Medium Wave DX Receiver - 0.5 to 1.7 MHz
The photo opposite shows what you can do with a Lazy Susan and a 16" Embroidery Hoop! This loop antennae work very well on the Medium Wave band, providing good gain, directivity and noise rejection. I built a small receiver optimised for the medium wave band using the loop antenna for front-end tuned circuit selectivity. Some of the design objectives were:
- Portability - I want to be able to operate this on the top of a hill
- Simple receiver tuning - I do not want lots of tuning and gain controls; preferably a single tuning knob
- Front-end performance sufficient to avoid overloading with local stations. There are not many high power radio stations in NZ. I live about 20 km from the 50 kW 2YA transmitter in Titahi Bay, and this doesn't cause too many problems.
The biggest challenge is the mechanical design of the loop so it can rotate freely in x and y axes. I don't have access to tools or materials to copy the Kiwa MW loop. The 16" loop built here isn't bad. I will describe the construction and design decisions below. A larger loop would be more sensitive, but less portable (see design objectives above).
Block Diagram
The block diagram of the receiver is shown above. I constructed the loop antenna first and verified that it tuned across the entire band from 500 kHz to 1.7 MHz. The tuned loop is effectively the RF tuned circuit for the receiver. The rest is a standard dual conversion superhet. The main IF filter is at 455 kHz - it is hard to build or buy good AM ceramic or crystal filters at any other frequency. I did not want to use 1.6 MHz as I wanted coverage to at least 1,680 kHz; and 9 MHz or 10.7 MHz requires a much higher VCO. The 2.455 MHz IF frequency is a trade-off allowing for a cheap 2 MHz resonator in the second oscillator - an IF in the range of 2 - 3 MHz is good as it is high enough to eliminate image breakthrough whilst low enough to simplify VCO design. With the 2.455 MHz IF, the oscillator tunes from 2.955 MHz - 4.155 MHz (VCO actually allows coverage to 1.8 MHz with a count of 4255, but the loop tops out at just over 1.7 MHz so I limit this in software). The image band is therefore 5,410 - 6,610 MHz in the shortwave band and I didn't experience any breakthrough problems with the MW loop antenna in my area. I have used a couple of ICs in this receiver that I had in my junk box but will now be difficult to obtain - the Plessey SL6440 mixers are easy to use and high performance, but no longer obtainable. The AD831 may be an alternative. Similarly, the MC145151-2 phase-locked loop is also hard to get (try Digikey). A serial load PLL would be easier to use - I used the parallel loading chip with an external 14 bit counter clocked from the micro because I had a MC145151 available. The microprocessor reads a rotary encoder for tuning, clocks the 14 bit counter and displays the frequency on a standard LCD display. It also reads the AGC voltage for a simple bar graph display of signal strength on the LCD. To minimise tuning controls I wanted to tune the loop antenna using a voltage generated by the micro - but when I plotted tuning voltage versus loop resonant frequency (see below) the graph was non-linear and could not easily be approximated by a mathematical equation (I tried 3rd order polynomials, but required 5th to 7th order to get the fit I wanted). The voltage needs to be within about 20 mV to peak reception of distant stations. I initially tried approximating the curve with three straight lines and this worked reasonably well, but subsequently used a lookup table in the PICAXE EEPROM memory. This sets tuning withing 20 - 50 mv, and a fine tuning control is provided on the loop to tweak the signal when DXing and to cover any changes with temperature/humidity.
The loop provides good front-end gain, and with the SL6440 mixers (0 dB conversion loss) not many amplification stages are needed through the receiver. One consequence of this is limited AGC range, and a PIN diode attenuator was necessary at the front-end to reduce the gain on large local signals. I measure several hundred millivolts output from the loop when it is tuned to 2YA, my local 50 kW station on 567 kHz.
Loop Antenna
There are many loop antenna designs. Bigger is usually better. They are directional, so they need to be able to rotate, preferable in both x and y axes. For practical reasons I wanted to restrict the loop to 15 - 20 inches (40 - 50 cm). This loop is not as sensitive as my old 40 inch square box loop, but is sturdier and more portable. I did some initial experiments with regenerative windings for Q-multiplier control (as with the Kiwa loop) but I didn't find the additional complexity and tweaking controls were warranted. The key points to my design are:
- Use of a 16" embroidery hoop. This provides a sturdy wooden frame for the windings, though it would have been nice if it was a bit wider (2 cm is only just enough for 12 turns of wire). The large metal bolts are removed and I used a small piece of wood to secure the outer frame in place (see photo above).
- Balanced loop design (refer circuit below). The loop has 12 turns of wire with a centre-tap, and a balanced amplifier. This aids noise rejection.
- I used 6.5 mm stereo phono plugs and sockets as the axle/bearings for the loop to rotate in the y-axis. Two phono plugs are glued to the embroidery hoop spaced 180 degrees around the hoop. The stereo socket provides 3 electrical connections for the loop winding. The loop can be rotated round and round without getting any wires in a tangle. Phono plugs are not intended to be used this way, and I am not sure what life can be expected. They provide stiffness, so the loop stays in place at any angle. I did not experience any electrical noise when rotated, but recommend buying good quality phono plugs and sockets for this application if you are duplicating my design.
- For x-axis rotation I used a Lazy Susan, with another 6.5 mm phono plug/socket exactly in the centre of the upper and lower pieces of wood to which the Lazy Susan is attached. This provides 3 electrical connections, and allows the loop to be rotated in either direction in both x and y axes without any wires getting tangled. The Lazy Susan has good quality ball bearings. No RF noise occurs when it is rotating.
The Lazy Susan and embroidery hoops can be picked up from craft shops. Alignment is a little tricky and required to ensure smooth rotation. The loop amplifier is attached to one of the loop supports. It requires power from the receiver, which is supplied via the centre of the coax (see circuit diagram below). The loop operates in two modes (switch on side of loop amplifier):
- Manual tuning - in this mode the potentiometer tunes the loop (varactor diode) over the full range from 500 kHz to just over 1700 kHz.
- Auto tuning - the microprocessor sets the varactor voltage to within about 200 mV of resonance, and the potentiometer provides a range of about ±400 mV allowing fine tweaking. The microprocessor tuning is sufficient for single knob tuning for all local stations across the MW band; tweaking is required only for weak stations.
Three wires are therefore required: earth, loop output (centre of coax which is also used to provide voltage to the loop), and tuning voltage from the microprocessor DAC.
The loop amplifier is a balanced emitter follower, providing impedance matching and current gain, but no voltage gain. The output of the resonant loop is an excellent RF signal and further amplification is unnecessary before the first mixers and IF filters.
Full Circuit
Click here for full circuit diagram (281 kB). As shown in the photo above, the main receiver was built "dead-ant" style using a single-sided PCB as the base and earth ground plane. This looks awful, but was quick to assemble and ideal for experimentation and circuit changes. This method does not work well for SMD and SOIC chips which are required for the PLL circuitry, and these components were mounted on a small PCB mounted vertically along with the rotary encoder tuning knob. As shown above, the PLL, micro and LCD circuitry were screened from the receiver with a small aluminium plate.
I mentioned previously that some of the ICs used were because I had them in my junk box, and they could be hard to source if you are trying to duplicate my design.
The loop uses varactor diode tuning, the MV1662 covers 20 pF - 560 pF with 0.5 - 12 Volts. The 12 turn 16" loop has an inductance of about 168 µH. This provides coverage from 500 kHz to over 1,700 kHz without further range switching. The emitter resistors of the J310 FETs were optimised for balance so identical current flows through each FET. The FETs match the high impedance of the loop winding to the low impedance of the coax and receiver input (50 Ohm), but do not provide additional voltage gain (the circuit for the loop amplifier was stolen from one of the designs on the referenced loop pages). I measure several hundred millivolts of signal at certain frequencies at the loop output, so further voltage gain seems unnecessary in the RF stages where overloading can easily occur and degrade receiver performance.
A simple single PIN diode attenuator is inserted between the loop and first mixer. This was to reduce the gain on strong local stations. Whilst I was not experiencing overloading of the SL6440 mixer, the AGC could not cope without it. The AGC is roughly configured to activate the PIN diode on strong local signals that cause the AGC voltage to drop below about 2.8 Volts.
The SL6440 is an excellent little mixer IC that is unfortunately no longer available. It has +30 dBm 3rd order intercept point, and I have experienced no intermodulation problems in my location. I have used a programming current of 25 mA (resulting in about 60 mA total drawn by each SL6440) so it does suck up the juice, but has a small conversion gain in differential output configuration (20 log 2.Rl.Ip = 8 dB) and requires low oscillator injection (250 mV rms).
The 1st IF filter is made with home-wound inductors for 2.455 MHz. In all there are 3 x 14 µH inductors (two in the filter and one in the drain of the 1st IF MOSFET). The bandwidth is wide (about ±100 kHz at 60 dB points). To aid with the design of the 3rd order Butterworth filter I used the program from AADE which produced the following graph (not too different from actual measured performance). There is a small insertion loss. This is quite wide even for a "roofing filter". Unfortunately ladder crystal designs are far too narrow for AM work without a lot of fiddling around (easy to make a 1 kHz wide filter with surplus crystals, not so easy to make one 10 - 20 kHz wide).
I used a single MOSFET as the 1st IF amplifier, with source held about 2.5 Volts above ground so that AGC action allows plenty of gain reduction. The 1st IF amplifier feeds a second SL6440 mixer (probably an overkill for this position, but I had one in my junk box), which has a 2 MHz reference oscillator. I was able to use a 2 MHz ceramic resonator, rather than a crystal, as the reference source. The oscillator buffer amplifier needs to be attenuated to avoid over-driving the SL6440. A simple diplexer network is used to match the SL6440 50 Ohm broadband output to the LC-6F 455 kHz filter. This was salvaged from an FRG7, and has 8 kHz bandwidth (insertion loss about 3 dB with 2 k terminations). From past experience I have found that narrow filters can severely compromise audio quality (SSB filters are no good), but the selectivity of the receiver is not sufficient, for example, to listen to a weak station 9 kHz either side of a local station. This is no different to many commercial receivers including my old FRG7.
The second IF amplifier is a MOSFET identical to the first. I uplifted the circuit for the pseudo-synchronous demodulator from a W7AAZ design (published by Wes Hayward in Experimental Methods in RF Design, page 6.19). The NE602/SA602 mixer operates with a low signal level (tens of millivolts), mixing the signal with itself to produce audio which is amplifier by the Op Amp differential amplifier. I dropped the gain (from around 150 in the original circuit) to around 15 - the circuit demodulates at a low signal level and therefore removes the need for additional IF amplification. The audio output feeds an LM383T with plenty of signal. Typical circuits for the LM383T have a gain of 100, but I had to drop this to 22 and add the feedback network for stable operation at this gain. The LM383T delivers plenty of audio output into a small speaker mounted at the back of the wooden case. Good audio level and quality makes all the difference to a radio receiver.
The AGC is audio derived, and empirically set to reduce the gain of the two MOSFET IF amplifier stages as the signal level increases. As noted previously, I added in a PIN diode attenuator for additional gain reduction for my local stations. Each MOSFET has a gain control range of about 30 - 40 dB, so the two MOSFET stages alone are not going to cover the full dynamic range the receiver is expected to cope with.
Phase Locked Loop
The MC145151 provides reference oscillator, divide-by-N counter and phase detector. For 1 kHz tuning steps I found it most convenient to use an 8,192 kHz reference crystal and RA, RB, RC set for 8192. An alternative would be a 2,048 or 1,024 kHz reference crystal. I had to use an external 14 bit counter (4 x CD4516 CMOS binary counters) to hold the divisor. A parallel loading PLL has the advantage of easy testing using external switch, which I used during initial testing. However, once the micro is connected up serial loading is much easier. The counter needs to count between 2,959 (= 504 kHz) and 4,156 (1,701 kHz). The Preset Enable line is used to set the initial count to 3,454 (= 999 kHz, just subtract the IF frequency of 2,455). As the micro reads the rotary encoder, it clocks the counter either up or down in response to user input. As this is all under micro control the counter cannot get out of step with LCD display. I intended to use the ØR and ØV outputs and an active loop filter, and whilst this worked there was strong 1 kHz feed-through no matter how I adjusted loop parameters. I didn't spend too much time trying to fix this, but there appeared to be 1 kHz signal coming through one of the ØV outputs (asymmetrically) even at lock. The P/D output worked perfectly, though it is harder to calculate the loop filter components. The values shown are for zeta (damping) of 1, and wn of 628 rad/s (one tenth of the 1 kHz reference frequency). As the output of the P/D is limited to the voltage range of the MC145151 (ie 5 Volts) it was necessary to amplify the signal by a factor of 2 for the VCO using the CA3130AE (rail-to-rail) Op Amp. The VCO covers the range 2,955 kHz (0.475 Volts) - 4,255 kHz (6.8 Volts). The Lock Detect (LD) signal of the PLL is not used for receiver muting during tuning as lock time is small with a 628 rad/s loop response time (ie should lock in 20 - 30 ms for small frequency changes).
The MC145151-2 is a surface mount component with 28 small pins, and requires a PCB for mounting and connectivity to the many small pins.
Microcontroller
Whilst a PIC micro would provide more efficient coding, a PICAXE is much quicker and easier to program. The PICAXE-18X has enough inputs and outputs and program space, with pins and memory to spare. The full code can be downloaded here. I had an ALPS EC16B rotary encoder in my junk box - it isn't anything fancy, and as it is mechanical I used some RC networks and Schmitt trigger inverters to ensure full debouncing. The PICAXE does have an interrupt command (but no PUSH or POP instructions!), and this was used to read the rotary encoder. Execution on the PICAXE is slow (cycle time about 250 µs) compared to a raw PIC micro, and updating the display at 2400 baud can take a while. Fast rotation of the dial causes a count to be lodged in a buffer which is subsequently emptied in the micro's own good time. Note that the 14 bit counter is clocked one count at a time, so with 9 kHz step size one click of the rotary encoder requires the counter to be adjusted up or down by 9 counts, and then an update of the LCD display. The dial can be rotated faster than the LCD can be updated, but this is handled in the code by emptying the interrupt buffer and updating the LCD display with multiples of the step size. By this I mean that when the micro reads the rotary encoder interrupt buffer count, if there have been 6 clicks of the dial then the display and counter frequency is immediately adjusted by 6 * step size. In practice the display appears to update smoothly when the dial is rotated quickly.
The PICAXE LCD display module is used, which is easy to write to (but at 2400 baud) and needs only one output line. However, I recommend a backlit LCD display (the PICAXE LCD default module is not backlit) if you are duplicating my design. The PICAXE also drives a little 12-bit DAC for tuning the loop antenna (by little I am referring to the SOIC package it comes in). It is easy to use, but its output is 5 V max so is doubled using a CA3130AE Op Amp (rail-to-rail device). Initially I used 3 straight line approximations of the actual V-F curve for the loop to generate the tuning voltage for the loop based on an error of no more than 200 mV from ideal. These straight line approximations worked reasonably well, just falling off at the extremeties on each end of the band.:
- For f < 725 kHz, DAC = f * 41 / 10 - 1920
- For 725 < f < 1630 kHz, DAC = f * 23 / 10 - 620
- For f > 1630 kHz, DAC = f * 6 - 6610
(where f is in kHz, ie for f = 999 kHz, DAC = 1677, which is 2.048 Volts and subsequently multiplied by 2 = 4.096 Volts. The exact voltage for resonance I measured to be 4.17 Volts at 999 kHz). I subsequently decided that this wasn't good enough, and so I stored a look-up table in the EEPROM memory of the PICAXE using 134 locations (9 kHz intervals from 501 kHz to 1701 kHz). I store 8-bit values (downloaded via the PICAXE EEROM statement - refer to the code) and expand to 12-bit for output via the DAC. I use simple straight line interpolation for 1 kHz intervals between the 9 kHz values. This works reasonably well, with the tweaking control approximately centre position as I tune across the band. The tweaking control is useful for weak stations, and is there to compensate for any temperature or component aging variations.
The EEPROM memory in the PICAXE is used to store the current frequency of the receiver and survives power-off. On first power-on the frequency is set to 999 kHz. Thereafter, the last current frequency is read from EEPROM on power-on, and the counter adjusted up or down in 1 kHz steps - at the extremes of the frequency range this can result in a short start-up delay, but is hardly noticeable. (The counter is clocked with 10 µs pulses but my code could be revised for more efficient operation as there is probably 1 - 2 ms per count, which could be 700 - 800 to count from 999 to the extremity of the frequency range. I may revise this bit of code).
Other than the tuning control, there is only a step size switch for 1 kHz or 9 kHz (the default) tuning increments.
The LCD display is also used to display a simple s-meter bar graph showing signal strength from the AGC line. The AGC line varies from about 4.4 Volts at no signal to about 2.2 Volts at max signal. There are 6 bars used on the LCD display, so this is about 0.36 Volts per bar, or a value of about 18 for an 8-bit 5 Volt ADC (in the PICAXE). The main program loop for the PICAXE is:
- Check step size switch
- Read AGC line and update s-meter display
- Check rotary encoder buffer and update LCD display
Usage
The loop receiver pulls in at least as many stations as my FRG7 with long-wire external antenna. I haven't experienced any intermodulation or image problems, but there are difficulties tuning in to stations immediately adjacent to local stations (as with most receivers of this class). I don't have the necessary test equipment to publish accurate performance information. The table below lists current NZ Medium Wave stations, most of which can be heard at night (the frequencies highlighted in blue are currently vacant NZ frequency slots, and therefore good locations for hearing foreign stations). Stations do come and go so this list may not be 100% up-to-date, check AsianWaves or the World Radio TV Handbook. Nobody in NZ seems to want to use 666 kHz frequency! Foreign stations are just audible on 684 kHz at night (I think this is Fiji). I have also weakly detected a station at night in the low power band on 1683 kHz, probably Sydney.
| kHz | Location | Call | Owner | Power | kHz | Location | Call | Owner | Power | |
| 531 | Henderson | Pacific Radio | 5 kW | 1080 | Henderson | 1ZB | NewstalkZB | 10 kW | ||
| 531 | Alexandra | More FM Central Otago | 2 kW | 1089 | Palmerston North | Radio sport | 2.5 kW | |||
| 531 | Mt Vic tunnel | Transit NZ | ?? mW | 1098 | Christchurch | 3ZB | Radio NZ | 5 kW | ||
| 540 | Taranaki | 2XV | Radio Rhema | 4 kW | 1107 | Papamoa | Radio live | 1 kW | ||
| 540 | Tauranga | 1XC | Radio Rhema | 5 kW | 1116 | Nelson | 2YX | National Radio | 2.5 kW | |
| 549 | Kaitaia | Radio Rhema | 2 kW | 1125 | Dunedin | Radio Hauraki | 0.5 kW | |||
| 549 | Hastings | Radio trackside | 1 kW | 1125 | Napier | Radio sport | 1 kW | |||
| 549 | Stoke, Nelson | Radio sport | 2 kW | 1134 | Queenstown | 4YQ | National Radio | 2 kW | ||
| 558 | Invercargill | Radio sport | 5 kW | 1143 | Hamilton | 1YW | National Radio | 2 kW | ||
| 567 | Titahi Bay | 2YA | National Radio | 50 kW | 1152 | Timaru | 3ZC | NewstalkZB | 2 kW | |
| 576 | Hamilton | Radio Rhema | 2 kW | 1161 | Titahi Bay | 2XM | Te Reo (Maori) | 5 kW | ||
| 585 | Gisborne | 2XR | Radio Ngati Porou | 2 kW | 1170 | Waitomo | 1ZW | Radio Waitomo | 0.4 kW | |
| 585 | Blenheim | Radio Rhema ?? | 1170 | Invercargill | ?? | 2 kW | ||||
| 594 | Timaru | 3XL | Radio Rhema | 5 kW | 1179 | Henderson | Te Reo (Maori) | 5 kW | ||
| 594 | Wanganui | Radio Rhema | 2 kW | 1188 | Rotorua | 1YR | National Radio | 0.4 kW | ||
| 603 | Henderson | Radia Waatea | 5 kW | 1197 | Wanganui | 2ZW | NewstalkZB | 2 kW | ||
| 612 | Christchurch | 3XG | Radio Rhema | 2 kW | 1206 | Dunedin | 4XO | Radio trackside | 2 kW | |
| 612 | New Plymouth | Radio Rhema ?? | 1206 | Hamilton | 1XHC | Comm. Access Radio | 0.5 kW | |||
| 621 | Dunedin | 4XG | Radio Rhema | 2 kW | 1215 | Kaikohe | 1ZE | NewstalkZB | 2 kW | |
| 621 | Whangarei | Radio Rhema | 2 kW | 1224 | Invercargill | 4XF | More FM | 2 kW | ||
| 630 | Hastings | 2YZ | National Radio | 10 kW | 1233 | Horokiwi | Solid Gold FM | 2 kW | ||
| 639 | Alexandra | 4YW | National Radio | 2 kW | 1242 | Whakatane | 1XX | Radio Whakatane | 2 kW | |
| 648 | Gisborne | 2XC | Radio Rhema | 2 kW | 1242 | Murapara | 1XX | Radio Whakatane | 0.1 kW | |
| 648 | Greymouth | Radio Rhema ?? | 1242 | Timaru | Radio trackside | 1 kW | ||||
| 657 | Tauranga | 2YC | National Radio | ?? | 1251 | Henderson | 1XG | Radio Rhema | 5 kW | |
| 657 | Titahi Bay | National Radio | 50 kW | 1260 | Christchurch | 3XA | Radio trackside | 5 kW | ||
| 666 | 1269 | Nelson | 2ZT | Classic Hits | 0.4 kW | |||||
| 675 | Christchurch | 3YA | National Radio | 10 kW | 1278 | Taranaki | NewstalkZB | 2.5 kW | ||
| 684 | 1278 | Napier | 2ZC | NewstalkZB | 2 kW | |||||
| 693 | Dunedin | Radio sport | 5 kW | 1287 | Westport | 3ZW | Radio sport | 2 kW | ||
| 702 | Henderson | 1XP | Radio live | 10 kW | 1296 | Hamilton | 1ZH | NewstalkZB | 2.5 kW | |
| 702 | Rotorua | NewstalkZB | 0.4 kW | 1305 | Dunedin | 4XD | Radio Dunedin | 2.5 kW | ||
| 711 | Horokiwi | 2XP | Radio sport | 5 kW | 1314 | Gisborne | 2YW | National Radio | 2 kW | |
| 720 | Invercargill | 4YZ | Radio NZ | 10 kW | 1314 | Invercargill | Radio Rhema | 5 kW | ||
| 729 | Otago | 4XX | Classic Gold | 0.1 kW | 1323 | |||||
| 729 | Tokoroa | 1YP | National Radio | 2.5 kW | 1332 | Henderson | Radio sport | 10 kW | ||
| 729 | Whangarei | Radio sport | 2.5 kW | 1341 | Nelson | 2ZN | NewstalkZB | 2 kW | ||
| 738 | Christchurch | Radio live | 5 kW | 1350 | Rotorua | Radio sport | 1 kW | |||
| 747 | Rotorua | NewstalkZB | 0.4 kW | 1359 | New Plymouth | 4XC | The Coast | 2.5 kW | ||
| 756 | Otago | Radio Puketapu | 0.8 kW | 1359 | Queenstown | More FM | 1 kW | |||
| 756 | Henderson | 1YA | National Radio | 10 kW | 1368 | Napier | 1XT | Radio Live | 1 kW | |
| 765 | Hastings | 2XT | Radio Kahungunu | 2.5 kW | 1368 | Tauranga | Village Radio | 0.8 kW | ||
| 774 | New Plymouth | Radio sport | 5 kW | 1377 | Levin | 2XX | Radio Sport | 2 kW | ||
| 783 | Titahi Bay | 2YB | Access Radio | 10 kW | 1386 | Henderson | Radio Tarana (Hindi) | 10 kW | ||
| 792 | Hamilton | Radio sport | 5 kW | 1395 | Oamaru | 4ZW | NewstalkZB | 2 kW | ||
| 801 | Nelson | 2XL | Radio Rhema | 1 kW | 1404 | Invercargill | 4XL | Radio Rhema | 2.5 kW | |
| 810 | Mangere | Radio trust | 5 kW | 1413 | Christchurch | 3XP | Radio Ferrymead | 1 kW | ||
| 810 | Dunedin | 4YA | National Radio | 10 kW | 1413 | Tokoroa | 1ZO | NewstalkZB | 1 kW | |
| 819 | Tauranga | 1YZ | National Radio | 10 kW | 1422 | |||||
| 828 | Palmerston North | 2XS | Radio trackside | 2 kW | 1431 | Napier | 2XKC | Radio Kidnappers | 2 kW | |
| 837 | Kaitaia | 1YX | National Radio | 2 kW | 1440 | Lawrence | Goldrush | 0.1 kW | ||
| 837 | Whangarei | 1YX | National Radio | 2.5 kW | 1440 | Tauranga | 1XK | Te Reo (Maori) | 0.2 kW | |
| 846 | Masterton | NewstalkZB | 2 kW | 1449 | Kairanga | 2YM | National Radio | 2.5 kW | ||
| 855 | Hamilton | 1XH | Radio Rhema | 2 kW | 1458 | Westport | 3YW | National Radio | 2.5 kW | |
| 864 | Invercargill | 4ZA | NewstalkZB | 10 kW | 1467 | |||||
| 873 | Ashburton | 3ZE | NewstalkZB | 1 kW | 1476 | Henderson | 1XD | Radio trackside | 5 kW | |
| 873 | Tauranga | Radio trackside | 1 kW | 1485 | Gisborne | Radio trackside | 1 kW | |||
| 882 | Henderson | 1YC | National Radio | 10 kW | 1494 | Hamilton | National Radio | 2.5 kW | ||
| 891 | Horokiwi | 2XW | The Breeze | 5 kW | 1494 | Timaru | Radio sport | 5 kW | ||
| 900 | Dunedin | 4YC | Radio NZ | 10 kW | 1503 | Christchurch | Radio sport | 2.5 kW | ||
| 900 | Whangarei | Coast | 2.5 kW | 1503 | Horokiwi | Radio sport | 5 kW | |||
| 909 | Hastings | 2XD | Radio NZ | 5 kW | 1512 | Taumaranui | 1ZU | Classic Hits | 1 kW | |
| 918 | New Plymouth | National Radio | 2.5 kW | 1521 | Tauranga | Radio sport | 1 kW | |||
| 918 | Timaru | 3YT | National Radio | 2.5 kW | 1530 | Napier | 2YP | The Coast | 1 kW | |
| 927 | Palmerston North | 2ZA | NewstalkZB | 2 kW | 1539 | Blenheim | 2ZE | Radio sport | 1 kW | |
| 936 | Henderson | Chinese broadcasting | 1 kW | 1548 | Palmerston North | The Coast | 1 kW | |||
| 945 | Gisborne | 2ZG | NewstalkZB | 2 kW | 1548 | Rotorua | 1XN | Radio Pacific | 0.9 kW | |
| 954 | Hamilton | 1XW | Radio trackside | 2 kW | 1557 | Hawera | 2ZH | NewstalkZB | 2 kW | |
| 963 | Christchurch | 3YC | National Radio | 10 kW | 1566 | |||||
| 972 | Horokiwi | 2XG | Radio Rhema | 5 kW | 1575 | Dunedin | 4XS | Hills AM | 2.5 kW | |
| 981 | Timaru | Radio Rhema | 2.5 kW | 1584 | Picton | 2ZF | Classic Hits | 0.4 kW | ||
| 981 | Kaikohe | 1YE | National Radio | 2 kW | 1593 | Henderson | Radio Samoa | 5 kW | ||
| 990 | Mangere | Radio Apna | 1 kW | 1593 | Christchurch | The Coast | 2.5 kW | |||
| 990 | Nelson | More FM | 1 kW | 1602 | Levin | 2XA | Radio Reading Service | 2.5 kW | ||
| 999 | Palmerston North | Manawatu Access Radio | 1.5 kW | 1611 | ||||||
| 1008 | Tauranga | 1ZD | NewstalkZB | 10 kW | 1620 | |||||
| 1017 | Christchurch | Radio Hauraki | 2.5 kW | 1629 | ||||||
| 1026 | Invercargill | World Bible Radio | 1 kW | 1638 | ||||||
| 1026 | Kaitaia | 1ZK | NewstalkZB | 2 kW | 1647 | |||||
| 1026 | Whangarei | 1ZN | NewstalkZB | 2 kW | 1656 | |||||
| 1035 | Titahi Bay | 2ZB | NewstalkZB | 20 kW | 1665 | |||||
| 1044 | Highcliff, Dunedin | 4ZB | National Radio | 5 kW | 1674 | |||||
| 1053 | New Plymouth | 2ZP | NewstalkZB | 2 kW | 1683 | |||||
| 1062 | Wanganui | Radio sport | 1 kW | 1692 | ||||||
| 1071 | Ashburton | Radio trackside | 1 kW | 1701 | ||||||
| 1071 | Masterton | 2YE | National Radio | 2.5 kW |
© In the Light, 17 September, 2009 , Disclaimer, Son of Suckerfish drop-downs from HTML dog