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Introduction

The WU2O station is operated from a second floor studio and office, far away from the actual radio equipment, which is located in the basement. The only link between the studio and the radio equipment is a hardwired Gigabit Ethernet LAN connection. This is possible because the most of the equipment used can be remote controlled via Ethernet, either directly or via an RS-232 device server (see my radio station page). Having a separate studio is quite pleasant and comfortable. It stays neat and clean, the only noise is from the very quiet PC fans, and speakers can be used without disturbing the rest of the household.

Be sure to click on the photos above and below for a closer look.

Computing Hardware

While it does not require a crypto-smashing PC to enjoy software defined radio (SDR), having a fast computer with lots of power makes the entire experience a lot more fun. I built my own PC from scratch to achieve my goals of fast, cheap (< $1,500) and quiet. To that end, it is an i7-7700k, de-lidded and overclocked to 5GHz (not kidding, 5GHZ!) on an EVGA motherboard. The sound isolated case and water cooling are from Corsair. Both CPU and GPU are watercooled to keep fan speeds low. With some judicious shopping on eBay and elsewhere, I was able to also provision 16GB of 3200MHz RAM and a Samsung M.2 250GB solid-state hard drive and still keep the total cost under $1,500. The operating system is, of course, Windows 10 Pro, given the prediliction of amateur radio software developers for the Windows operating system.

Display Hardware

Again, having acres of screen real estate is not a must have for using an SDR, but once you go to two monitors you'll never go back to one. And once you go to a 4K monitor you'll never go back to something smaller. I got an incredible deal on Craigslist. A local software engineer was retiring and selling three, matched Dell P2815Q 4K monitors for a ridiculous price: $150 for all three! Who could pass that up? An EVGA-1070 video card does the honors, with three dedicated Displayport outputs. These are not super-fast gaming monitors and only run at 30Hz, but that's plenty fast for SDR software. I think you will agree that it adds some "wow factor" to the station, and now I have more screen area than I know what to do with!

Software

Software is, of course, the heart and soul of any software defined radio. And, given that the radio used in the station is a "thick client" architecture radio whereby all processing on the speaker and microphone side of the first and only IF is performed by a software application on the PC, of terrific importance. Adding to this is the necessity for software control of all station equipment and functions given the remote location of the station from the studio.

My normal operating environment on my primary 4K monitor appears in the photo below (click to enlarge it). Clockwise from the upper left:



Other important software used but not shown includes: There are a number of other software applications used on the station that are too numerous to mention, including TQSL, WSJT-X, JS8Call, Winlink, etc. These applications, and DXLab, are relegated to the two 4K displays on either side of my primary monitor.

Mouse & Keyboard

Obviously it is very important to have a high quality, RFI resistant, mouse and keyboard with which to operate your SDR software. Get something with well shielded cables, or, better yet, nearly any 2.4GHz wireless unit will be practically invulnerable to amateur radio RFI.

My mouse of choice is a Logitech M705 wireless mouse with "Hyperscroll". It uses plain old AA batteries that last a year and don't require fussing with recharging. And the Hyperscroll feature provides a really fantastic, very knob-like experience when tuning the radio, not to mention makes a huge difference in scrolling through web pages or regular documents.

As much as I like Logitech keyboards, I could not pass up having a fancy, mechanical keyboard with programmable lighting, in this case a Corsair K70 RGB. I love the mechanical keys. I recommend the Cherry MX Brown keys, but they have other versions to match your taste. More importantly, the programmable backlighting allows me to highlight the various keyboard shortcut keys that operating the SDR software. Plus it just looks cool.

Microphones

I prefer microphones with a ruler flat frequency response. The old school method was to do your frequency equalization in the microphone. With all due respect to Bob Heil, this approach is outmoded now that we have radios with sophisticated, multiband, parametric equalizers built in. For this reason I prefer microphones with as close to a flat frequency response as I can get and to do the equalization in the radio. This way I can sound how I want to sound and not how Heil wants me to sound.

The station reference microphone is a Behringer B1 large diameter condenser. It's a fabulous mic with a very flat response typically available for less than $100. Highly recommended!

The microphone I use the most is my AKG WMS-420 headworn wireless microphone. It is also a professional condenser microphone with a nearly flat response. With this mic, using VOX I can roam around the studio and get things done without being tied to a particular operating position. With some judicious equalization, you can barely tell the difference between it and the B1.

Audio Interface

This is, beyond any doubt, the most critical part of the studio setup, because with a remote studio setup like mine all audio must be sourced and sinked at the PC. The SDR software will happily entertain most any interface, but to support low latency it is important to have an interface that can use ASIO sound drivers, and to have an audio interface that can provide full 48V bias voltage to the professional condenser microphones. And, for even lower latency, to have an interface that uses USB 3.0, which of course is much faster than USB 2.0. For those reasons I have chosen the Presonus Studio 192 Mobile interface. Not only does this interface accept the audio from my two microphones, but it also acts as the output for all PC audio, including that from the SDR software. All connections are made using XLR type, fully balanced and shielded audio cables, which pretty much eliminates any chance of RFI. And it includes a high power, professional headphone amplifier output.

Speakers and Headphones

This might sound crazy (pardon the pun), but after the amplifier the best thing I ever did for the station was to buy these fabulous speakers, a pair of JBL LSR305 powered studio monitors.

Let me tell you, communications experts they may be, but hams just don't seem to understand sound reproduction. For instance, the $200 Elecraft SP3 speaker is a single, crappy cone speaker in a metal box with some insulation inside. For Two. Hundred. Dollars. Seriously? That's just dopey. On eBay you can find, brand new, pairs of LSR305 powered studio monitors for less money. These things, and other, similar, studio monitors, will just blow any so-called ham radio speakers away. Buy them, or something like them. They will change your life!

For headphones I can highly recommend the Presonus HD7. Lightweight, comfortable, inexpensive, and far and away better than expensive stuff from the likes of Heil. Don't believe me? Order a pair from Amazon and return them if you don't agree! If you have an expensive and powerful headphone amp like I do, consider a pair of beyerdynamic DT770 Pro's, in the correct impedance to match your amplifier, of course. Sadly, I rarely use them, because those JBL studio monitors are so fantastic!

Knobs and Switches

For meat and potatoes PTT, I use a nice foot-switch I found at my local surplus electronics place. Not noteworthy by itself, but what a lot of people don't know is that most SDR software applications will happily interface to a physical switch by means of a serial port connection. No need to use the spacebar, or the mouse. Use a real switch. Research such a connection for your SDR software of choice. It's generally a trivial connection involving the DSR or CTS pins. You will be much happier.

The other big complaint about PC-based SDRs is that they have no physical knobs or switches. Personally I don't care too much about that. I am quite comfortable and very fast operating the radio with a mouse. However, it can be convenient to have a few knobs and switches from time to time. As it happens, the software used here, Thetis, supports a wide variety of MIDI controllers as control surfaces. It allows you to program any knob or button for nearly any available CAT command. I use a Hercules DJControl Compact MIDI controller. It is very small, fits under my monitors when I'm not using it, and has just enough knobs and switches for me. Make sure you have a good labelmaker to label those controls, though!

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