RF Splitters & Combiners - How do they work?
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- čas přidán 8. 08. 2023
- This video explains how a Hybrid RF Splitter / Combiner works. The main purpose of this device is to split or combine an RF signal while providing high isolation between ports and good impedance matching to 50 ohms. This design is commonly used with LDMOS and other high powered amplifiers. The splitter can take a single signal source and use it to drive 2 or more RF boards while the combiner can take the signal from 2 or more RF boards and combine their power output. This video also shows how to make insertion loss, isolation, and SWR measurements using a NanoVNA.
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Great walk-thru and description!
Thanks!
73...
great content again!
Wow. Great walk thru. Answered questions I had on auto transformers and using coax in a transformer. Subscribed and will be going over you other videos. Very well done!
Thanks for you positive feedback!
GREAT INFO 😀
Hi RF Man, I love RF and you have some very interesting stuffs. I like your contents. Just subscribed. ECErcuit.
Thank you!
Superb...
nicely done
Would you upload more videos about RF? İ am learning it from you and they are excellent
That's super helpful! Thanks! I'd love the specific construction details of your little splitter- IE: what kind of cores for the transformers and what you used for the resistors. I've been wanting to make a splitter for a few receive-only applications that I want to run from the same antenna, and whipping up something like this would be ideal. I could probably wing it, but the more details the better. Thanks so much for the video.
I mention most of this in the video. I'm using material 43 for the cores, RG316 for the 50 ohm coax, and a 100 ohm (2xZo) 3 watt isolation resistor. It is wired as shown in the schematic. Compensation capacitors (22pF) may be needed depending on the construction. I hope this helps. Regards, RF Man
Excellent, what kind of the 100ohm resistor you put on it, and what is the wattage?
Typically a thick film metal oxide resistor is use. Wattage should be 50 to 100 watts depending on you application. Current only follow through the resistor when outputs are not balanced.
In your last example with the RF amplifier, does it cause any problems leaving the second output unterminated? Where is that other 1.5W being dissipated? In the 100 ohm resistor?
Yes, if you leave the output unterminated, the power will dissipate across the resistor. I wasn't concerned with only 1.5 watts. It is good practice to terminate both sides. Regards
Another great video!. I always enjoy and learn alot from your videos.
Quick question: The 2:1 auto transformer, the way I am looking at it might be wrong but I see it as a 4:3 turn transformer with an impedance ratio of 1.78. Is that correct? Thanks 785
Great vide explanation! Is there any device, or conjuntion of devices, that would allow me to have several receivers from a common antenna, but if any of the devices transmits, all the other devices should be isolated ? Don't know if I made the question clear, but happy to give more details in PM if needed. Thanks in advance
Amazing video, thank you very much! I guess that in the last experiment, the "other" 1,5w gets dissipated in the resistor?
With a 50 ohm load, the second port would also have 1.5 watts on the output.
T2 is not used to transform impedance because you have already two 50 ohms ports in parallel that give you 25 ohms! It's use for balancing between port.
Very interesting, I've made a similar hybrid combiner for two 100W AM Transmitter power modules, with success, using pairs of FB-43-1020 beads and ECW. So how would a 4 port configuration look like, that is, four 50 ohm input ports combined into a single 50r output port?
Email me and I will send you a schematic. My email address can be found on my website. rflinear-amplifiers.com
One thing you should have mentioned is the phase angle between the ports, 0 or 180 degrees. I will leave that with you to mention. Nice video. Good for those out there learning RF engineering. Also should have placed a 50 ohm load on the second port, as you measuring the power output of the splitter. (Balance)
73's
Can a combiner be used to combine the signals from two closely spaced antennae to present a stronger signal to the Low Noise Amplifier/RF Front-End?
I learned something. I did not know you could use coax for the winding. I thought that all windings needed to be next to each other, but with a coax the center windings run inside the shield windings.
Most high powered splitter combiners used with LDMOS amplifiers used coax. This is the primary application.
So is it possible to run two amplifiers together to make a combined output for example 2 x 1kw amplifier to one coax out
Trying to understand the effect of using coax , is it true that the inner conductor will see the magnetic field going thru the core? The shield -only shields- the inner conductor from electric field?
I'm not sure I fully understand your question. Let me answer it this way. If you have a ferrite core and wrap one turn of 50 ohm coax around it, the inner conductor and the shield will have the same inductance when each is measured with an inductance meter. The permeability of the ferrite material has the same effect on both the inner and outer conductors.
Very nice, but where is the input and the input ground? Further: Very good and interesting.
The grounds are shown on the schematic. The female SMA connectors are all grounded using the coax shield. Regards
Hi, do you do custom work? I am looking for a fully built RF amp focused on 470-490 mhz. 3-5 watts. 12-15v dc. Do you have anything like this? Thank you, V
Hi What cores do i need for 2 x 1.5 KW Combiner on 1.8 Mhz Mix 61 or mix 43?
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This is a super awesome video!! I will look for this topology when looking at amplifiers and other RF circuits.
I am curious about one thing. If you want the 2 outputs have the same phase shift and amplitude why would you use the center core and shield of coax for the 2 conductors instead of identical lengths of single conductor wires? I would think they would have different surface areas or resistances because they are so different.
You are making turns on a transformer so you want the EM to radiate and not using the shield as a fixed impedance to ground.
What is the difference between winding it with coax or just single conductor wire?
You can also use single conductors and achieve similar results.
Do you have a email that can ask you about some amplifier questions?
RF Man et. al. what are the main use cases for a combiner or a splitter? 73's
The splitter is used to take a single signal source and use it drive 2 RF boards and the combiner can take the output from 2 RF boards and combine the power output. Thanks for your question. Regards
@@rfmanchannel6915 Ah, ok. Thanks RF Man. Excellent video.
for the first Auto-Transformer, Turns Ratio is 1.33 which gives only 1.76, how about using 14 turns : 10 turns, which gives 1.96:1
My question would be this ,on your version would the staking of the two cores cause a fluxation issue and cause a outa ballance of impedence or saturation ...causing a issue ..
Promo sm 😅