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Author Topic: $150 SDR transceiver system?  (Read 13315 times)

W9SK

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$150 SDR transceiver system?
« on: March 13, 2016, 04:33:57 PM »

I spend a good deal of time working with middle & high school teens in ham radio (SCR, JOTA, electronics/robotics clubs, etc) who are interested in "moving up" to HF and General license.  But they face a huge obstacle: high cost of HF transceiver systems (radio + power supply + transmission line + antenna) that can do digital modes (PSK, WSPR, etc), which is what the new Gen Zers and Millennials are most interested in.  SO the question is:

Is it yet possible to assemble a SDR receiver, transmitter (or single transceiver), plus wire antenna, plus 50ft coax, plus power supply for $150 or less ?? (excluding a laptop/tablet, which all of them already have, of course) Assume that I'll provide design for a wire antenna, but cost of wire and any balun must be included in that total. What is the cheapest price point for a total system at the moment?

I'm fairly new to SDR and am researching, thus why I've come to this forum of more knowledgeable folks.  What say you?
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W9OY

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RE: $150 SDR transceiver system?
« Reply #1 on: March 13, 2016, 07:58:41 PM »

Depends on the quality you want.  About all you're going to get for $150 is a softrock which is a kit and while not hard to build it's not trivial for a 12 year old.  As soon as you start adding things like soldering irons, solder, multimeters, swr bridges, etc the cost explodes.  It's a SDR-1000 style of SDR radio which means it needs a sound card of adequate quality to work.  It's QRP and I would never direct a noob to buy a QRP radio as the first radio.  Way too frustrating for too little payoff IMHO.   

73  W9OY
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AE5X

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RE: $150 SDR transceiver system?
« Reply #2 on: March 14, 2016, 04:41:54 PM »

It's QRP and I would never direct a noob to buy a QRP radio as the first radio. Way too frustrating for too little payoff IMHO.  

Not for WSPR, PSK, JT65, etc, etc...
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W9OY

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RE: $150 SDR transceiver system?
« Reply #3 on: March 14, 2016, 08:43:36 PM »

The softrock runs 1 watt.  For those modes you would likely need a second sound card.  The whole thing would become very kludgy.  I've built a couple softrocks and the software for the softrock is not nearly as robust as SSDR or PSDR.  I'm not sure if you can run VAC with it, but I doubt it and VAC costs money.  Also you need an effective, efficient antenna.  Just because these modes are amenable to lower power does not mean they are forgiving.  Neither are they amenable to poorly set up gain and are easy to overdrive.  I got into ham radio at age 11, and just recalling my experience I would never have mastered setting up PSK or JT65 on this kind of rig.  I may have been able to get something like this going on an Anan 10E which is much more set up for such modes, and has a realistic amount of power.

73  W9OY
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W9SK

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RE: $150 SDR transceiver system?
« Reply #4 on: March 15, 2016, 11:27:33 AM »

Thanks for the quick replies, guys. 
Yes, I agree that the soldering assembly of a component kit for middle, and some high school, kids would be challenging, but at least in this case they have opportunity to be trained via a club setting on school premises or in the community on soldering, using inexpensive soldering stations & tools.  Of course, the ideal solution would not require soldering or cutting cases, but such would be a start for some kids (besides all the extra benefits of learning new hands-on skills).
I'm less worried about software installation and tweaking, as today's kids I work with are very used to installing apps, many have ventured into Linux distros even in middle school (and if you think setting up apps & gear with a Windows/Mac laptop is a chore, you have an eye-opener to experience with Linux systems).  Millenials and Gen Zers are the new digital generations who are not afraid to at least try and often figure stuff out on their own with Google search.  With that said, I spent my entire career in hi-tech, mostly in the computer hardware/software industry, and believe that that goal should always be to eventually make those solutions "grandma simple" if possible, as no one complains in the end AND it opens up this particular application to those older adults who just got into ham radio and are astonished at the high cost of off-the-shelf HF radios/antennas/etc (as we know, VHF/UHF FM has finally become dirt-cheap).
Yes, 1 watt is marginal for PSK31, esp WSPR, altho doable for the QRP fans.  5W is much more desirable, 15W is often too much and generates complaints.  At least the low power is working in our favor for a digital-mode-only solution.
I use a Signalink USB (built-in sound card) and have become spoiled from avoiding typical laptop sound card limitations, but that box is another $100 at best.  But the good news is that the laptop & tablet sound card chips have improved considerably and since these kids typically get a new laptop every 3-5 yrs, and tablet every 1-3 yrs, I see much of that limitation going away...as long as we can get the I-Q audio via stereo into the devices easily/cheaply. W9OY: what audio chip is in the computer(s) you've used SoftRock with?
Arduino & RasPi based transmitters are starting to appear, which I find interesting, and since USB ports are on all of them and even cheap Bluetooth appearing on some (with A2DP and SPP stacks) I'm hoping to find a solution there, even if it needs an external linear amp to bump power up to 5W.
So I just came across the Peaberry SDR v2 transceiver kit, and wondering about its performance (surface mount soldering, ugh!, that would for sure be beyond the capabilities of teens, tho).
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CS7AJS

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RE: $150 SDR transceiver system?
« Reply #5 on: March 15, 2016, 12:51:56 PM »

It's possible to use a RasbPi to transmit, without anything else but the rasbPi and a wire  ;D

Yes there will be harmonics all over the place and power is only a little bit more than a couple mW, but it could be a good base of evolution. Explain why and build BPF, try and get an amplifier out, etc. Simpler than going full into a Softrock, cheaper and with better progress.


http://www.rtl-sdr.com/transmitting-fm-am-ssb-sstv-and-fsq-with-just-a-raspberry-pi/
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K6JH

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RE: $150 SDR transceiver system?
« Reply #6 on: March 15, 2016, 07:02:03 PM »


So I just came across the Peaberry SDR v2 transceiver kit, and wondering about its performance (surface mount soldering, ugh!, that would for sure be beyond the capabilities of teens, tho).


Peaberry is now sold as "Omnia" and is available with the surface mount stuff already soldered ($135), and with a pre-fabbed coil kit ($33). http://www.omnia-sdr.com/index.php?main_page=index&cPath=65
 
The advantage of Peaberry/Omnia is it has the sound card ADC built in, vs. the Softrock RX-TX which needs a good stereo soundcard to run it (I had to use a USB Soundblaster to run my Softrock Ensemble RX with a laptop). You're still stuck at the 1W level with either unless you add an outboard amp.

A forum is available for Omnia support. https://groups.yahoo.com/neo/groups/omniasdr/info

Disclaimer: I have no personal experience with Peaberry/Omnia, so YMMV.

BTW, I actually don't think surface mount soldering is that tough - you don't have to figure out how to keep parts in place while you flip it over to solder from the bottom. Us old pharts do need a good magnifier though. Of course I've been soldering for 50 years.  ;)
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73
Jim K6JH

K6JH

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RE: $150 SDR transceiver system?
« Reply #7 on: March 17, 2016, 01:50:05 PM »

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73
Jim K6JH

W9OY

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RE: $150 SDR transceiver system?
« Reply #8 on: March 17, 2016, 06:48:43 PM »

W9SK   I ventured into the softrock scene maybe 7-8 yrs ago, so  the computers/OS was much different than today.  Maybe an old thinkpad and XP.   I was using a high end firewire based card from my recording stuff which worked pretty well.  The biggest problem with surface mount is not the soldering except you need a very good temp controlled 1/64" 800 deg iron (not cheap)  The real issue is the parts are very high in kinetic energy and are constantly trying to escape into a different dimension.

The Omnia looks interesting I think better than a softrock.  You could drive some 50 ohm resistors and make PSK/rtty/CW QSO's between students.  This would give the experience and would weed out the merely interested from the truly on-fire who might them acquire a more advanced radio, plus everyone would have an excellent SW radio to  tune around and listen so this would get you pretty close to your $150 criteria.

73  W9OY
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KZ1X

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RE: $150 SDR transceiver system?
« Reply #9 on: March 22, 2016, 06:19:26 PM »

The Omnia (I have built three of the predecessor Peaberry radios, substantially identical) has already been pointed out.
A watt is plenty for most digital modes, if the antenna used isn't an elevated dummy load.

However, assembly is not recommended for an inexperienced person.

Another way to go is the monoband, ready-built '2015' version of the Small Wonder Labs PSK series. 
These are now sold by a Ukraine ham.
 
http://transverters-store.com/psk.htm

Pretty inexpensive.  I'd just get the 20 meter 14.07 MHz model for the students. 
There's always tons of activity around that frequency and a magnetic loop is easy to make and just 3 feet across.
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