Yet Another Multicoupler Thread

[Kiniutech]

Hi, Dumb question. I am using Eletroline EDA 2400 splitter for 3 scanners + SDR's
Also, recently I acquired Nooelec Flamingo FM Filter. At the moment filter is connected to Air-Spy 2 SDR feed alone (after Splitter)
Question, can I move FM filter Before the splitter to filter all 3 feeds or buy additional filters for each scanner?

 

[sonm10]

Hi, Dumb question. I am using Eletroline EDA 2400 splitter for 3 scanners + SDR's
Also, recently I acquired Nooelec Flamingo FM Filter. At the moment filter is connected to Air-Spy 2 SDR feed alone (after Splitter)
Question, can I move FM filter Before the splitter to filter all 3 feeds or buy additional filters for each scanner?

FM broadcast filter should come before the splitter

 

[Kiniutech]

Thank you, as I expected it may be the case but I wasn't 100% sure.

 

[yellingsoftly]

Been thinking through this and I haven't been able to get Stridsbergeng. to respond. Maybe just swamped but makes me nervous. Thinking I may just take a zhl-1010 preamp and then a ZCSC-8-13-S+ 8 port minicircuits splitter. I already have an noolec 20db lana wideband lna and fm notch filter right next to the antenna that seems to work really well so just a preamp to overcome the loss of the splitter and no more would probably be good to not increase noise. Any issues with this plan? I'll probably have 6 sdr's running off this.

 

[prcguy]

Been thinking through this and I haven't been able to get Stridsbergeng. to respond. Maybe just swamped but makes me nervous. Thinking I may just take a zhl-1010 preamp and then a ZCSC-8-13-S+ 8 port minicircuits splitter. I already have an noolec 20db lana wideband lna and fm notch filter right next to the antenna that seems to work really well so just a preamp to overcome the loss of the splitter and no more would probably be good to not increase noise. Any issues with this plan? I'll probably have 6 sdr's running off this.

I would avoid cascading preamps and 20dB gain on the noolec for a single preamp is generally too much for a low performing amp. Using just the ZHL-1010 feeding an 8-way divider will give you basically unity gain at all ports. You could use a ZHL-2010 with 20dB gain and a 6dB attenuator on the output giving about 4dB gain per port which is about the most I would recommend.

 

[yellingsoftly]

I would avoid cascading preamps and 20dB gain on the noolec for a single preamp is generally too much for a low performing amp. Using just the ZHL-1010 feeding an 8-way divider will give you basically unity gain at all ports. You could use a ZHL-2010 with 20dB gain and a 6dB attenuator on the output giving about 4dB gain per port which is about the most I would recommend.

Ok hmm, this is all hooked to a no gain radioshack discone mostly for airband stuff. The noolec makes a huge difference provided the notch filter is there (before the fm notch aweful) as I have 70ft or so run of lmr400 so without it I just hear so much less. Was just trying to split it off so I could record more airband frequencies at once for research plus some acars/vdml2 stuff. Didn't want to lose the gain I already had. Here's what the nooleec lana specsheet says.


+20dB of RF gain at 1000MHz
0.9dB noise figure at 1000MHz

 

[prcguy]

Ok hmm, this is all hooked to a no gain radioshack discone mostly for airband stuff. The noolec makes a huge difference provided the notch filter is there (before the fm notch aweful) as I have 70ft or so run of lmr400 so without it I just hear so much less. Was just trying to split it off so I could record more airband frequencies at once for research plus some acars/vdml2 stuff. Didn't want to lose the gain I already had. Here's what the nooleec lana specsheet says.


+20dB of RF gain at 1000MHz
0.9dB noise figure at 1000MHz

Those are just two parameters. What about 1dB compression (IP1) or third order intercept IP3? Those numbers on the ZHL amps are really good but the nooelec probably sucks. The nooelec preamp as about $35 and the MiniCircuits is $190, you get what you pay for.

And preamp gain is not a substitute for antenna gain, two different things with two different outcomes and too much preamp gain
is not so good.

 

[Pape]

Been thinking through this and I haven't been able to get Stridsbergeng. to respond. Maybe just swamped but makes me nervous. Thinking I may just take a zhl-1010 preamp and then a ZCSC-8-13-S+ 8 port minicircuits splitter. I already have an noolec 20db lana wideband lna and fm notch filter right next to the antenna that seems to work really well so just a preamp to overcome the loss of the splitter and no more would probably be good to not increase noise. Any issues with this plan? I'll probably have 6 sdr's running off this.

That is a lot of amplification. Did you try to pad the current setup and see if you really need all that much amplification ?
I also run a lana + flamingo on a dicone over 75' LMR 400 on an ZFSC-8-43+. I can pad the analog signal for 3 DB without lost in the 100~200 MHZ. The estimated db at that frequency is 10 DB without the -3 DB.

 

[yellingsoftly]

That is a lot of amplification. Did you try to pad the current setup and see if you really need all that much amplification ?
I also run a lana + flamingo on a dicone over 75' LMR 400 on an ZFSC-8-43+. I can pad the analog signal for 3 DB without lost in the 100~200 MHZ. The estimated db at that frequency is 10 DB without the -3 DB.

Thanks for sharing that is my setup exactly, I guess I'm still new to this and learning. I haven't tried padding the signal. What are you using to pad the signal and dumb question how do you know when to pad the signal vs not? I do also listen to mil air bands in the 300mhz as well if thats relevant.

 

[Pape]

So you are running the ZFSC-8-43+ currently or looking a adding one ?
I use a attenuator kit

 

[yellingsoftly]

So you are running the ZFSC-8-43+ currently or looking a adding one ?
I use a attenuator kit

Looking to add one, currently just running one rtl-sdr v4 but planning to add an sdrplay rsp1b and some more rtl-sdr's. So you run 3 attenuator's from that kit for -3DB?

 

[Pape]

Currently I run without any padding.
Let say I did the permutation test, from: original, antenna coax and my main receiver to all the equipment, Ant -> filter -> lna -> coax -> bias-tee -> spliter -> receiver.
I found out that adding -3 DB to the line before the ZFSC-8-43+ did lower my signal but the voice quality remained virtually the same, at -6 I was earing degradation on the week signal and so on. Since the -3 db did not remove any negative (some small interference) I decided to keep it simple and remove it.

This is a portion of my spreadsheet to give you a idea

MHZ	100​	200​	300​	400​
Coax	0.95​	1.35​	1.65​	1.91​
Spliter	9.84​	9.93​	9.96​	10.06​
Patch	1​	1​	1​	1​
Lost	11.79​	12.28​	12.61​	12.97​
LANA	22​	22​	22​	22​
total	10.21​	9.72​	9.39​	9.03​

My personal advice is just add the ZFSC-8-43+ and if you find it to have a lost of quality than start looking at LNA.

 

[prcguy]

Looking to add one, currently just running one rtl-sdr v4 but planning to add an sdrplay rsp1b and some more rtl-sdr's. So you run 3 attenuator's from that kit for -3DB?

You put one attenuator after the preamp and before the splitter to provide 0 to maybe 4dB of gain at each port of the splitter.

 

[yellingsoftly]

Currently I run without any padding.
Let say I did the permutation test, from: original, antenna coax and my main receiver to all the equipment, Ant -> filter -> lna -> coax -> bias-tee -> spliter -> receiver.
I found out that adding -3 DB to the line before the ZFSC-8-43+ did lower my signal but the voice quality remained virtually the same, at -6 I was earing degradation on the week signal and so on. Since the -3 db did not remove any negative (some small interference) I decided to keep it simple and remove it.

This is a portion of my spreadsheet to give you a idea

MHZ	100​	200​	300​	400​
Coax	0.95​	1.35​	1.65​	1.91​
Spliter	9.84​	9.93​	9.96​	10.06​
Patch	1​	1​	1​	1​
Lost	11.79​	12.28​	12.61​	12.97​
LANA	22​	22​	22​	22​
total	10.21​	9.72​	9.39​	9.03​

My personal advice is just add the ZFSC-8-43+ and if you find it to have a lost of quality than start looking at LNA.

Ok thanks appreciate the advice and the spreadsheet. That gives me some ideas.

 

[yellingsoftly]

You put one attenuator after the preamp and before the splitter to provide 0 to maybe 4dB of gain at each port of the splitter.

Ok thanks, I'll keep that in mind. May try without and add as needed.

 

[Ubbe]

Hi, Dumb question. I am using Eletroline EDA 2400 splitter for 3 scanners + SDR's
Also, recently I acquired Nooelec Flamingo FM Filter. At the moment filter is connected to Air-Spy 2 SDR feed alone (after Splitter)
Question, can I move FM filter Before the splitter to filter all 3 feeds or buy additional filters for each scanner?

The Electroline devices are designed to handle huge signals from TV and Radio broadcasters, so it will not need any filters, as much as your receivers will, but to save money you put it on its input. That Flamingo are stated at max 0,9dB passband loss so that small amount are not noticeable.

/Ubbe

 

[Pape]

Ok thanks, I'll keep that in mind. May try without and add as needed.

Depending on what you wish to do.
If your goal is to remove FM band for all connected device you put it before the amp. Also make the filter more effective as it does not need to fight the added DB from the amp on that band, if any. I did not look at the spec. If you have any LNA, I would say before the LNA also
If you want to maintain one port with all band at full than, you will need to put one per port you wish to filter the FM band out.