. The more gain the LNA has the more problems you can have at lower RF levels.

 

[KC1UA]

Understood. The spec's show roughly 22 dB of gain across its coverage, and my 8 ways have I believe about 11 dB loss at their outputs. If I pad the input of the splitter I would think that would help? This won't be a front-line solution anyway but for the el-cheapo price I figured I'd grab one. I haven't seen any of the 1010's yet (there are a few from China but definitely not going there as they're overpriced and probably knock-offs) but I have an auto-search going for them.

 

[prcguy]

Understood. The spec's show roughly 22 dB of gain across its coverage, and my 8 ways have I believe about 11 dB loss at their outputs. If I pad the input of the splitter I would think that would help? This won't be a front-line solution anyway but for the el-cheapo price I figured I'd grab one. I haven't seen any of the 1010's yet (there are a few from China but definitely not going there as they're overpriced and probably knock-offs) but I have an auto-search going for them.

Yes you can pad the amp output/splitter input to set the system gain and that's ok to a point. You are juggling LNA parameters giving up precious noise figure for higher IP1 and IP3 specs to help survive in a busy RF environment. Increasing gain beyond what you need to make up for splitter loss only goes toward pushing the LNA into an IMD generator earlier.

If you have some filtering before the LNA like a good FM trap and/or high pass low pass to keep out local strong cell towers, TV stations, etc, that will all help keep the LNA happy.

 

[KC1UA]

It'll definitely at the very least have an FM trap in front of it. I have been using the HPN-30118's which seem to do a decent job but was also looking at these: https://www.minicircuits.com/pdfs/ZBSF-95+.pdf FM Broadcast and a very strong Con+ control channel that alternates between a 461 and 463 MHz frequency are my #1 enemies. I've found that a decent FM trap works wonders and I just work around the CC.

The 1010 75ohm model I found a few weeks ago is working very nicely. I'm hoping to find more of those in either 75 or 50 ohm form. The 2010 will be a backup in the event another multicoupler craps out. I'm becoming skeptical of my 8 port Stridsberg. I also want to take one of them and place it at/near an antenna and feed it directly to the splitter (with filters) and see how that works. Just need some warm weather; it was warmer in late February than it is now. Typical New England early spring.

Thanks as always for your knowledge and input.

 

[prcguy]

It'll definitely at the very least have an FM trap in front of it. I have been using the HPN-30118's which seem to do a decent job but was also looking at these: https://www.minicircuits.com/pdfs/ZBSF-95+.pdf FM Broadcast and a very strong Con+ control channel that alternates between a 461 and 463 MHz frequency are my #1 enemies. I've found that a decent FM trap works wonders and I just work around the CC.

The 1010 75ohm model I found a few weeks ago is working very nicely. I'm hoping to find more of those in either 75 or 50 ohm form. The 2010 will be a backup in the event another multicoupler craps out. I'm becoming skeptical of my 8 port Stridsberg. I also want to take one of them and place it at/near an antenna and feed it directly to the splitter (with filters) and see how that works. Just need some warm weather; it was warmer in late February than it is now. Typical New England early spring.

Thanks as always for your knowledge and input.

I just looked in my future project box and it looks like I need to put a few multicouplers together or do something with all these amps. I found three ZHL-1010s, two ZHL-2010s and a 75 ohm ZHL-1010. Plus a spare ZBSF-95 FM trap and some RF limiters. I don't really need a multicoupler at this time but I can mount a ZHL-1010 and the 10MHz to 1GHz 8-way divider to a small aluminum plate with an RF limiter and FM trap in front of the amp and maybe make it available to people for testing to see if the design works ok in their area.

 

[Pape]

this is one heck of a rabbits hole