Radio Interfaces

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This year, the W4IY VHF contest group would like to implement the voice keyer functions within the N1MM contest logging program. This will allow the computer to replace the MFJ VoiceKeyers. Aside from the challanges of getting the program to run and the proper voices loaded, we need to interface the computer's sound card with the radio. As an experiment, we'll use the 432MHz station as a test. If successful, we can expand the concept to the other stations.

I looked at several vendors including West Mountain Radio (RigBlaster), MicroHam and WB2REM's ULI (which I own.) After surveying all the various options, it looks like the interfaces from MicroHam provide the most flexibility. Next, I drew schematics of the 432MHz station, using three of the devices from MicroHam, to make sure the devices would accommodate all of our accessories and acheive the final goal. My requirements changed as I studied the manuals because I learned more about the capabilities.

So which interface box is better? For me - it was the Micro Keyer from MicroHam.

Contents

Basic Requirements

Here are the basic requirements I used to evaluate the interface boxes. The three main goals are 1) accommodate the N1MM voice keyer, 2) transition to USB and 3) simplify the station setup. The basic N1MM setup can be found in the N1MM Setup manual. So the requirements are:

  • Allow the N1MM voice keyer to function
  • Simplify overall all setup and operations
  • Reduce the number of cables
  • Provide galvanic isolation between the computer and rig
  • Implement CW keyer
  • Implement Computer Control
  • Switch to USB to accommodate newer computers
  • Handle the Heil headsets, paddles, footswitch and microphone
  • Accommodate rig/PA/LNA sequencing


The basic configuration for the voice keyer function looks like the following picture. Note how the microphone audio path loops through the sound card. This allows N1MM to 1) mute the mic while playing the DVK voice and 2) keep the mic and playback audio levels consistent.

SO2R5-1.gif


The interface boxes have USB capability, which means we can use newer computers without serial ports. Looking at these boxes, we also find CAT control, PTT control and CW keying. Radio-specific cables are still required, but now the computer connections can be standardized. Plus, the interface boxes can handle Kenwood, Icom and Yaesu control signals, so the interface boxes can be standardized.

Summary - What to buy.

I looked at two options.

Option #1: Go the cheap route. ($120) Use one of the simple audio interfaces, get rid of the DVK and add USB/CAT control. Not a bad option. However, these devices don't handle the microphone audio path or the keyline/foot switch. This keeps the station in the 'kludge' mode, meaning we still need all the extra gear and cables.

Option #2: Add another $150 and simplify. Eliminate the keyer and PA sequencer. Add an audio switch matrix and winkey CW keyer. This provides maximum flexibility for the station and eliminates just about all the extra boxes.

I looked at the Rig Blaster Pro and the Micro Keyer. After a lot of analysis, I decided the the Micro Keyer is better for me because it has better packaging, better configuration software and is designed as a USB device.

I'm not excited about the price ($299,) but I might as well spend the extra $150 for maximum flexibility. I really can't think of anything this interface won't do for me in the future. (Except - provide two external sequenced outputs for the PA and the LNA.)

USB Inteface II

The USB Interface II provides simple audio isolation and a USB interface for CAT/CW. It's pretty simple and on par with the other USB interfaces, like the RigBlaster. It looks like this will work for interfacing the computer's sound card to the radio - plus - provide computer control via the USB interface. At $149, this is very attractive choice. It doesn't really simplify the station setup. There are audio trimmer pots available. (Something the Data Jack doesn't have.)

Requirements

  • Check.pngAllow the N1MM voice keyer to function
  • Xmark.pngSimplify overall all setup and operations - Still requires the external sequencer and you have to connect the mic to the line card.
  • Xmark.pngReduce the number of cables - not really. It adds cables for the audio.
  • Check.pngProvide galvonic isolation between the computer and rig - via transformers and optocouplers
  • Check.pngImplement CW keyer - yes, but relies on computer timing. Good to abou 50wpm.
  • Check.pngImplement Computer Control - Yes, this looks like it works OK.
  • Check.pngSwitch to USB to accommodate newer computers - Yes, meets this requirement.
  • Xmark.pngHandle the Heil headsets, paddles, footswitch and microphone - no, you're on your own.
  • Xmark.pngAccommodate rig/PA/LNA sequencing - no, still requires sequencer.

Diagram - using the USB Interface II

Digi Keyer

This looks like a good interface for digital modes only. It's not a good choice for accommodating the voice keyer. It has it's own sound card, but it doesn't seem to have a connection for the microphone. So audio can't route through the sound card - which means N1MM can't mute the mic.

Requirements

  • Xmark.pngAllow the N1MM voice keyer to function - Not really, because I don't think there is connection for the microphone. The Heil headsets require a preamp.
  • Xmark.pngSimplify overall all setup and operations - It elminates the sound card connects and uses a single USB connection. Can't get any simplier than this, but it can't accommodate the mic.
  • Xmark.pngReduce the number of cables - not really. It adds cables for the audio.
  • Check.pngProvide galvonic isolation between the computer and rig - via transformers and optocouplers
  • Check.pngImplement CW keyer - yes, but relies on computer timing. Good to abou 50wpm.
  • Check.pngImplement Computer Control - Yes, this looks like it works OK.
  • Check.pngSwitch to USB to accommodate newer computers - Yes, meets this requirement.
  • Xmark.pngHandle the Heil headsets, paddles, footswitch and microphone - no, you're on your own.
  • Xmark.pngAccommodate rig/PA/LNA sequencing - no, still requires sequencer.

Diagram - using the Digi Keyer

Micro Keyer

It looks like this device meets all the requirements and provides maximum flexibility for all modes CW, Voice and Digital. The down side is the price. At $299 - it's a little more than I want to spend, but considering it simplies the station, allows N1MM to work, allows for digital modes and has a memory keyer - this seems like the best choice.

Requirements

  • Check.pngAllow the N1MM voice keyer to function - Yes, with lots of options.
  • Check.pngSimplify overall all setup and operations - Still requires audio cables to/from the computer sound card, but it eliminates the keyer and sequencer.
  • Check.pngReduce the number of cables - I think this is the minimum possible. The only better thing would be an internal sound card, like the digi keyer, which would eliminate the cables to/from the computers sound card.
  • Check.pngProvide galvonic isolation between the computer and rig - via transformers and optocouplers
  • Check.pngImplement CW keyer - yes, through WinKey chip.
  • Check.pngImplement Computer Control - Yes, this looks like it works OK.
  • Check.pngSwitch to USB to accommodate newer computers - Yes, meets this requirement.
  • Check.pngHandle the Heil headsets, paddles, footswitch and microphone - Yes - extensive switching matrix.
  • Xmark.pngAccommodate rig/PA/LNA sequencing - Only the PA or LNA. For stations using RF switched, mast mounted preamps, this is OK. However, for stations using high power, which exceeds the limits of the preamp relay, an external sequencer will still be required.

Diagram - using the Micro Keyer

Update - 4/5/07 - I bought the Micro Keyer and interfaced it to my TS-2000. After spending several hours playing with all the options, I'm sure I made the right choice. There were two rough spots - 1) understanding the audio routing matrix and getting the sound cards to work.

Update - 8/13/07 - After much work, I figured out how to eliminate the sequencer for the 440 station. The new software allows for a LNA sequence, instead of a PA sequence. This means, I can use the PA PTT output to unkey/key the preamp and PTT1 on the mic connector to key the rig. The rig keys the PA.

Key concepts

The audio routing can change, depending on the PTT source. Decide how the rig should be keyed, then match up the audio routing with your choice. The mic label in the drawings means the mic connector on the front of the rig, not line in. You can use the templates as a starting point.

Make sure the menu item 50F is set for 1200 baud, not 9600. I'm sure this is the default, but when I tried to get the rig to work with one of the 9600 baud microsats, I changed this setting to 9600. I couldn't get any audio out of the ACC2 connector.

Rig Blaster

West Mountain offers two products with USB interfaces; the Rigblaster Pro and the USB Data Jack. They have a nice product comparison chart on their web site. [1] The Data Jack costs $110 plus another $10 for cables/adapters. The Pro costs $280.

The Data Jack is similar to the USB Interface II in that it isolates the audio lines, provides PTT, CAT Interface and CW keying. It also requires a rig-specific cable and uses the auxiliary jack on the back of the rig. It doesn't have any audio level trim pots available.

The RigBlaster Pro is similar to the Micro Keyer. It looks like West Mountain simply adds a USB/RS-232 converter to their kit, which makes their serial unit work on USB. It also requires a bunch of separate cables, which could be either bad or good, depending on your outlook.