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Author Topic: Remotely controlled radio  (Read 434 times)
N7TXH
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Posts: 22




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« on: June 30, 2003, 05:58:40 AM »

Some radios such as the Elecraft K2 can be remotely controlled by a computer. My question is how far away can the radio be from the computer? If I am not mistaken the maximum distance for an RS-232 serial cable is about 50 feet. I want to put my radio farther away than that. Possibly 100 feet or even 300 feet away. I have considered several alternatives that might work.

One idea is to place my old computer next to the radio at the remote location. I could then connect my newer radio to my old radio using a CAT5 serial cable. CAT5 ethernet cable has a maximum distance of 100 meters. The two computers would then be networked together  just like they are now. I normally use Linux most of the time. There is Linux software available for controlling the Elecraft K2. Linux and other versions of Unix have built-in features for remotely using a program that is running on a different computer. It should be possible to open a remote xterm window and then use the point-and-click GUI program that would be running on the other Linux box. The Linux program which was designed to control the K-2 could then be run remotely. I assume that I would then be able to remotely do CW and probably other digital modes.

The hardest part would be if I wanted to remotely do SSB voice. How could I remotely transfer my audio signal to the radio? Could that be done? One possible way would be to use GnomeMeeting to send an audio signal to the sound card on the other computer. There is a version of GnomeMetting avaiable for Linux. That should make it possible to transfer the audio to the other computer. However, I am not sure how to transfer the audio to and from the radio itself. I am assuming that GnomeMetting probably uses the sound card on the computer at each end. What kind of cable or adapters would I use to connect to the radio? Surely someone must have done something like this before! If I could only do CW that would actully be ok.

Another alternative would require using only one computer. At least one company makes a device which allows remote serial ports to be connected to a computer using CAT5 ethernet cable. The device works with both Windows, Unix and Linux and to the computer it is supposed to look just like a local serial port. CAT5 ethernet cable has a maximum distance of 100 meters so I would then have several good choices of where to place my radio. With this option I would only be able to do CW and probably other digital modes. I do not know enough about electronics to know how get the audio signal to the remote radio.

Why would I want to place my radio that far from where I live? Well, it is partly because The ARRL General Class License Manual says I need to connect my transmitter to an 8 foot long ground rod. It also says "keep the ground lead as short as possible." I live on the second floor and a short lead is not possible. This building was built on solid granite bedrock with a thin layer of dirt on top. The nearest place I can drive an 8 foot long rod into the ground is about 100 feet away. So, I need to place my transmitter 100 feet away. The ARRL manual does not mention any alternatives. Do I actually need to place my radio 100 feet away? I have not yet purchased the K-2 and do not know much about the radio or using HF. I am also concerned about having to assemble the Elecraft radio myself and am not too confident about that. Why doesn't some manufaturer just build a radio with an ethernet port on the back?

Would the MFJ-931 artificial ground keep me from having to place my radio 100 feet away?
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AA6YQ
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« Reply #1 on: June 30, 2003, 06:12:32 AM »

You can use RS-422 devices to build an "RS-232 extension cord" whose length can be up to 4000 feet. See http://www.arcelect.com/RS422.htm for details.

    73,

       Dave, AA6YQ
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W3JJH
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« Reply #2 on: July 04, 2003, 09:59:03 PM »

The easiest way to accomplish what you want to do is to run an RS-422 serial interface rather than RS-232.

Before you set up your radio for remote operation, be sure that everything you want to control can be remote controlled.  For example, my FT-990 is can be partially controlled over a serial link.  I can set frequency and mode--enough stuff so that I can keep my face away from the radio most of the time while contesting, but I still need it nearby for certain manual functions.  On the other hand, my Argonaut V is fully remote-controlable.  Only the mic gain and receiver af gain are left under manual control, and, if I use the radio's line in and line out, I could have a mic preamp and audio power amp with volume controls at the control point.

Can you control enough functions on your radio to make remote control worthwhile?
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N7TXH
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Posts: 22




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« Reply #3 on: July 05, 2003, 02:07:00 AM »

I have been thinking this problem over and have finally decided to not setup my radio at a remote location. I will just use a nearby tree for the antenna. I will try doing that despite my second floor location in a building that is sitting on hard granite rock. I now plan to build a 1/4 wave multi-wire antenna with above ground radials.

I will do my best to try and find a place to bury a ground wire or drive a ground rod into the ground. There is a manhole on our property about 50 feet away. The manhole is probably about 3 or 4 feet deep, so that would be a relatively deep spot for a ground rod. A plumber wants me to dig up a sewer pipe near there with our old backhoe, so if that is not too far away, perhaps I could place a ground rod near there. Maybe I could even find a spot slightly closer.
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