3 dB HYBRID COUPLER/ISOLATOR FOR ANTENNA SPLITTING 100 KHz -10 MHz

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glovisol
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Location: Piedmont, Italy

Re: 3 dB HYBRID COUPLER/ISOLATOR FOR ANTENNA SPLITTING 100 KHz -10 MHz

Post by glovisol » Sun Apr 21, 2019 3:32 pm

NETWORK ANALYSER MEASUREMENTS

Shown below is what one receiver sees into the 50 Ohm splitter with the other receiver in operation and the antenna port connected to a long wire antenna through a 50 to 560 Ohm transformer in the frequency range 3 to 10 MHz. As can be seen, termination quality is excellent, with a return loss in the range of 10 dB or better in the frequency range examined.
Attachments
Antenna looking into 50 Ohm splitter 1.jpg
Antenna looking into 50 Ohm splitter 1.jpg (97.41 KiB) Viewed 1800 times
Antenna looking into 50 Ohm splitter 2.jpg
Antenna looking into 50 Ohm splitter 2.jpg (109.46 KiB) Viewed 1800 times
Receiver looking into 50 Ohm splitter 3.jpg
Receiver looking into 50 Ohm splitter 3.jpg (95.81 KiB) Viewed 1800 times

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ON5HB
Posts: 140
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Re: 3 dB HYBRID COUPLER/ISOLATOR FOR ANTENNA SPLITTING 100 KHz -10 MHz

Post by ON5HB » Mon Apr 22, 2019 4:25 pm

sdrom33 wrote:
ON5HB wrote:
What do you mean wrong info and specs?
It's not a transmitter but a receiver, as such impedance isn't crucial to good workings.
Exactly what I wrote. The official published specifications by Sdrplay say: 50 Ohm input impedance. If you write in so many words it is not so, you are being unfair to Sdrplay and misleading other forum members. It is not a question of "transmitter" or "receiver".
If you are sure that the Rsp1a input impedance is not 50 Ohm, open a ticket. Anyway if you look at the previous post you can see the rsp1a input impedance is 50 Ohm spot on.
You are measuring SWR, as such it may be 50 Ohm.
I do not care about SWR nor do I ever conclude anything from antenna-analyzers or SWR meters.
Antenna-analyzers have been proven to be wrong so many times, it's not funny any-more.

Example, you can perfectly connect a 50 Ohm dummyload with a T and a bit of wire, it will be 1:1 perfectly and even transmit a signal.
There won't be any losses but still it's not an antenna nor does it work.

I have a G5RV connected and splitted 3 ways with T-connectors, signals are very strong and I'm very sure it's nowhere near 50 Ohm.
When I use a 50 Ohm splitter the signals go down a lot. I noticed this and stated as such.
I fail to see where it's unfair or misleading. The RSP1A's work splendid far better then anything I have used before, even better as the Icom7300.

Funny is, I installed and MFJ SDR-switch the other day, the RSP1A's have the same signal as before, but the Icom7300 dropped by 10~20db in reception.
Why did the Icom drop and the RSP1A's didn't?

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Mike2459
Posts: 318
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Re: 3 dB HYBRID COUPLER/ISOLATOR FOR ANTENNA SPLITTING 100 KHz -10 MHz

Post by Mike2459 » Mon Apr 22, 2019 6:32 pm

Nowhere in the RSP-1A spec sheet is it stated that the RSP-1A has an input impedance of 50Ω.
It does say this under the heading: Connectivity: "Single 50Ω RF connector (SMA)"

My non-professional knowledge of this topic suggests that circuit impedance is determined primarily by the source (the antenna in this case) and not the load.

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sdrom33
Posts: 128
Joined: Sun Dec 09, 2018 4:38 pm

Re: 3 dB HYBRID COUPLER/ISOLATOR FOR ANTENNA SPLITTING 100 KHz -10 MHz

Post by sdrom33 » Mon Apr 22, 2019 6:43 pm

Bas,
First I asked you to state what splitter you were using, so you could find in the forum somebody that could help you sort out your problem, you did not even reply on the point, sure you know it all already & you do not need any advice.

My dear Sir, electronics is science, radio communications is science, what matters is not what your opinion is, or mine, but what science, measurement and laws of electronics tell us. You are entitled to your beliefs and opinions, but I think I can contradict you when you negate, in our Forum, with your obscure notions, the obvious truth represented by published specifications.

Perhaps I should remind you that you are sure, as you wrote in this thread a few days ago, that rsp receivers have no local oscillators and no mixers.... :lol: now we should believe your theories about vswr?

Perhaps it is my turn to tell you to take it easy, life is great, go and walk the dog.

Sdrom33

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sdrom33
Posts: 128
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Re: 3 dB HYBRID COUPLER/ISOLATOR FOR ANTENNA SPLITTING 100 KHz -10 MHz

Post by sdrom33 » Mon Apr 22, 2019 7:02 pm

Hi Mike,
in the same sentence you say that in the spec SRDplay states for "Connectivity" e.g. "input" is: "single 50 Ohm RF connector" and then you say that 50 Ohm has not been specified? Next time you are going to tell us about flying horses?

In the same vein then Sdr play does not specify the receiver has a 2 Mhz lowpass filter built in, they do not say it, they only state: "front end filtering", nowhere they state there is a filter inside....
This is the more amazing when you have instrumental proof in this same thread. :lol:

Cheers,
Sdrom33

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Mike2459
Posts: 318
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Re: 3 dB HYBRID COUPLER/ISOLATOR FOR ANTENNA SPLITTING 100 KHz -10 MHz

Post by Mike2459 » Mon Apr 22, 2019 7:17 pm

I have a 50Ω BNC coax connector on about 75 feet of RG6 75Ω coax. Is that RG-6 now 50Ω coax?

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sdrom33
Posts: 128
Joined: Sun Dec 09, 2018 4:38 pm

Re: 3 dB HYBRID COUPLER/ISOLATOR FOR ANTENNA SPLITTING 100 KHz -10 MHz

Post by sdrom33 » Mon Apr 22, 2019 7:29 pm

The right reply is that nobody in his senses would use a 50 Ohm connector on a 75 Ohm coax....come Mike, stop this nonsense and have a peaceful Easter, :D

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sdrom33
Posts: 128
Joined: Sun Dec 09, 2018 4:38 pm

Re: 3 dB HYBRID COUPLER/ISOLATOR FOR ANTENNA SPLITTING 100 KHz -10 MHz

Post by sdrom33 » Mon Apr 22, 2019 7:46 pm

ON5HB wrote:

Funny is, I installed and MFJ SDR-switch the other day, the RSP1A's have the same signal as before, but the Icom7300 dropped by 10~20db in reception.
Why did the Icom drop and the RSP1A's didn't?
Bas, it is the rsp1a magic....It receives better because it has no mixers... : :oops:

In fact where Sdrplay specified they use mixers? They only use oscillators "to make them tick..."...ask Mike.

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Mike2459
Posts: 318
Joined: Mon Jul 24, 2017 8:24 pm

Re: 3 dB HYBRID COUPLER/ISOLATOR FOR ANTENNA SPLITTING 100 KHz -10 MHz

Post by Mike2459 » Mon Apr 22, 2019 7:50 pm

Ok, While your devouring that chocolate bunny consider this:

https://hackaday.com/2015/07/29/say-it- ... impedance/

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sdrom33
Posts: 128
Joined: Sun Dec 09, 2018 4:38 pm

Re: 3 dB HYBRID COUPLER/ISOLATOR FOR ANTENNA SPLITTING 100 KHz -10 MHz

Post by sdrom33 » Mon Apr 22, 2019 7:53 pm

Think with your own head, do not believe in false prophets, trust what you measure and see...I have gone to walk the dog...take it easy.

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