Passive splitter

[sgnlsekr]

I am still buying equipment but the goal is to have a Diamond D130 up on the chimney and feeding 2-4 dongles via 50 feet of LMR400 coax. I was looking that the specs of a splitter here: https://www.datasheets.com/en/part-details/zfsc-4-1--mini-circuits-20216050 I live fairly close to most of the important transmitters. Would the published loss of the splitter be acceptable in your opinion?

 

[chief21]

According to the spec sheet, that splitter provides a loss of over 6dB to each port... That means that each port will actually receive less than one-quarter of the original signal. Not very good!
What you probably should be using is a receive multi-coupler. These devices typically provide enough low-noise amplification to compensate for the loss to each port.

 

[wtp]

if they are that close, you might do better with the back of the set for some freqs in a radio,
and then use an outside one for the hard to get ones.

 

[N6SPP]

I am still buying equipment but the goal is to have a Diamond D130 up on the chimney and feeding 2-4 dongles via 50 feet of LMR400 coax. I was looking that the specs of a splitter here: https://www.datasheets.com/en/part-details/zfsc-4-1--mini-circuits-20216050 I live fairly close to most of the important transmitters. Would the published loss of the splitter be acceptable in your opinion?

Hi- ok on the ~6dB loss.. Right: 1/2 (3dB) and another 1/2 (3dB) of the orig sig level @the feedpoint and another ~2dBish in the LMR run.. A 6dB loss is roughly a single S unit. If the original received sig is S7, after a ~6dB loss, the sig would be ~ S6. So this is dependent partly on the orig rcv'd sig @ the D130's (unity gain) feedpoint. I suppose the rf pigtail jumper into each sdr would see this evenly (freq dependent). If necessary, I suppose you might be able to insert a low noise amp near the feedpoint and feed it with bias dc in the LMR run after the splitter (which likely blocks dc). Probably the safest thing to do is attach the coax to the D130 and run direct to the splitter on the operating desk w/out using an inline amp. Compare a steady sig like a 162MHz NOAA stn- with the splitter in and out of the circuit. 73,n6spp-cm98

 

[G7RUX]

I am still buying equipment but the goal is to have a Diamond D130 up on the chimney and feeding 2-4 dongles via 50 feet of LMR400 coax. I was looking that the specs of a splitter here: https://www.datasheets.com/en/part-details/zfsc-4-1--mini-circuits-20216050 I live fairly close to most of the important transmitters. Would the published loss of the splitter be acceptable in your opinion?

Each output being 6dB down on the input is the absolute best you could expect here since you are splitting the power four ways; you’ll get a quarter at best at each output. An extra half dB or so is pretty good (MiniCircuits gear is generally very good) so you’ll likely get perfectly good performance from this setup.

You could use a 10 dB head amplifier to compensate for the splitting and cable losses and that shouldn’t be problematic, although strong signals could be an issue if you are close to transmitter sites, especially those that you don’t want to receive.

In short, it should be fine.

 

[Ubbe]

I am still buying equipment but the goal is to have a Diamond D130 up on the chimney and feeding 2-4 dongles via 50 feet of LMR400 coax. I was looking that the specs of a splitter here: https://www.datasheets.com/en/part-details/zfsc-4-1--mini-circuits-20216050 I live fairly close to most of the important transmitters. Would the published loss of the splitter be acceptable in your opinion?

That splitter are $125 plus shipping. Get a $10 CATV 75 ohm splitter that will only add an additional 0,4dB loss due to impedance mismatch and equal to zfsc-4 with its other specs.

Look at the signal levels you have now, if it can handle a 10dB reduction in level. You would want all your received signal to be stronger than -90dBm and will need an amplifier if your important frequencies are weaker than that when you add a 10dB loss. You can also combine splitters, one 1-2 to only get a 4dB reduction to one receiver and then to the other output you connect a 1-2 or 1-3 splitter for receivers that only receives stronger signals. There's even tap splitters where one output have something like a 2dB loss and 8dB from the others.

/Ubbe