Single antenna to multiple receivers (RX Only)

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I am looking to setup a single antenna to multiple receivers. If I can avoid having to switch to each receiver that would be nice.

Can I simple just spread the feed across the receivers or do I need a magic box of tricks to sit between the antenna and receivers

Cheers
John

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Is it just for receiving, John? If for transmitting you will probably need the isolation of a coaxial switch. I am working the other way around, multiple antennas to a single transceiver, and a co-axial switch does the job for me.

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The article in in German but it describes how to create an RX antenna distribution system with impedance match.

You can use in online translator to convert to English but the shematics are univeral.

Page 10 and 11 for RX only.

What is available is an automated box (SDR Coax Relais) to connect one transmitter and one (or multiple RX like an SDR) to one antenna.
Everything else is a job for a coax switch with something like a “station master controller” to manage that.
Otherwise you will fry your RX stages of the other radios.

73 Joe

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Hi, yep just for RX only. APRS and maybe ADSB via one scanner antenna to see if reception improves as the APRS and ADSB are both in the loft at the mo, and then scanner antenna is outside
Cheers
john

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In my far-off SWL days I found a simple rotary switch would suffice, in fact initially with just two receivers I used a 2 pole 2 way toggle switch successfully. I found connecting the receivers in parallel without a switch causes noticable losses.

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Hi M0VAZ,

For HF, I am using the MFJ 1708 SDR receiver T/R switch. This allows me to split my HF antenna between my rig and my SDRPlay RSPdx, which feeds my N1MM band scope. Cost me around $130 last week at HRO.

There is also this site, which makes some serious gear. http://www.stridsbergeng.com/multicouplers.html

Their multicouplers are designed for various bands, HF, VHF/UHF, 800/900mhz, VLF/LF, etc. These are the quality you’d see in professional/military type setups.

Here is a link to a Reddit post from 11 months ago discussing this very topic (and where I got my product recommendations from): https://www.reddit.com/r/amateurradio/comments/z11gsx/are_cheap_tv_amps_of_any_potential_use_to_a_ham/ixgst2e/?context=3

Here’s a video from two years ago from a ham in Canada using old TV splitters to feed 15 radios from one antenna: https://www.youtube.com/watch?v=1dccjqw0sJ4&list=WL&index=13

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Cheers. Frugal Radio certainly likes his SDRs and scanners ! :slight_smile:

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Chris G4HYG makes “multicouplers”: Cross Country Wireless HF/VHF/UHF Multicoupler
He’d probably do you a custom version on request.

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Thanks.

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Hi John,
For receive only, just connect rhe feeds together.
You will incur at least a 3dB loss per additional rx. This probably does not matter, but uhf in parallel with hf may be problematic.
Next option is a simple broadband preamp between the ant and the RX’s.
Receiver impedance matching is not an issue but linearity as always is.
Long ago, monitoring stations used a preamp consisting of banks of 807 valves to retain the linearity.
David

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That he does! Definitely gave me inspiration when I was designing my scanner setup back in the day. Got into HF radio at the same time and HF won out. :slight_smile:

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This is the “right” way in that it will preserve the impedance properly if that is a concern. Basically a transformer with two separate output coils with proper turns ratios and a matching resistor.
An example device:

More info:

There are TONS of these for 75 ohms lying around (for cable!)

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Thanks KM6AM more reading.

Cheers
John
M0VAZ

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Hi John.
I have one HF transmitter in my shack in the basement and one in the sitting room. They both use the same multiband vertical HF antenna on the roof of my house. When I am in the shack I always turn on the light, and the same switch turn on the 12v power supplying everything 12V in the shack. The 12V supply two car type relays (switching between two poles) one for each transmitter, so that when the light is on, the transmitter in the shack is connected to the antenna, and the transmitter in the sitting room is connected to ground. When the light is off it is opposite. I was afraid that one transmitter may ruin the first amplifier steps in the other transmitter, but I have not noticed any problems yet. Good luck. 73 LA6FTA Gudleik.

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