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SDR has arrived and what a strange new thing it is.




 
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Author Topic: SDR has arrived and what a strange new thing it is.  (Read 725 times)
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Patrick J. / KD5OEI
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« on: August 25, 2017, 10:13:40 PM »

The bullet has been bitten in the name of science, and the SDRplay I came home with me. The software was simple to install, the documentation leaving a lot to be desired for someone who has not used an SDR before, but it works.

When used as intended it works pretty well and I see there are several software packages for it and I downloaded all of them. I installed SDRuno as recommended on the radio's packaging and have not tried the others yet but I will have to.

Sometimes after fiddling too much with the parameters (almost everything can be fiddled with), clicking on a memory/memorized setting sometimes does not restore -everything- and restarting the software recovers the normal operation.

Some very unusual noises have been produced and at first I thought it was either an evil spirit from the other world or the incoherent mumbled growlings of a badly hung-over heavy metal vocalist hiding behind my speaker, but it turned out to be the product of selecting several settings in a certain order apparently not foreseen by the software team. I consider this a feature.

Radio Armenia was heard on a 10 FT piece of wire hanging down the wall. The noise of the power lines, alarm system, and whatever vile piece of equipment is responsible for the 24MHz blowtorch, was gotten rid of, mostly, by the SDRuno noise filter. It may make a nice bedside SWL setup if paired with a notebook and one of those aftermarket 'knobs on a box' for convenience and a good RX loop like the RF-PRO-1B. It does lack the beauty and the mysterious, faraway, SWL-ish tessitura that is inherent in an SX-28 Super Skyrider with bass reflex cabinet, but the SDRplay is more versatile and definitely drifts less.

The reason for buying the receiver is to look for harmonics at the output of my transmitters and amplifiers. The SDRuno software only allows a 10MHz section of spectrum to be observed at once but I hope another package will provide, for example, a 1-100MHz sweep for the stated purpose.

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Radio Candelstein - Flagship Station of the NRK Radio Network.
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« Reply #1 on: August 25, 2017, 11:03:59 PM »

It's awesome.  I use mine as the station receiver for all my equipment. 

I'm using the SDRplay II, and I find that even it is prone to broadcast band interference.  I've put both an AM and FM broadcast band filter on it.  There's lots of transmitter sites around me. 

I also put a 3db attenuator for good measure.  The SDRplay documentation warns against using it along with a transmitter on the same coax.  When I'm transmitting, the attenuator provides at least some amount of protection.  I've used it along with a 1500+ watt transmitter without incident.  (Well, aside from burning down the backyard, but that was another story).

Jon
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Patrick J. / KD5OEI
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« Reply #2 on: August 27, 2017, 12:01:04 PM »

"The same piece of coax", was mentioned in the instructions.  - so this is not a warning similar to 'don't connect a transmitter to the input of the receiver'?

Does it mean not to use it with the usual T/R switching setup?

Two setups here - -
1. relay
2. electronic switch
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« Reply #3 on: August 27, 2017, 12:29:49 PM »

Maybe they left it purposely vague to cover any situation. That way, if somebody does something stupid they can say, "We told you!"

I'm using a regular commercial coaxial antenna relay. Any transmitted RF is sequenced after the antenna relay activates to provide additional protection.

On the other hand, I really would like to see someone connect the SDRplay to the output of a large transmitter. It might actually light up like an incandescent bulb does.

Jon
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« Reply #4 on: August 28, 2017, 08:46:01 AM »

There is an SDRplay group on Facebook and an excellent collection of videos on YouTube. I highly suggest you watch them. That receiver has so many somewhat hidden features. It is far better than many believe it to be.

https://www.facebook.com/groups/sdrplay/

https://www.youtube.com/playlist?list=PLOlniSsm2f1PX3BHHZ4jS8q-qkgUiHE0V
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« Reply #5 on: August 29, 2017, 11:29:32 AM »

Several SDR dongle users have wired the receive side of T/R relays in series, that is two sets of switches in cascade, first set of contacts opens the coax and second set of contacts opens it again and grounds the receiver input.

In cases with both QS1R and Anan type products, a single T/R relay set to open Tx and simultaneously ground the receiver is usually adequate since the LTC 2208 ADC has high overload spec along with variable attenuators and low pass filters restricting input to HF through 6 meters.
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RICK  *W3RSW*
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« Reply #6 on: August 29, 2017, 12:16:39 PM »

Ah, that's an awesome idea! I have a smaller BNC type coaxial relay to use with a BNC type 50 ohm termination. Then I can get that 3db attenuator out of line.

Jon
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« Reply #7 on: August 30, 2017, 07:24:11 PM »

Perfect suggestion.

I've done the "short the RX input" thing on T/R switches, works good, so that is what may be done here.

I use a RF-PRO-1B loop for receive and some SWL. It can definitely make a big signal at its output and comes with an electronic control that removed B+ from the loop's amplifier on TX.  When the loop is close to a very big signal, it will sort of self-power or in some way pass a good sized signal. It might be wise to do the "short the RX input" thing after it as well.

Back to the intention for it, a sampling network of some sort would be good for checking TX harmonics. I found that there is a difference sampling them from the TX coaxial output through an attenuator and sampling them from "the air" in the shack. Due to imperfect grounds, other weirdness? who knows.. trash will appear in the shack aether that is not in the TX output, (and is not on either side of the ladder line).

For understandable reasons I don't want to connect the hallowed H/P 141S spectrum analyzer to the transmitter unless I can really be sure of the safe signal level.
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Radio Candelstein - Flagship Station of the NRK Radio Network.
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« Reply #8 on: September 04, 2017, 11:18:33 AM »

I really like the SDRPlay and the SDRuno software. It will do a great job of checking the harmonics of your amps and transmitters. I often use the I/Q recording feature with the SDRplay running on the second station computer and queued up to record one of my rigs as it transmits into the station dummy load. You can easily check for splatter, harmonics, and audio quality when the IQ recording is played back. Another slick thing to do instead of making large I/Q recordings is to use the free OBS Studio screen capture suite to create HD quality mp4 videos of the SDRuno spectrum display as you are monitoring your transmitted signal.

https://obsproject.com/

It's pretty hard to beat the SDRplay for general SWL, VHF, and UHF receiving as well as its ability to function as an inexpensive 10 MHz wide spectrum analyzer. You probably already found it but if not, the free SDRuno Cookbook by NN4F - Paul Jones is an excellent PDF document that helped me to get a grasp of all the things that the SDRplay can do with the SDRuno interface. The slickest thing I learned in there was how to save a variety of different SDRuno layouts. Makes it easy to switch between compact displays and full displays of all the control panels. There are also similar documents for using the SDRplay with Simon Brown's SDR Console software.

http://www.nn4f.com/index.php/14-sdr-console-v3-sdrplay-guide.html

I think you grabbed the best bang for your buck with the SDRplay!

73,

Rob W1AEX
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One thing I'm certain of is that there is too much certainty in the world.
Steve - K4HX
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« Reply #9 on: September 04, 2017, 01:47:45 PM »

I've used mine with SDRuno, SDR Console and HDSDR. Each of them has some nice functions and features but none does everything I need/want.
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