Digital Ham Shack

I’m not sure of the percentage, but I suspect that most, if not almost all, ham radio stations of 2018 include a computer, usually connected to their transceiver. A computer is mainly used for:

Running logging, mapping, propagation, contenting, design, programming, and other sorts of software that may or may not require direct connection to the radio.
Running rig control software – to monitor frequency, change modes, control transmission, and perhaps rotor or antenna control.
Running SDR software.
Running digital mode software, which included encoding and decoding via the audio interface, and usually includes some basic rig control.

This short article will discuss the computer / transceiver interface, including rig control and the audio interface.

computer-rig-interface

CAT Rig Control

For modern ham transceivers (1980s and later) with microprocessor control (frequency, modes, etc.), a protocol called CAT (for Computer Aided Tuning or Computer Aided Transceiver – it is unclear which is the real term) allows a computer to remotely control various aspects of a transceiver. CAT can control frequency, transmit, modes, and other controls found on typical transceivers.

Until fairly recently (perhaps 2010), the CAT connection to the computer was via an RS-232 serial interface cable. Sometimes a simple RS-232 cable will work, but not all radios have used standard RS-232 voltages, and level conversion hardware is often required.

There are a number of commercially available boxes that can connect computers to radios, often including the audio connection.

More recently it has become more and more difficult to find a Windows based PC that has an RS-232 port. There are also commercial boxes that will convert the RS-232 signals to a USB (Universal Serial Bus) connection. These conversion boxes require a PC software driver so that the PC rig control software will think it is still talking to an RS-232 port.

There are quite a few transceiver to computer interface boxes available – make a Google search to find various models. Currently, I think one of the best price for features value is with the SignaLink USB box from tigertronics.com.

The most modern transceivers will skip the RS-232 connector completely, and provide a direct USB connection from transceiver to computer, along with appropriate drivers.

Rig control via CAT usually uses a different set of commands for each brand of radio. Modern software that uses rig control provide settings that can work with a very large number of radios. Some will even interface to the rig via software protocols with other software. For example, WSJT-X can communicate directly to a radio, or via the CAT interface of Ham Radio Deluxe or DXLab Suite.

Audio Interface

If you also want to use digital modes such as PSK31 or FT8, you also need to connect your computer to the audio input and output of your transceiver. Formerly, the audio connections were made directly from the computer’s audio out and in jacks to the radio’s jacks. This works, but is touchy when setting audio levels, and can make it difficult to also get the normal audio output for computer sounds or music.

The current boxes such as the SignaLink and direct USB connection include independent audio pathways, and make the whole process easier.

Summary

Modern Ham Rigs can be controlled via a CAT interface. Connecting computer to the radio can be done directly via a computer USB cable, or via one of several interface boxes. The various ham apps that provide rig control provide settings to work with different models and brands of radios.

A PC has become an essential part of any Ham Shack. This article has some tips for selecting an excellent computer for your station.

I think that often ham radio stations end up with old, left-over computers. While that isn’t the worst thing in the world, that can mean you end up with an under-powered computer running obsolete versions of the operating system. Given the many choices for computers available today (early 2018), I think one should put as much thought into the computer your station uses as you put into the radios you have.

I’ve recently replaced the computer I use for my Icom IC-7300 based station. I had been using a 2010 era notebook with a faulty display to drive an old monitor. While it does seem that the notebook’s CPU was fast enough, it was not sleeping and waking up properly, and the narrow monitor was limiting. The disk drive was also a bit slow. So that setup was adequate, but limiting. So I decided the time had come for a new computer.

Just a note: I have degrees in Computer Engineering and Computer Science, and because that is my profession, I’ve always had cutting edge computer hardware. For my day to day professional use, I’ve preferred Apple Macs for many years. But since my recent return to amateur radio, I’ve concluded that a Windows machine is best for a digital ham shack – mostly based on the availability of more and better software for Windows computers.

So, what are my recommendations for a very good Windows computer for a ham radio station? I’ll start with some basic recommendations for different levels of functionality and performance.

Cost – It is possible to configure a really good computer, including monitor, for your station for $400 or less. An adequate computer can be had for $200.
Desktop vs. Notebook – Which one?
- Notebook – I really don’t like a notebook computer for my station. The screens are small. It is hard to find a physical location to put it. If you are sharing the notebook computer with your other computing needs, then it can be a hassle to move it around and connect and reconnect with the radio interface devices. If you must use a notebook, then at least get an external monitor, keyboard, and mouse.
- Desktop – A traditional desktop computer (usually placed on the floor, actually) is much more suited for a station computer. It also will be considerably cheaper than a notebook for equivalent performance. Putting the actual box on the floor should minimize the space needed. You can get a larger size monitor (I’d say a 20″ monitor at the minimum) for the operating position. Adding a raised arm for the display can free up desktop space. The keyboard and mouse can ideally be on a slide open shelf under the actual desktop, although having them on the desktop is okay if it isn’t too high off the floor. A desktop also allows you to connect your transceiver, antenna rotor, internet, and so on permanently. Depending on just how you use your computer (e.g., full radio control, digital mode software, log entry), it should likely be the center point of your operating position.
Performance – Most ham radio software programs do not require a whole bunch of computing power. If you want to run several apps at the same time, as well as an internet browser, you will find things snappier with a more powerful computer. But you don’t need a high end machine. You probably don’t need a whole bunch of disk storage unless you are also using the computer for photos or videos. A standard rotating disk (7200 RPM, but preferably not 4800 RPM) is likely adequate. However, if you have an SSD system drive, you will quickly become spoiled by its speed.

Technical Performance Specifications

I am going to recommend getting a certified refurbished desktop computer for your shack – details later. But this does mean that it will likely be a year or two old, maybe more. When selecting any computer, you still need to consider performance.

There are four critical parts of a computer that have the most effect on overall computer performance:

CPU Performance – The performance of your computer software will be most affected by its speed, and the number of cores. A 2 to 3 GHz dual core CPU should be adequate, if not overly peppy, for most ham software. A good, easily available benchmark is called PassMark, available at https://www.cpubenchmark.net. I would recommend a PassMark score between 3000 and 8000. Speed is always nice, but you should never need more power than a PassMark score of 8000. The easiest way to find out the benchmark of the processor in a computer you are considering is to simply type its name and clock speed plus the word “benchmark” into Google, and you will almost always find the cpubenchmark.net link in the search results.
For example, searching for “Intel Core i5-3570 3.4GHz Quad-Core” will give this result: PassMark – Intel Core i5-3570 @ 3.40GHz – Price performance
RAM – 4Gb of RAM should be adequate, but get 8Gb if possible. This will allow multiple apps to better run at the same time.
Disk – Ham Apps won’t require a huge amount of disk space. You can probably get by with as little as 250Gb, but more never hurts. Be sure any hard disk is 7200RPM. SSD disks are available for as little as $40 or $50 for 60Mb or 120Mb. That will easily run Windows 10 and a decent number of apps. It is fairly easy to use an SSD as your system disk, and keep your data on a different hard disk.
Graphics – the graphics video hardware is not very critical for most standard word processor apps, or ham radio apps. If you want to play games on your machine, you might consider a more powerful graphic card than is typically found in basic desktops.

You also need to consider the connections supported by your computer.

USB Ports – Any computer you buy now should have at least a couple of USB 3 ports, and 6 to 8 total USB Ports. Most amateur gear will connect to your computer via USB ports.
Internet – Desktop computers commonly connect to the internet via a hardwired connection. If you don’t have a hardwired connection for your computer, then the other option is WiFi. Some desktops don’t have WiFi built in, but you can get USB WiFi adapters for $20 or less.
Monitor – Most monitors support several standards to connect to your computer: HDMI, Display Port, DVI, and VGA. Depending on the age of the computer you end up with, it may or may not have all of these ports.
Front Panel Slots – It can be nice to have an SD card reader built in, but you can get USB SD card readers very cheaply.
DVD Drive – Do you need a DVD drive? Probably not. Almost all software is downloaded these days.

And finally, consider physical attributes. If you’ve decided on a desktop, note that you don’t have to get a traditional giant case computer (unless you have lots of additional hardware boards to add). There are many slim and ultra-slim computers that are typically much smaller and quieter than a big desktop.

Tech Specs Summary

CPU – Ham software does not need lots of CPU power. Web browsers and Windows do. A fairly new dual or quad core should be plenty for a few years. A PassMark score between 3000 and 8000 is best, but as low as 1500 or so should be okay. Visit www.cpubenchmark.net for PassMark scores for specific CPU models.
RAM – The more the better, but 4Gb should be plenty. 2Gb works, but can slow down responsiveness when running multiple programs. 8Gb is great.
Disk – Ham software is not big, including the databases. 250Gb or 500Gb should be plenty, but 1Tb or more is fine. A 7200 RPM disk is best. You can configure a 64Gb SSD plus a larger hard disk cheaply. Windows on the SSD, data on the hard disk.
Graphics – Doesn’t really matter unless you want to game also.
USB Ports – Four or more. At least a couple USB 3.0 ports nice, but current ham USB interfaces are USB 2.0.
Monitor Ports – Display Port and HDMI are the current standard interfaces. VGI and DVI still commonly found. Adapters available for most monitors. At least a 20” HD monitor is recommended. Two monitors are really nice if you have the space.
DVD Drive – who uses them anymore? Won’t hurt to have one.
SD Card slots – nice, but USB adapters are cheap.
Size – You probably don’t need big PCI cards, so a small form factor size is nice.

Recommended System

So, what did I end up with as my “new” station computer. It is an HP 8300 Elite Small Form Factor Desktop Computer (Intel Core i5-3570 3.4GHz Quad-Core, 8GB RAM, 2TB SATA,Windows 10 Pro 64-Bit) (Certified Refurbished) which I found on Amazon.com in late 2017 for about $230. I have been extremely pleased with this refurbished computer.

wa7ewc-computer

I stumbled on the whole realm of “Small Form Factor” refurbished PCs by accident. Turns out if you search Amazon for “Small Form Factor PC certified refurbished”, you will get a pretty big selection of slightly different configurations of mostly HP, Lenovo, and Dell computers. Certified refurbished generally means that they meet basic standards set by Microsoft, and have been upgraded to the latest version of Microsoft Windows 10. Amazon also monitors the standards of Certified Refurbished dealers.

In early 2018, the prices for these computers ranged from $100 (dual core PassMark 1634, 4Gb RAM, 250GB disk, only USB2, and it would perform okay) to $380 for a current year model (quad core PassMark 9305!, 8Gb RAM, 256Gb SSD). Many choices are available with more than adequate specs for less than $200. These easily outperform any notebook computer in that price range by a lot. All things considered, I find these small factor refurbished computers an amazing deal. Add a nice new HD monitor for around $100, and for well under $400, you can have a really high performance PC for your station.

These small form factor PCs are not really limited in performance or connectivity. They will have plenty of USB ports (hopefully with USB 3.0, but that is not critical for rig control, keyboards, etc.), audio in and out. Some of the models a bit older even have Serial Ports if you have any older rig control hardware.

Depending on your desk size, a Small Form Factor PC can be used horizontally on the desk, or vertically underneath. They generally run very quietly. The do have PCI slots, but are limited to small form factor cards.