Audio Attenuator for PSK/RTTY/SSTV/...

Been using a RIGblaster plug  & play interface between the computer and the radio for digital modes. Works OK, but to get the proper output level to drive the radio, the computer volume needed to be quite low, around 10%. Since the same computer is also used to play music, I always had to adjust the volume way down for radio use, then back up to listen to music.

Finally got around to build a simple attenuator. The junk box happened to contain a 4k potentiometer with nice knob, so I used that. Computer output connects to the pot, and its wiper goes to the RIGblaster. The computer (laptop) output volume is now simply set to "100%", which is easy to reproduce, and the attenuator was once adjusted to give proper audio drive to the radio.

People with more patience should be able to put a smaller trim pot inside the RIGblaster, but I preferred to keep that as is and instead plugging the attenuator in-line.

 In the picture, the pigtail on the right side of the black box goes into the computer's headphone jack. Audio from there is then attenuated, fed via the blue/green plug into the rigblaster and on into the radio.

RIGblaster plug & play needs USB-2

Tried to communicate with a RIGblaster plug & play via Java RXTX.
The Rigblaster is essentially a USB-to-serial converter. All functioned fine on a new Windows 7 computer with 64 bit Java, until suddenly it didn't. The RXTX code hung somewhere in its CommPortIdentifier class that is used to open a port.

Reason turned out the type of USB port. This computer happens to have USB-2 as well as newer USB-3 ports. With USB-2 all is fine, with USB-3 the RXTX library hangs.

RAOTA - What an idea!

Rest Areas on the Air, starting on Nov. 23, 2011:

http://www.ihras.net

Map http://www.tdot.state.tn.us/maintenance/restareas.htm mentions "2 hour parking limit":

The Ultimate AL-811 Tuneup Checklist

Overall Tuneup

1. Amplifier HV, STBY, OFF
2. Adjust Antenna Tuner
3. Set Band Switch
4. Transmitter power low
5. Turn ON. Check Tubes lit, Plate Voltage ~1.7kV, Plate and Grid current 0mA
6. Preset LOAD and PLATE
   

   MHz	LOAD	PLATE
   7.1	2.25	7.5
   14.0	3.0	8.75
   14.15	3.3	8.75
   14.3	3.75	8.75
   18.1	3.3	8.7

   
   
7. Ip, XMT OPR. Check plate current Ip=0mA. Key in SSB mode. Ip~60mA
8. In CW mode, increate Xmtr power until Plate Current 450mA or Grid Current 100mA
9. Tune PLATE, LOAD, PLATE for max power. Keep LOAD a little to the right of max. output power. Stay below 100W input, 450mA plate, 150mA grid.

ALC

1. Set Xmtr power to get about 400W amplifier output
2. Connect ALC line, adjust ALC (back of amplifier) so that output starts to drop a little bit. From now on, Xmtr output is limited to generating 400W amp out.

List of Things

Things to try, buy, finish, ... in no particular order

• "Windspiel" that powers LEDs just for fun
• Steam Engine
• Steam Boat
• Elektric Jet
• P-40
• Auto Gyro
• Float plane
• Segelboot: http://www.victor-model.com, Soling 1 Meter, www.servocity.com for servo gearboxes, http://sourceforge.net/projects/sailcut/
• Oldtimer "Graubele Schulgleiter"
• 40,30,20,17,15 switched dipole
• 2-mot: B-25, DC-3
• Variometer, altimeter, http://www.wingedshadow.com Thermal Scout

Done:

• Traxxas Slash
• Linear Amplifier, abt. 500W
• Marklin "Ticket To Ride" game

APRS Links

• http://www.byonics.com/ - Tiny Trackers
• http://www.findu.com/ - One of the oldest sites?
• http://www.openaprs.net/ - Google Map based
• http://www.openaprs.net/ - Google Map based

QRZ.COM Web Parser Limitations

Writing a web page parser for QRZ.COM recently became harder because you have to log in to see the more detailed information about operator location etc.

That's probably why Ham Radio Deluxe and other programs announced that they'll

stop supporting their QRZ.COM web page parser and instead use only

the QRZ.COM XML interface.

Good news: The interface allows name and country lookup for every

QRZ.COM user.

Bad news: Have to be registered. That's free, but means that all lookups

are traced to your user ID.

For the full information (grid, location, license info, ...) you have

to be a subscribed user, about $25 per year.

May not be that much money considering that QRZ.COM must have considerable

costs for keeping the page running.

Anyway, XML format detail is currently here:

http://www.qrz.com/XML/index.html

Another option might be the FCC ULS data, access to which is described here:

• http://www.n6lhv.net/uls/
• http://wireless.fcc.gov/cgi-bin/wtb-datadump.pl

PSK31 Volume and RF Output

One way to adjust the output that seems straight forward and "works":
Set the FT897 HF power to 100%, then adjust the sound card output such

that the power is only 20 or 30 watts.

Echolink Audio Setup, DTMF

Under Tools/Setup/Audio, the Calibrate button suggested a fine tuning of -94, but with that the DTMF tones were not recognized...

What works:

• Fine tuning: 0 (default)
• Sound card "Microphone" level 50% with "Advanced", "Boost" enabled
• Sound card "Volume" all 100%, master volume around 75..80%

Echolink Network Setup

After installing Echolink, the Firewall/router test failed.

Fix:

1. In Windows firewall (Wireless interface, Properties, Advanced, Firewall, ...) add Exceptions for UDP port 5198 and 5199, i.e. add 2 separate exceptions.
2. In the D-Link DI-614+, add similar exceptions under Home, Advanced, Virtual Server: Traffic from "public port" 5198 needs to go to "private port" 5198, where the "private IP" is the IP of the laptop, like 10.0.104. Again add 2 separate Virtual Servers for 5198 and 5199.

The D-Link setup has the drawback that it's locked to an IP address, so the Laptop should have a fixed IP on the local wireless net.

This post shows how to enable Port Triggering which solves the IP address issue: http://echomac.sourceforge.net/routers.html