Saturday, May 20, 2017

YouKits SK-1A QRP 40m transceiver review

YouKits is getting a good reputation for low cost amateur radio gear. Their antenna analyser is well regarded. When I saw a new mono-band 40m SSB / CW transceiver for US$189 including postage I couldn't resist. It's called an SK-1A.

It arrived very quickly and was easy to figure out even without reading the user manual.

While it comes with a Yaesu branded speaker / microphone, it's not wired to use the speaker in it so you must use headphones or an external speaker. Note that this transceiver does not have a built-in speaker which probably isn't a bad thing given the small size of the case.


I've had two contacts so far, one local and another VK2 to VK3. Both reported good audio from me and I found reception at my end pretty good. Disconnecting the antenna shows that the receiver is sensitive enough to hear band noise which is all you need on 40m.

The display is clear and the backlight is bright. The manual includes instructions for adjusting the display but it's not brightness or contrast, it lets you switch the backlight on, off, or auto.

Internally, construction seems good with lots of surface mount components used throughout. There's no circuit diagram in the manual, which is a pity, but you can see that the 6 crystal IF is on 4.9152Mhz and there are a few SA602A balanced mixers in there along with an LM386 audio amplifier.


The VFO board behind the front panel is compact and the software works well although I find the way pushes on the knob change between going up and down in step size a little weird. The soldering on the PIC microprocessor looks a little rough on my unit but all seems to work reliably.


The final is an IRF510 and I get about 4W peak output. I like the way they use shielded coils.


Main board soldering is good but clearly done by hand rather than machine.


Internally there's a socket for the 18650 Lithium battery pack which they supply with a charger but it looks like you'd need to open the case to charge the battery.

This radio is lower sideband only (along with CW), which is perfectly fine for voice contacts but I was rather hoping to use it for digital modes which normally need USB.

While a traditional SA602 based design, this radio works well enough and is more compact than even an FT-817. 40m is a good choice for a mono band QRP radio. There's no deafening thump during receive / transmit switching like I get on some other designs and audio output is more than enough for headphones but a little low for an external speaker.

Wednesday, May 10, 2017

Radio Australia's Shepparton broadcasting site for sale

For the ham who has everything... a lovely 500 acre vacant site at Shepparton, Victoria, Australia complete with short wave antennas (I assume).

More details here.

They say it's a significant "land banking" opportunity, whatever that is.

Close to a highly regarded school and just "moments" from the Shepparton Town centre.

But seriously, the site is up for sale while there is a pending bill before the senate calling for the restoring of shortwave radio.

There have been 40 submissions received (including one from your humble blogger). The inquiry is due to report on 9th August 2017.

Lovely cabinet work on site:


I'm advised that the property will be sold with buildings only, antennas and feed lines above ground will be removed.

The local Shepparton News is reporting that not everyone is happy with the shut down of the shortwave service.

Sunday, April 23, 2017

rtl-sdr direct sampling on linux

There's a nicely put together rtf-sdr receiver box available on Ebay from China for about AU$45 with the direct sampling modification for HF already done for you and separate inputs for HF and VHF+.

There are several sellers so shop around.

You can see it on the right here and the box above it. (Click to enlarge)

Internally, it's an RTL2832U.

On my recent weekend visit to Kevin, VK2KB, I helped to get it going under Windows using SDR# software and this prompted me to get mine going at home under Fedora linux.

One mistake I've made before is that some USB cables seem to come wired only for charging and don't wire up the other USB connections. I wasn't seeing the device in lsusb and when I tailed the log (which, incidentally, has changed under Fedora since I last looked, to be sudo journalctl -f), there was no chatter as the device was plugged in. Trying alternate cables fixed this.

It turns out that GQRX finds the device just fine. To switch on direct sampling from the Q input, you set it like this:


CubicSDR saw the device but couldn't receive until I blacklisted the built-in TV reception driver by creating a file /etc/modprobe.d/blacklist.conf and entering blacklist dab_usb_rtl28xxu in it. Then I rebooted.

After that, the CubicSDR device config looks like this:


And it receives 40m SSB like this:


(There's not much on at this time of day).

Google reader alternative - tt-rss review

I still miss Google Reader which went away in 2013. It was an efficient way to catch up on all the RSS/Atom news feeds I subscribe to in a web browser.

The key feature I need is that whatever I use remembers what I've read and can be accessed from multiple devices that stay in sync.

When Reader went away I subscribed to FeedWrangler which works well but lacks a decent web interface so must be accessed from a macOS or iOS app such as Reeder.

Recently I've installed Tiny Tiny RSS, also known as tt-rss on a Fedora linux computer in my home network. The installation guide is good but I ran into a few things that were not right on Fedora 25.

I chose to use mariaDB (mysql clone) as the database although they recommend Postgresql.

From memory, the issues I encountered were:

  • PHP couldn't connect to the database due to secure linux. 
  • httpd couldn't write to the tt-rss web directory for config and cache writing. Needed # setsebool -P httpd_unified on
  • The name of the mysql driver for php is different, I needed # dnf install php-mysqlnd
  • # dnf install php-pdo php-gd php-mbstring php-common php-apc
To get my feeds imported, I exported the OPML file from FeedWrangler and imported it into tt-rss by going to Actions, Preferences, Feeds tab and there's a long horizontal panel called OPML that's a button for choosing the file to import.

The user interface is nice and clean and I particularly like how it responds to up and down arrow keys to roll through the stories in the scrolling panel.

Updating feeds


The authors suggest leaving a process running to do the updates (it sleeps periodically) but I prefer a cron job as follows:

*/30 * * * * /usr/bin/php /var/www/html/tt-rss/update.php --feeds --quiet

Anyway, so far I like it a lot and my plan is to eventually move it to a virtual server in the cloud. It looks like you can aggregate all of your unread items into a new feed and presumably read that from an app while out - this could possibly replace the commercial service I'm using at the moment.

Friday, April 14, 2017

QRPver pocket sized transceiver review

The QRPver is a US$80 1W QRP transceiver that is perfect for running digital modes such as PSK31. It connects to a computer via analog audio cables and has internal VOX so there's no need for an interface box or serial rig control.

It's about the size of a pack of cards as you can see in the photo on the right. 

I'm using it with Fldigi running on Fedora with a generic USB audio dongle. I did need to use the Sound application to increase the audio level a bit to get the VOX to trigger when I transmitted.

Note that the audio sockets are stereo sockets with left and right tied together so you do need to use stereo leads or you'll short audio to ground.

I ordered my QRPver for 14.070 (there are a range of bands and frequencies to choose from). 20m PSK31 was very lively a few years ago but at the moment seems rather abandoned for some reason, perhaps everyone's running JT65?

First contact was pre-arranged with Stephen, VK2BLQ who is pretty near by. Today VK5WOW popped up being operated by Grant, VK5GR who made a few comments about the signal not being all that clean and also it drifted about 20-50Hz during a longer over.


The QRPver draws just 20mA on receive and 650mA or so on transmit so it would be great for portable digital operation. The receiver seems sensitive enough and while not a perfect signal on transmit - something that might be because I need to tweak the level a bit or possibly there's some RF getting in to the audio - I think it's a great gadget for the travelling ham.

Tuesday, April 11, 2017

Switching from Ubuntu to Fedora Linux

Ubuntu has been great for me over about the last ten years. Prior to that I was a RedHat/Fedora user but when I joined a company that was all Debian based I made the switch and learned the joy of apt.

Recently I've run in to some hitches with Ubuntu. It throws up crash handlers from time to time. The ham radio applications offered in the official archives are often very old and recently I found that gnuradio installed with apt runs but crashes in use. (Building from source fixed this).

The announcement that Ubuntu is abandoning the Unity desktop and switching to Gnome prompted me to give Fedora another go (it's already on Gnome).

Things are smoother since last time I looked. On macOS the installer is downloaded in the form of a "media writer" application that downloads the image you need and creates a bootable USB key - much nicer that the dd business I've been doing.

Gnome is very slick these days and on the three machines I've tried so far everything mostly worked out of the box. On an HP laptop it didn't include the Broadcom wireless driver but that was fairly easily fixed. While not much is installed by default, I quickly wanted the nano editor. Amazingly hackrf was built in.

I'm quickly up and running with fldigi, wsjt-x, gnuradio, gqrx, and all the normal unix goodness. The work done by Ubuntu has raised the standard of all desktop linux distributions (not to mention the whole cloud and virtualisation world) and I'll miss Ubuntu for sure.

Fedora notes for an Ubuntu user

Instead of apt (or apt-cache and apt-get) there's something called "dnf" that replaces "yum". For some reason I find it hard to remember "dnf" and sometimes have to type yum so it will remind me.

sudo dnf update
sudo dnf search xxx
sudo dnf install xxx

I've eventually figured out that DNF stands for "Dandified Yum" but that fact is missing from the man pages. Under the hood it's Linux and all the tricks I've learned are the same regardless of the distribution.

Friday, April 07, 2017

First transceiver with built-in FreeDV

Fantastic to see Chinese ham radio gear for HF increasingly appearing. This one "RS-918SSB HF SDR Transceiver" caught my eye because the operating modes listed are: "SSB(J3E),CW,AM(RX Only), FM, FREE-DV"

That's the first time I've seen a radio with built-in FreeDV.

From the site:

Main Functions

Spectrum Dynamic Waterfall Display

Multiple Working Modes: Receive Mode, Transmit Mode, TUNE Mode, VFO Mode, SPLIT Mode

DSP Digital Signal Processing Noise Reduction

Automatic Notch Filter

Humanized Interface Color Display

Receive Fine Tuning Function, Changeable MIC Gain Value

VCC Power Supply Voltage Indication Table

Transmit Signal Strength Display Table

Multifunctional Instrument: SWR Standing Wave Ratio Meter, AVD Audio Frequency Meter, ALC Signal Modulation Meter

Specifications

Frequency Range - RX:1.8-30MHz TX:All HAM HF BANDS

Operating Mode - SSB(J3E),CW,AM(RX Only), FM, FREE-DV

TX Power - 5W (Standard, DC 13.8V) , 15W (Full,DC 13.8V)

Receiving Sensitivity - 0.11~0.89μV(RFC 50-20)  

Minimum Frequency Step - 1Hz

Operating Voltage - DC9~15V

Antenna Impedance - 50Ω

Frequency Stability -  ±1.5PPM @ Power on 5 Minutes (Standard) ; ±0.5PPM if Optional TCXO Used

Product Dimension (W × H × D) - 215×74×62mm(Mounting Bracket Included)

Weight - 623g

No idea of price yet and it looks pretty clunky but great to see FreeDV built right in.  (If there are others please let me know).

Saturday, April 01, 2017

Built a 2m J Pole out of copper pipe

Just for fun I tried receiving WSPR on 6m. I'm using a half G5RV but at the end of a long run of RG58 so losses at 50MHz are likely to be significant. Quickly VK2HC was received and Peter emailed to say hello.

I mentioned my poor 6m setup and Peter urged me to try a copper J Pole design for 6m. Only when thinking about it at the hardware store did it dawn on my that the length of over 4m wasn't going to support itself and so I chickened out and decided to try the same but for 2m.

I purchased lengths of 15mm copper pipe, an L piece and a T piece along with a small gas blowtorch. The Ham Universe J pole calculator gave me the lengths. Unfortunately I mistakenly cut too short and had to extend later but that wasn't difficult - Lesson: always cut antennas a bit long at first.

Soldering the joints is done by heating with the blow torch until solder melts on contact and then I let that "wick" in to the joint. Seems to work very well. Hose clamps were used to attach the coax (some waterproofing is going to be needed).

Front of house antenna farm: 1090Mhz antenna, 6m slim jim (on a squid pole), 2m J Pole (left to right):



It tunes up pretty well and gives an SWR below 1.1.