Tag Archives: DIY

TECSUN AN-200 TECSUN AN-200 AM/WM/LW Tunable Medium Wave Loop Antenna (0.5 MHz to 2.34 MHZ)

Informations about the TECSUN AN-200 medium wave loop receiving only antenna.

When I was looking for an inexpensive medium wave loop antenna, remember that I’m leaving near to a major railways station and that noise is a concern to me, loop could only help, I found some adverts about this antenna also sold under GRUNDIG AN-200 name. I decide to buy one to try and use if good enough. Unfortunately I wasn’t able to find any technical informations but frequency range being in the medium wave. So to help future bidders as the best way to get one is on the bay, I dismantle mine and make some mesurements.

The dia of the loop being 270 mms and having 26 turns of 0.8 mm wire closed spaced, the value of the loop must be around 300 uH at 1 MHz, check it by yourself here. I measured 362.2 uH real world.

PSE NOTE THAT THE 3.3mH FIXED INDUCTANCE SEEN ON THE PICTURES DOESN’T BELONG TO THE ORIGINAL AN-200. I PUT THIS COMPONENT TO DETUNE ONE OF MY AN-200 TO THE LONG WAVE BAND..

There is a 2 turns inductive coupling loop inside the main loop which is linked to the jack that can be used if your radio receiver permit it otherwise you will use the classic inductive coupling putting the AN-200 very close to your receiver. It works perfectly for ALL radios having ferrite rod inside.

                                                                The air variable capacitor as a range from 7.74 pf to 268 pf (mine as bought). This range is adjustable a bit on the capacitor itself, so if you find that yours is off the shelf, you can detune a bit the range. I didn’t do it as I didn’t need it.

Now using the freeware LCfreqs that you can find under the usefull tools in my LX2SM software page we can easily compute the value of the real range of your AN-200 if needed. Mine tune from 0.5 MHz to 2.34 MHZ, where it should be thus.

I will recommand this antenna without any doubt. A solid base to add a preamp using a MAR8.

Source: qsl.net lx2sm Home page

Visually tune your HF antenna using an oscilloscope and signal generator

HF antenna tuning

Lots of readers are into toying around with RF and ham radios. One thing that is always of concern is tuning the antenna. New equipment is never cheap, so whenever another option comes along that uses existing test gear it gets our attention. [Alan Wolke] aka [w2aew] covers a process he uses to tune his HF antenna using a signal generator and oscilloscope.

The process is more of a teaching aid than a practical replacement for commercial equipment mostly because proper signal generators and oscilloscopes are large items and sometimes not available or affordable. That said, if you do have such test gear you only need build a simple breakout board containing a form of wheatstone bridge where the unknown Rx is the antenna. Two oscilloscope probes are connected across the bridge balance nodes. Some special care needs to be taken matching probe cable length and 50 ohm input impedance to the oscilloscope. A couple of 1K probe coupling resistors are also needed to prevent affecting the impendence at the hookup points. Once the selected signal is injected you can adjust an antenna tuner until the two voltage waveforms match on the oscilloscope indicating your antenna network is tuned to 50 ohm impedance with no reactance.

Being able to tune your antenna visually can really help you understand what is going on in the turning process; matching not only input impedance but also phase shift indicating inductive or capacitive reactance. Join us after the break to see the video and for information on what’s presented in the second part of [Alan’s] presentation.

The lesson ends at 8:50 but continues ten seconds later with a part 2 presentation “Estimating the complex impedance of the antenna”.

Via : hackaday.com