SDR Radio Fun ($149 USB tuner with range from 100khz to 2Ghz!)

[Cliff Matthews]

Saw a fun video today from Budd Churchward's YT channel called "Strangest Thing On SDR Radio". While I'm not a HAM, I found it amazing (In Canada almost illegal?) all that a pocket-able device can hear..

[TheBay]

I've got an SDRplay, amazing bit of kit! Anyone interested in any form of radio I urge you to get one! 

[Cliff Matthews]

I've got an SDRplay, amazing bit of kit! Anyone interested in any form of radio I urge you to get one! 

I was wondering about an antenna for it, does it have to be long? My back-yard's only 25ft deep...
Would you have any tear-down photo's or pcb shots?

[Nerull]

I've got an SDRplay, amazing bit of kit! Anyone interested in any form of radio I urge you to get one! 

I was wondering about an antenna for it, does it have to be long? My back-yard's only 25ft deep...
Would you have any tear-down photo's or pcb shots?

Your antenna is going to be frequency-band dependent. There is no magic antenna that will receive everything from 10m band (28MHz) to ADS-B (1.09GHz), at least not well. You need something tuned to the frequency you want to listen to. Antennas are generally some fraction of a wavelength long, so the higher the frequency, the smaller your antenna will be.

A 5/8 wave antenna for 28MHz (10m wavelength) is going to be 6.25m long. A 5/8 wave antenna for 144MHz (2m wavelength) will be 1.25m, etc.

My mobile VHF/UHF antenna on my truck is a little Comet SSB-1, which is a close-enough-to 1/4 wave antenna on 144MHz and a close-enough-to 1/2 wave antenna on 440MHz (70cm) and is only about 40cm tall including the base. Its not got the gain of a larger antenna but it works well enough for my needs.

This all gets a little more complex when you start looking at other antenna types. My antennas are all monopole and require a ground plane. There are dipoles, loops, helical, yagis, bow ties...

[Nerull]

There are also telescoping antennas which allow you to change the length to suit different bands. They're almost certainly not going to be as good as a band-specific antenna but they're far more flexible.

https://greatscottgadgets.com/ant500/

[vk3yedotcom]

I was wondering about an antenna for it, does it have to be long? My back-yard's only 25ft deep...

The old rule for low frequencies was 'the longer and higher the better' but for the HF range a 25ft wire will pick up plenty of signals.

Two things:

1. The antenna doesn't have to be a straight wire.  Eg it can run across and droop down at the end.  Doing that could give 33ft, which is 1/4 wavelength on 7 MHz. 
Just keep it as far as possible from possible interference sources.

2. Modern receivers should be sensitive enough but if you want a bit more then an antenna coupler between the receiver and antenna may boost the signal through
optimum impedence matching.  Two transistor radio variable capacitors and some wire wound on a toilet roll are suitable for a receiving only / low power transmit antenna coupler.

[retrolefty]

Another old rule is that if your antenna didn't fall down last winter then it's too small. 

[TheBay]

Totally depends what frequencies you want to receive, it's extremely wide range and there are quite a few different types of antennas for those ranges.

I have a Inverted L with radials fed in to a SGC 237 Smart Tuner, which covers HF 160m - 6m and a Diamond X-50 Co-linear that does 2m - 70cms, but will Rx a bit more than that.

As for a teardown, there isn't much inside it, I'll post a picture of it in the early style case below, I have the new style case and it's identical inside.

One area this beats quite a few SDR devices is the fact that it uses NO Upconverting at all, most have to upconvert HF to the range of the chipset, this will do 100k-2Ghz natively!
Also it has a front end filters and great bandwith.

I mainly use mine as a Bandscope/Panadapter via the RX out on my FTdx3000 so I can view a whole band at a time.

I've got an SDRplay, amazing bit of kit! Anyone interested in any form of radio I urge you to get one! 

I was wondering about an antenna for it, does it have to be long? My back-yard's only 25ft deep...
Would you have any tear-down photo's or pcb shots?

[Lightages]

Probably the best overall antenna one can use for these wide range SDR radios is a discone. A big one can cover 25MHz to 1.3GHz, all on one antenna.

[Cliff Matthews]

Probably the best overall antenna one can use for these wide range SDR radios is a discone. A big one can cover 25MHz to 1.3GHz, all on one antenna.

I have no problem with $100 price, but with something so strange in my yard, I'd be sure to get visits from "the nanny state"..  So with 4' of height in my attic, would a smaller version be poorly affected?

[retrolefty]

Probably the best overall antenna one can use for these wide range SDR radios is a discone. A big one can cover 25MHz to 1.3GHz, all on one antenna.

I have no problem with $100 price, but with something so strange in my yard, I'd be sure to get visits from "the nanny state"..  So with 4' of height in my attic, would a smaller version be poorly affected?

 Frequencies above around 100MHz are mostly line of sight, so having the antenna mounted as high as possible is desired. I have a small FM broadcast yagi mounted in my attic with a rotator. Works OK but I'm sure it would be better mounted higher outside. Also your roof material (flashing, etc) could have some effect. Main problem with a Discone is it's non-directional so no way to steer away from strong undesired signals in search for a desired one.

[Lightages]

Have a look here, lots of antenna designs to build. Look for the discone icon and download the freeware. They aren't hard to build. The bigger the more costly and difficult, but a small one can be built in a day.
http://www.ve3sqb.com/

There is nothing to stop you from building whatever you want and installing it in Canada, except if you signed some agreement for your condo/commons/neighborhood, or their are stupid appearance bylaws in your town.

[TheBay]

Just run a beverage antenna outside to get you going, as much wire as you can and just hide it over fences and stuff, that will get you on the LF-HF stuff and you can make something small for the VHF+ ranges.

Probably the best overall antenna one can use for these wide range SDR radios is a discone. A big one can cover 25MHz to 1.3GHz, all on one antenna.

I have no problem with $100 price, but with something so strange in my yard, I'd be sure to get visits from "the nanny state"..  So with 4' of height in my attic, would a smaller version be poorly affected?

[Cliff Matthews]

This is a follow-up where he shows what can be done with an indoor "slinky" antenna - Cheers!

[cdev]

Around a year and a half ago I bought a kit that does 100khz to around 1750 MHz for $28, built the part of it that needed to be built, and apart from some cosmetic issues (my fault because I don't have a nice drill to do it right, so I still have not finished the front panel.) its done and it works. Its still a bit delicate until the front goes on. Still, it gets a lot of use.  It works well. Even spectacularly, considering the size and it's price.

Its based on a rtlsdr inside and it direct samples. It's the size of a large box of matches.


As far as an antenna, use a length of wire outside with a 9:1 unun, at the antenna. A unun will reduce noise and decouple the antenna from your indoor (usually noisy) AC power.

[FLIP]

might be a better option than well the HackRF which i was thinking of upgrading too, mainly because of the fact it can get upto 6Ghz.   having said that how would this SDR device compare to one of the many wide band Icom IC scanners?

[Cliff Matthews]

might be a better option than well the HackRF which i was thinking of upgrading too, mainly because of the fact it can get upto 6Ghz.   having said that how would this SDR device compare to one of the many wide band Icom IC scanners?

KK6FU compared a brand new IC7600 with SDRplay: