{"id":995,"date":"2010-04-06T06:11:05","date_gmt":"2010-04-06T10:11:05","guid":{"rendered":"http:\/\/w4kaz.com\/qth\/?p=995"},"modified":"2011-02-16T09:26:02","modified_gmt":"2011-02-16T13:26:02","slug":"home-brew-so2r-box","status":"publish","type":"post","link":"http:\/\/w4kaz.com\/qth\/?p=995","title":{"rendered":"Home Brew SO2R Box"},"content":{"rendered":"

This home brew SO2R controller project follows the “old-n-busted” theory<\/a>, and is based on the design by N6BV in the ARRL Handbook, as well as some input from K4QPL. In summary, it is built around the use of an LPT port for computer control of the CW, PTT, Radio A\/B, and band data. As previously outlined, the LPT port is less expensive and easier to accommodate – even if obsolete.\u00c2\u00a0 Hence “old-n-busted”.\u00c2\u00a0 I expect to be able to bridge the gap to USB at some point by adding a K1EL WinKeyer<\/a>, and the Piexx SO2Rxlat dongle<\/a>.<\/p>\n

The rig control is still accomplished via a serial port for each radio. The LPT parallel port is used for PTT, CW, transmit focus, and band data for one radio. The K2 band data is a separate option not installed in my K2[another void the Piexx SO2Rxlat dongle will solve].<\/p>\n

As it stands now the only parts missing for a conversion to USB device control are the WinKeyer and SO2Rxlat devices. Everything else in the SO2R control chain is home brew.<\/p>\n

There are several resources available that block diagram the components needed inside the shack for SO2R[e.g.,see DL1IAO<\/a>,\u00c2\u00a0 for the W5XD SO2r Box<\/a>]. \u00c2\u00a0 For ease of use and construction, the heart of the SO2R box breaks down into four logical units which were built into three separate boxes.<\/p>\n

Band Decoder:<\/strong><\/em> One of the peripheral boxes will provide automated band switching driven by the logging program[or directly from a radio] by acting as the band decoder.\u00c2\u00a0 Most logging programs provide band data in the “BCD” format, and Yaesu radios provide that format via their hardware dedicated band data outputs.\u00c2\u00a0 The binary coded band data make the design of the decoder relatively simple.\u00c2\u00a0 In hindsight, it seems like a good idea to expand this component’s abilities by using a set of relays to provide for either positive or sinking switching.\u00c2\u00a0 This is a consideration for driving band pass switches or antenna switches, and is also a design factor for home brewing those components.<\/p>\n


<\/p>\n

\"Inside<\/a>

The internal view of the band decoder<\/p><\/div>\n


<\/p>\n

More band decoder photos<\/a>.<\/p>\n

Band decoder schematic. PNG Image<\/a>, PDF file<\/a><\/p>\n

For those looking for an inexpensive band decoder solution, the Unified Microsystems\u00c2\u00a0 band decoder<\/a> looks like a real bargain and could easily be incorporated into a home brew design. To build a band decoder, it is probably better to start off with the Unified Micro unit and build the support hardware around it.<\/p>\n

Audio Switch:<\/strong><\/em> The second is a simple peripheral to the main SO2R box is a simple remote switch. This device itself is simple, yet it really makes the SO2R a lot easier.\u00c2\u00a0 This device was subdivided into two physical component parts.\u00c2\u00a0 The actual relay board that switches the audio was built on its own small pc board and mounted within the SO2R box.\u00c2\u00a0 The user controls are mounted in a small project box.\u00c2\u00a0 The small box sits just above the keyboard on the desktop.<\/p>\n

For my own preferences, it seemed better to have one small “remote” user control box for switching in the heat of battle. The remote has a rotary switch to control the headphone audio, and it can choose either radio individually, stereo with one in each ear, stereo with left and right reversed, or it can be set to have the audio follow the transmit focus.\u00c2\u00a0 It also has a momentary contact switch for each channel, which can be used in stereo mode to listen to either channel for as long as the switch is depressed. The remote switch control is connected via a Cat-5 cable to the SO2R control box.\u00c2\u00a0 The control box and its rats nest of wiring can be placed away from the station controls.<\/p>\n

Remote: <\/em><\/strong>The momentary contact switch feature will soon be enhanced to correct an original construction oversight.\u00c2\u00a0 Parallel connections for the momentary contact switches will be added to allow using a footswitch.\u00c2\u00a0 That will provide hands-free audio switching when in stereo mode.\u00c2\u00a0 That is important, as I need the hands free to type and deal with CW and radio tuning. Hat tip to K4QPL for the idea.<\/p>\n

Remote locating allows both the main SO2R box and the band decoder to be located away from the other major components in the station.\u00c2\u00a0 That highlights the single caveat I experienced – RFI on SSB.\u00c2\u00a0 After experiencing RFI problems during ARRL SS SSB, both of these\u00c2\u00a0 units still need some attention paid to choking RF on the interconnects.\u00c2\u00a0 Re-locating them a bit further from the RF hot spots and coax connections should also help with the RFI.\u00c2\u00a0 Judicious and liberal use of clamp on RFI chokes seems to abate the problem.<\/p>\n

For some reason, the K2 seemed more susceptible to RFI than the Yaesu FT-920.\u00c2\u00a0 The RFI source there turned out to be on the PTT line.\u00c2\u00a0 A combination of ferrites and a diode in the PTT line finally tamed that hotspot.\u00c2\u00a0 Note:\u00c2\u00a0 in the PTT line, the PTT hot is at the radio’s mike connector, and it really didn’t sink into the thick head right away.<\/p>\n


<\/p>\n

\"The<\/a>

W4KAZ SO2R control box<\/p><\/div>\n


<\/p>\n

More SO2R box photos<\/a><\/p>\n

SO2R box schematic\u00c2\u00a0 PNG Image<\/a>,\u00c2\u00a0 PDF file<\/a><\/p>\n

Audio switching schematic\u00c2\u00a0 PNG Image<\/a>,\u00c2\u00a0 PDF file<\/a><\/p>\n

SO2R Box:<\/strong><\/em> The guts of the system all reside in the main SO2R box.\u00c2\u00a0 It has inputs for headphone audio from each radio, CW inputs, PTT inputs, and microphone audio inputs.\u00c2\u00a0 There is also an LPT Db-25 input for connection to the computer.\u00c2\u00a0 The set up is designed to receive control input from the computer LPT port to drive some of the switching and provide band data.<\/p>\n

The main box contains two separate components. Two small perf boards were used to simplify construction.\u00c2\u00a0 One board contains switching for the headphone audio.\u00c2\u00a0 The other board handles switching for the CW, PTT, focus control, and microphone audio.\u00c2\u00a0 The audio is normally switched via the switch remote, but it can also be slaved to follow the logging program’s transmit focus and be controlled from the main SO2R board.<\/p>\n

Future Migration to USB:<\/strong><\/p>\n

In order to migrate to a logging computer with USB ports, it should be a minor change to replace the LPT cable with a USB connection via the Piexx SO2Rxlat device<\/a>.\u00c2\u00a0 By making the components LPT port compliant, the SO2R capability can also remain backward compatible with an older computer that has no USB support, running Writelog.\u00c2\u00a0 Just in case the only option is an ancient junker from someones junk bin.\u00c2\u00a0 The SO2RXlat will also provide band data for both radios via a single LPT DB-25 connector.<\/p>\n

Postmortem:<\/strong><\/p>\n

The total cost in parts was not large.\u00c2\u00a0 The 4401 NPN transistors, relays, connectors, bypass caps and diodes were all generic ‘project part’ items I have been accumulating over the past several years. I have gravitated towards using RCA connectors because of the availability of inexpensive sheilded RCA cables and the low cost of the connectors. The CD2048 IC for the band decoder was a dedicated purchase, and were around $1.98 USD.\u00c2\u00a0 The amount of time put into construction, the biggest real expense, amounted to about 15 total hours, spread over a long period in several hour long increments.\u00c2\u00a0 I spent more time debugging the RFI issues.<\/p>\n

The RFI is probably partly due to using plastic enclosures, but these enclosures were easy to come by.\u00c2\u00a0 In hindsight I would add ferrite beads on to all interconnects inside the boxes.\u00c2\u00a0 The ferrites on the interconnect cables create a bit of additional clutter and impede quick wire pulls. Kludgy.<\/p>\n

The remote switch has since been modified to add a jack for an external switch to concentrate both channels on either the left or right radio.\u00c2\u00a0 This will allow for use of a foot switch and will allow hands-free audio switching.<\/p>\n","protected":false},"excerpt":{"rendered":"

This home brew SO2R controller project follows the “old-n-busted” theory, and is based on the design by N6BV in the ARRL Handbook, as well as some input from K4QPL. In summary, it is built around the use of an LPT port for computer control of the CW, PTT, Radio A\/B, and band data. As previously outlined, the LPT port is less expensive and easier to accommodate – even if obsolete.\u00c2 Hence “old-n-busted”.\u00c2 I expect to be able to bridge the gap to USB at some point by adding a K1EL WinKeyer, and the Piexx SO2Rxlat dongle.<\/p>\n

The rig control is still accomplished via a serial port for each radio. The LPT parallel port is used for PTT, CW, transmit focus, and band data for one radio. The K2 band data is a separate option not installed in my K2[another void the Piexx SO2Rxlat dongle will solve].<\/p>\n

As it stands now the only parts missing for a conversion to USB device control are the WinKeyer and SO2Rxlat devices. Everything else in the SO2R control chain is home brew.<\/p>\n

There are several resources available that block diagram the components needed inside the shack for SO2R[e.g.,see DL1IAO,\u00c2 for the W5XD SO2r Box]. \u00c2 For ease of use and construction, the heart of the SO2R box breaks down into four logical units which were built into three separate boxes.<\/p>\n

Band Decoder: One of the peripheral boxes will provide automated band switching driven by the logging program[or directly from a radio] by acting as the […]<\/p>\n

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