Tag Archives: Rigol

Quick Impressions of the Rigol DSA815-TG

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Needing to upgrade my spectrum analysis capability, I recently sold my trusty boatanchor HP 8558B to help finance a portion of a new Rigol DSA815-TG spectrum analyzer. Last week I was able to order the 815, and today it finally showed up on my doorstep. I first came across the 815 last year, at the 2012 Dayton Hamvention. I believe that it had just been released at that time, and I don't recall hearing any buzz in the ham radio world about it. I was very intrigued by it, and vowed to look into it further. A bit later, videos of the 815 in operation started showing up on YouTube, which got me even more intrigued (there's lots of very good, detailed videos available via search). The final nail in the coffin was the product review in a recent issue of QST, which was quite favorable.

A quick overview of the banner specs include a 1.5 GHz bandwidth, standard preamp, DANL of -135 dBm, 100 Hz minimum RBW, and the -TG option includes a built-in 1.5 GHz tracking generator (an absolute must-buy). It comes in a compact, yet solid, portable enclosure; about the size of a larger portable oscilloscope. The LCD display is clear, ample, and well-backlit. The unit also has a nice variety of connectivity, including LAN, USB host, and USB device, as well as 10 MHz reference in and out.

I had a chance to briefly run it through some measurements this evening, which I'll share with you below.

This first image is a capture of a local FM broadcast station on 100.3 MHz. You can see the standard FM modulation, along with the very blocky digital HD radio subcarrier.

test

The next capture is a tracking generator sweep of a narrow CW filter that I had lying in my junkbox. It only has 3 crystals, which you can tell by the fairly shallow skirts. I was concerned that the 100 Hz minimum RBW might be too limiting for measuring narrow CW filters, but by all appearances it seems to do a good job in conjunction with the tracking generator. You can also see the very handy automatic 3 dB bandwidth marker measurement, which makes the process quick and simple.

cwfilt

Here's a sweep of a 6-crystal SSB filter that I also found in my junkbox. Again, you can see how useful the 815 can be with this type of measurement. It only takes a few moments to get this result once you get familiar with the basic functions of the 815.

ssbfilt

Finally, I paired the 815 with a homebrewed return-loss bridge so that I could make a wideband sweep of my main station ZS6BKW antenna. Here you can see return loss plot from 2 to 30 MHz. The resonances in the ham bands are quite obvious (some are indicated with markers). I never did any trimming on the antenna since I use it with an autotuner, but you can see that it came in pretty closely on the first try.

antenna

Only having used the 815 for a few hours, I'm already quite addicted to it. It's going to be a hugely useful addition to my stable of test equipment. I'm sure you'll see many measurements from the 815 in the years to come on this blog.

HNY

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Yes, a belated Happy New Year greetings! It's hard to believe that 2013 is already well under way. I figured it was about time to give you a quick update on what's going on in the shack right now.

First up is the discrete component grabber receiver for 14.141 MHz that I prototyped to be paired with the OpenBeaconMini project. The receiver itself consists of a roughly 2 kHz wide crystal filter on the front end, feeding into a single-balanced diode ring mixer, which drives an AF amp using 2N4401 and 2N4403 transistors. Because I'm not able to put up a proper outdoor antenna for the grabber right now, I decided to put the VE7BPO cascode active antenna on it instead. It seems to work well, but I don't know for sure because there are basically no signals on this part of the band. I intended to use my Raspberry Pi with the receiver as a grabber, but I had no luck getting either LOPORA or QRSSVD to work properly and reliably. It may just be asking too much of the poor beast. So I'm going to try to appropriate another PC in order to get the grabber receiver QRV so that on-air testing of OpenBeaconMini can begin in earnest.

Discrete component monitor RX for 14.141 MHz

Discrete component monitor RX for 14.141 MHz

Next, I wanted to give you a very brief overview of my most recent purchase for the lab: a Rigol DS1022U arbitrary waveform generator. As far as I can tell, this appears to be pretty much the same as the DS1022A model that is sold in the US. But being a typical ham, I wanted to save a few dollars, so I purchased it off of eBay from seller who says he is an authorized Rigol dealer.

Rigol DG1022U Arbitrary Waveform Generator

Rigol DG1022U Arbitrary Waveform Generator

The DG1022[U|A] has two channels that can output a sine wave up to 25 MHz in 1 mHz (as in millihertz) steps. It can also provide square, ramp, pulse, noise, and arbitrary waveforms at lesser frequencies. It can modulate the waveform in a variety of ways, including AM, FM, PM, PWM, and FSK. It can, of course, also do sweeps of various parameters. The output amplitude into 50 Ω ranges from 10 Vpp on Channel 1 or 3 Vpp on Channel 2 down to 2 mVpp on both channels (or -50 dBm). The shielding on this AWG seems to be excellent. Using my HP 355C/355D attenuator combo, I can get a signal down to about -140 dBm (disclaimer: not a scientific measurement, made using my ear as a detector and listening on my IC-718). The dual outputs makes it very useful for a variety of two-tone receiver measurements, one of the big reasons driving my purchase. The Channel 2 output also doubles as a 200 MHz frequency counter input. Paired with the USB connectivity of the device (it seems to enumerate as a usbtmc device), that will be extremely handy for measuring oscillator drift. The DG1022 can also link the two channels together and give them a specific phase difference, as you can see below. This will make it very handy as a I/Q LO when I want to experiment with phasing and SDR rigs.

I/Q Output from DG1022U

So far, I've been very pleased with my purchase. I don't feel like I've had it or used it long enough to give you a full review, but I thought that this preview would at least be a bit helpful for those thinking about using it. One of my goals for the new year is to do a much better job of characterizing everything that I build. Since I intend to start selling transceivers in the near future, it's doubly-important that I can make accurate measurements of my products so that I can properly state their specifications. To this end, I've decided to sell off a bunch of my unused or replaceable test equipment (please take a look at the for sale posting) in order to finance the new, calibrated test gear. Next up on my purchase list is a Rigol DSA815TG spectrum analyzer (just reviewed favorably in the February 2013 QST), but that's going to require the sale of everything on that page!

Finally, I've got the CC1 prototype PCBs on their way from Seeed Studio right now. It looks like they just cleared customs in the US, so hopefully they will be in my hands in the next few days. With any luck, I'll have the first one built by the weekend and will be well on the way to a new beta test. I'll put up a quick post to show off the PCBs, and when the first prototype unit is completed. Stay tuned!