ON3JT

I finally bought a networkdrive to be used in my home network. My wife was complaining that all pictures were on the pc downstairs (my shackcomputer) and she want to see them also on the pc in the living room. Time to share the data. But I needed a NAS style disk, not just some usb drive. 

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I came acros the site of IK0VVE with a wonderfull description of a MEPT.
MEPT stands for Manned Experimental Propagation Transmitter and is usually very low power. He uses a crystal oscilator but I find them pretty expensive. So I Looked around the net for programmable oscillators. Those are even more expensive and in the most cases you need a microcontroller to programm them. The oscillators uses I²C for setting the frequency by setting the divider and table lookups, …..

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Hello World,
my last entry was from february last year (exact one year ago) and then everything went quiet. What has happened since?

We sold our appartment and bought a house with a small garden. Early March we were alerted by friends that there was a house for sale in their street. We know about 5 families in that street, all our children attend the same school and and have approximately the same age. After a long weekend calculating and visiting bank sites to learn about loans we mailed our price to the real estate company. Monday morning we were phoned that our bid was accepted. Everything went fast from that moment on. We sold our appartment to my parents in law. In May we signed all papers and we are now the owners of a house. In June and July we moved.

For the hobby it was a bit giving and taking. I now have a separate shack, Measuring only 1,5 by 2,4 meter. I saw the  appartment building as one big antenna mast, that is gone now But I found the remains of a tv arial on the roof of our house. That should be a good anchorpoint to mount my X200 and a wire antenna for HF.
The garden is about 6 by 30m, just big enough to fit a FD4 antenna. The FD4 is almost ready, but the weather hasn’t cooperating lately.

Other projects I would like to to :

• Build me a G7FEK antenna
• Build a end fed half wave 20m vertical.
• Build a small MEPT (see separate post).
• ….

 This article is a reprint from my original article published in 2004. I don’t use the antenna anymore (collecting dust in the basement) but the article will stay here for informational purposes.

I live in an appartment and don’t have the space to put up a large antenna for my Kenwood R1000 receiver.
I knew the excistance of magnetic loops, but I never spent time to take a look at it. Why ? Who knows.

For the main loop I used a soft copper tube, diameter is 10 mm, length about 3 meter.
Try to make a circle (not always easy). A friend of me, Carl ON7NH, has drilled and tapped M3 tread into it. This makes it possible to use solder lips. The entire loop is constructed on a sunday afternoon.
The smaller loop is about 60 cm in length (diameter 1/5 of the main loop), material is 1,5 square mm copperwire.

With the capacitor found in my junkbox, I can tune the loop from 2,9 Mhz till 10 Mhz. Other capacitors will give other tuning ranges, have to experiment here.

This post is taken from my old website. I’m still dismantling that site.

What is PMR446 anyway ?
PMR446 stands for Personal Mobile Radio and is a license free radio in the 446 MHz UHF band. That is about 6 Mhz above the 70cm amateur radio band. There are 8 channels starting at 446.00625 MHz and ending at 446.09375, spaced 12.5 kHz apart.
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Ham radio operators interested digital modes will often use these computer interfaces to automate CW contacts (send morse code from the PC), use the PC soundcard for RTTY and control push-to-talk functions among other things.
Many of the PTT interface drawings  found on the net suffer the same problem. Well it is not really a problem.

Let’s have a look at a typical interface :
You have the RTS and DTR line tied together with diode, then comes a transistor that operates as a switch. And finally the ptt line from you transceiver. So when the RTS or DTR signal goes high, you are on the air. So what is the catch ? Ever booted your computer or used other software besides your regular hamradio soft ? Of course you did and what happened ? My transceiver went in to TX on the wrong antenna / receive converter / mistuned antenna. Luckely the radio was set in SSB and no harm done without modulation. But it could be worse.

So what have I done ?
A simple modification that costs almost nothing : add a simple switch in the PTT line. See the red switch in the interface drawing.

That’s it. When the computer has booted and ready to use, I toggle the switch and can operate the digital modes.

I just noticed in Google Analytics that I passed the 10,000 visitors benchmark. My blog started in March 2008 and I installed Analytics around March 22.
So from March 22 2008 till now (Feb 3 2009) I had 10,381 visitors.
About 75% comes from search engines and merely 18% via other sites. This is a figure that can be better. Work todo !