The Kit Support section is to assist those that may be having difficulty constructing or making a Kit work. Most Kits are tested regularly to make sure that there are no issues due to faulty batches of components, or PC boards. Older Kits may have had changes by modifications to improve the performance.
Almost all problems with Kits are due to solder joints being bridged, or components being placed onto the PC board in the wrong location. If you cannot get a Kit working, then please first double check these possible problems first.
RF type Kits can have instability issues when mounted inside a box enclosure of a size which may resonate causing RF instability. Most RF Kits include specific documentation on how to best mount the Kit including the RF cabling to connectors.
If you have trouble with your Kit, Mini-Kits can repair it for you, provided that your kit was assembled to a satisfactory standard. Please Email first before sending any products back for repair. A charge of $33.00 AUD applies, ( Australian Customers Only ) for repairs which will cover minor parts, repairs and return postage. Overseas customers please Email. If a Kit requires extensive work or replacement of components, then you will be contacted with a quotation for the repair.
1/ A 1Mohm resistor was fitted on the input amplifier to drop the audio level when using a line level input. This resistor affects the 50uS Pre-emphasis circuit effectively making it inoperative. It is suggested that the 1Mohm is replaced with a 1Kohm resistor and if the gain needs to be reduced, then change the 270kohm feedback resistor to a smaller value. A 2k2ohm feedback resistor seems about right for line level input. Alternatively replace the 270kohm with a 500K trimpot to adjust the gain. Current Kits have now been upgraded.
2/ A simple modification supplied by Steve VK5SFA to reduce 5.5MHz patterning on the picture, is to replace the 1nF ceramic capacitor on the output to a 100 to 150pF. However the 1nF option for increased gain needs to be fitted to get enough subcarrier output. Current Kits have now been upgraded.
3/ The only fault seen with this Kit was with the LA7051 IC having a short circuit to the top ground plane of the board. Be careful to leave a slight gap between the IC and the top of the board in construction.
4/ Modification to use on 6.5MHz and above, change the 47pF NPO capacitor across the 15uH coil to 33pF or lower. A new ceramic filter for the same frequency also needs to be fitted.
5/ Audio distortion can occur with some SFE ceramic filters. A 560ohm resistor needs to be fitted from the input of the filter to ground. The problem appears to be lack of impedance matching on the output of the SFE Filter. Current Kits have now been updated.
6/ Some Kits have been supplied with 18uH coils instead of 15uH ones. For 5.5 / 5.74 / 6.0MHz a 27pF capacitor for C1 is used, and For 6.5MHz a 22pF for C1.
Discontinued Product No Longer Supported.
1/ There has now been 4 reports of faulty 100pF capacitors in the 6.4MHz oscillator causing low 3.2MHz output from the 4040 IC. The symptom is that the PLL locks initially when turned on, and then goes out of lock in a second or so. The faulty capacitors are Philips miniplates, grey in colour with a 5mm pin spacing. The new replacements are now brown ceramics.
2/ Another problem causing the PLL not to work is a problem with the clearance of IC pins shorting out on the top ground plane of the PC board. It is best not to push the ICs down too far into the PC board before soldering to leave a slight gap.
3/ Display reads ok and shows locked even when the 1250MHz transmitter is turned off. DC output from the TSA5511 to control the PLL sits at around 2 to 3 volts and doesn't shift when tuning. The PIC16F84 was found to be faulty. I tried reprogramming it but it still caused the same problem. A new programmed PIC fixed the fault.
4/ A common fault has been damage to the PIC16F84, TSA5511, and LCD module due to over voltage from the onboard 5v regulator. Many have forgotten to solder the center pin of the 78L05 to the top ground plane of the board for earthing.
5/ Any erratic RF problems are normally due to poor RF connections, or RF problems with the transmitter.
6/ Interference on the picture which looks like faint vertical bars floating across the picture is caused by the 6.4MHz oscillator on the PLL board radiating into the video transmitter board. The problem may only be seen with some video sources depending on the timebase frequency being used in the camera or pattern generator. lead dress of the PLL board and Video Transmitter, and shielding should fix this. Keep the DC tune output lead to the transmitter away from RF. Also try a 10pF ceramic capacitor on the DC tune output of the PLL board to ground, ( across the B-E junction of the BC547 ). Decoupling on the power supply rails with electrolytic capacitors is also worth trying.
7/ Black dot interference or fine horizontal lines on the picture can be radiation from the LCD display modules cable. Lead dress will normally fix this.
8/ To reduce phase noise when multiplying up to 10GHz, try adding a 1nF capacitor from pin 18 to ground on the TSA5511.
Discontinued Product No Longer Supported.
1/ A potential problem could be the soldering of one of the 22uF electrolytic capacitors on the board. It is located at the bottom LHS of the board just above the 100uF Cap. A track runs between the two connections underneath the capacitor. Be careful to align the capacitor when soldering in. Final artwork unfortunately did not fix this problem. Also initial artwork shows the capacitor around the wrong way. The +ve should be on the RHS.
2/ It has been reported that the ERA5 is getting very hot. This was thought to be normal as an older data sheet specifies the bias as 5volts and 80mA. This seems to be a misprint as the ERA Amplifier design guide specifies 4.9volts and 65mA. The 150 and 180 ohm SMD chip resistors should be replaced with 2 x 220ohm in parallel. Also for any other faults in this area, check that there is no copper tracking around the ERA5's mounting hole in the PCB. Use a Multimeter to confirm that there are no shorts.
3/ There has been a report of spurious outputs from the transmitter spaced at +/- 150MHz from the main carrier when tuning across the band. Initially I was not able to duplicate the problem with the prototypes as the board layout is slightly different compared with the final boards. I was sent a EME79 board along with a EME77 PLL board that was erratic in operation. The PLL was having trouble locking due to their being multiple output frequencies being produced by the VCO on the EME79 board. I then disconnected to the PLL and ran the EME79 free running, and found that when tuning the trimpot the output was unstable and was producing multiple spurs each side of the main output. Putting a finger near the tuning lines tended to dampen the problem, and increase the output power. The problem was eventually tracked down the the value of L3, ( 100nH ). I have now changed the value to 1000nH, ( 1uH ) which seems to have fixed the problem. I suspect that the coils self resonant frequency is too high causing it to act more like an oscillator coil than an RF Choke. A replacement coil was posted out to everyone who initially purchased the EME79 Kit.
4/ There has been reports of low 20mW output power from this Kit. It should produce around 50mW, (+17dBm) without the 7dB output attenuator. Tests on 2 current EME79 Transmitters have confirmed the following power outputs at the various points in the transmitter into a microwave power meter. Outputs have been checked against a HP141 Spectrum Analyzer. Output from BFR93A VCO (+10dBm), Output from -10dB pad (0dBm), Output from ERA-5 40mW (+16.5dBm), Output after the -7dB pad 9mW (+9.5dBm).
5/ When using the EME77 UNIPLL on the EME79 Kit there is around 8 to 10dB attenuation through the power splitter. This equates to only 1mW ( 0dBm ) output from the UNIPLL board to drive a power amplifier. The output can be increased by bypassing the 7dB pad on the EME79 board which will then produce around 5mW ( +7dBm ) minimum from the EME77 board which is suitable for a M67715 Mitsubishi PA.
6/ If you are using just the EME79 with the M67715 PA and no EME77 PLL, then the 7dB pad must be changed. The M67715 module only requires 3 to 5mW input for around 2Watts output. Driving it with the full output 10mW, from the EME79 will drive the module too hard,producing up to 4Watts output, but with excessive heat that could damage the module.
7/ For erratic operation of the oscillator across its tuning range, try placing a 1pF chip capacitor across the Collector Emitter junction of the BRF93A transistor. This fixed a problem recently when trying to use the transmitter on 1160MHz for a 5800MHz ATV transmitter. This also increased the transmitters output considerably. Another cause of erratic operation was found to be the connection of the 5.5zMHz subcarrier to the board. The connection should be made underneath the EME79 board, not to the top side.
1/ Kit change after April 2011. BF988 replaced with the Mini-Kits BF998R-M
2/ Major Kit changes 2nd January 2011 due to the Toko MC120 0.8uH coils being obsolete. Changed to a MC120 0.9uH and reduced capacitors across these coils by 2 to 3pF so that they would tune 137MHz. 10pF capacitor across L1 changed to a 6p8, 12pF on L2 changed to 10pF, 15pF across L3 changed to 12pF, 12pF across L4 changed to 10pF.
3/ Problem, Motor boating sound from the speaker. Make sure that the two 0.1uF monolithic capacitors near pin 4 of the MC13135, and the 455KHz demodulator coil are soldered to the top ground-plane of the PC Board. These are used for power supply decoupling. In later Kits just make sure that they have been fitted to the board.
4/ Thanks to Kevin Murphy for the following comments. Just constructed the WESAT Rx the other day. Measured sensitivity was -120 dBm (0.223uV) for 12 dB sinad. The deviation used was 10 kHz. Sinad did reduce at low deviations ~ 3kHz and near 17 kHz, but was reasonably constant from5 to 15 kHz. An important note is that the MC120 coils have two ways of fitting. The cold side (or low end of the winding) is closest to the plastic nipple extending out from bottom end of the can. An article many, many years ago in NZART Break In, showed significant degradation in Q if fitted incorrectly. The input coil, with nipple in the can facing towards the BF988 Mosfet, while the three coils following the RF stage should face towards the VCO coil. The VCO coil should face towards the AFC/Normal Link.
1/ A fault that can occur is no control of the PLL. Check for any solder dags from the 2 x etched strip lines on the top side of the board to the ground plane. This seems to be a manufacturing problem with the PC boards.
2/ Any erratic RF problems are normally due to poor RF connections, or RF problems with the transmitter.
3/ Interference on the picture which looks like faint vertical bars floating across the picture is caused by the 4MHz oscillator on the PLL board radiating into the video transmitter board. The problem may only be seen with some video sources depending on the time base frequency being used in the camera or pattern generator. lead dress of the PLL board and Video Transmitter, and shielding should fix this. Keep the DC tune output lead to the transmitter away from RF. Also try a 1uF electrolytic capacitor on the DC tune output of the PLL board to ground, ( across the B-E junction of the BC547 ). Decoupling on the power supply rails with electrolytic capacitors is also worth trying.
4/ Black dot interference or fine horizontal lines on the picture can be radiation from the the LCD display modules cable. Lead dress will normally fix this.
Software Description Download Synth Readme Document
Software Ver2.10 Only Available By Email. Not For Commercial Use
Discontinued Product No Longer Supported.