Hi Adrian, The red LED should glow faintly in normal use but glow brightly if there is a short circuit in the cable or head unit. Due to component tolerances the LED brightness in normal use can vary.

That's a curious problem. If the antenna is mounted high outside it's possible that it could be wind generated static electricity on the loop and cable leaking away to ground once it's connected to th

We've been making the HF Active Loop Antenna for a few years now and whenever we attend radio rallies and hamfests or mention it to other radio amateurs I'm always asked "When are you going to make a

Thanks for all the feedback and comments. Very useful. It's only just the start of the project so there will be a few more prototypes before anything goes into production. The idea was to look first a

I've just run another high power test after modifying the prototype. This time it got through 30 seconds of a 20m JT-65 transmission at 100W before arcing over. In both the tests so far I've been myst

It's certainly interesting trying to get it working. I'll keep at it because I can see that the objective of a loop antenna tuner that can tune a range of loops is worthwhile. I do like your design fo

It's very early in the design project yet so it will be a month or two before we have a transmitting magnetic loop antenna ready for sale. I'm still proving the ideas behind the design, then we have t

Hi John, Thanks for your comments. The current prototype is using LMR400 and N connectors just because they were available and it seemed a good place to start as some commercial loops use it. I'm now

Looking at where I left the new DSP Digi Tracker project I was fairly well on with the PCB design and the firmware was well proven. With the interest shown I'll look at finishing the PCB design and ge

Thanks for all the replies, I'll finish the design and make a small batch. Regarding the 9 pin connector the original Digi Tracker used a 9 pin D type to the Kantronics spec so that it was compatible

To answer some other questions: The Digi Tracker and the proposed DSP Digi Tracker are 1200 bd for VHF operation. Time slotting wasn't included in the firmware, there isn't enough memory left to add i

To get things started I've republished the APRS Messenger Android app on Google Play: APRS Messenger Android on Google Play This app works with both old and new Digi Trackers to act as an igate to sen

I've now rebuilt the prototype loop antenna with substantially thicker copper plates and PTFE sheet for the capacitor. It can now happily withstand 100W of 20m JT-65 carrier without any ill effects an

I've also been looking at the safety aspects of magnetic loop antennas especially regarding the safety clearances. Over the years in several contracts I've been involved in calculating RF safety clear

I should clarify that the maximum RF current figure of 20 mA is for when the antenna metalwork is in contact with the human body i.e. RF burns. Regards Chris G4HYG

I've added a new web page to the CCW web site covering the development so far of the HF magnetic loop antenna. There are some photos of the first prototype and some of the capacitor options. The link

I often get asked which active antenna is best and my usual answer is "It depends on what you want it to do". Running through the antennas: Broadband Active Antenna: This antenna was designed for airb

The amplifier in the HF Active Antenna has very high impedance inputs to match the capacitance of the whip antennas. Running a wire loop between the two inputs wouldn't work very well due to the imped

Recently we have been asked to design a dual diversity SDR receiver for a radio propagation research project. The receiver design was based on two SDR-4+ PCBs using a single oscillator so that the two

I only had an hour to "play" with the receiver after the workshop tests before we shipped it out. The amount of background noise affecting the AGC could be controlled on SSB by adjusting the AGC thres