VK5EME36 1250MHz FM VIDEO TRANSMITTER KIT

To use the UNIPLL Kit on the EME36 transmitter requires modification to the circuitry.The Circuit diagram of the EME36 Kit with the changes & additions can be found here. A simple Video Amplifier will also have to be added between the pre-emphasis circuit & the varicap diode on the EME36 to increase the video level due to loading by the UNIPLL. A suitable Video Circuit can be found here. The EME36 & 79 Kits have now been replaced by the EME154 Kit that has all these changes & additions to the circuit, allowing either free running or PLL Locked operation. 

VK5EME38 AUDIO / 5.5MHz SUBCARRIER KIT

It has been reported that the frequency of the 5.5MHz oscillator can be unstable, & intermittently jump slightly in frequency. The fault is due to the BB212 varicap diode not having a stable DC bias. The voltage from pin 6 of the TL071 amplifier via the 100Kohm resistor is used to bias the varicap. The BB212 can be more effectively biased by adding a 100Kohm resistor from the +8volt rail to centre cathode junction of the two diodes. The frequency of the 5.5MHz oscillator will now be higher in frequency so you will have to re tune the trimmer capacitor. In some cases a few turns will have to be added to the T37/2 toroid to be able to bring the frequency down enough. 

VK5EME48 2400MHz FM VIDEO TRANSMITTER KIT

The Stripline filter on the EME48 board was initially designed for use on 2415MHz. With a recent shift to 2439MHz for Simplex operation the filter was found to have a 10dB loss, which only allows the transmitter to produce around 5mW output. To shift the filter upwards in frequency, monitor the output power & carefully cut approx 0.5 - 1mm off of each stripline section to increase the output. The downside of this is that the filter will probably not be perfectly flat, & have Ripple across the frequency range but is very usable. 

EME65 500MHz LOCAL OSCILLATOR KIT
  Wednesday 16th January 08

EME65B Construction Web Page Click Here

1/  There has been a report of spurious signals from the output. After building quite a number of these I have only seen the problem when the oscillator is not tuned correctly.  The butler oscillator uses high gain BFR92A transistors that are quite hotter that the originals used in this circuit, & there is a possibility of instability if it is incorrectly tuned.  This was found to be more of a problem with the HY-Q crystals than the low activity Beacon ones. 

2/ Tests by Kevin ZL1UCG on the Capacitor & Coil combination used in the Butler Oscillator. eme65doc The chart has recommendations for the capacitor that should be used to resonate the tuned circuit correctly.

3/ A number of constructors have reported the 10ohm resistor burning up when tuning the 4th trimmer capacitor. The problem seems to be that some of the trimmers may be faulty & short out at some point where the trimmer is set. Check the trimmer with a multimeter if you have found this problem & replace if needed.

4/ If you have low output power & trimmer capacitor TC3 won't tune, then a common problem is one of the two chip capacitors that are soldered on the bottom of the board, many not be soldered on one end, or one is cracked.

5/ Many tune up problems can be traced to the two coils being wound incorrectly. Please refer to the pictures on the Construction Page on how they should look.

EME66 TRANSVERTER SEQUENCER KIT
  Friday 4th May 07

1/  Current Kits are supplied with 3x MJE350 Transistors & 1x TIP32/42.  Only low current transistors are really required for RX power & TX exciter stages.  The higher current TIP32/42 can be used to drive relays or a Power Amplifier. 

2/  A modification has been added to later Kits. The 470ohm base bias resistors for the TIP32/42 Transistors have been changed to 220ohm. This is to increase the base bias current to make them able to switch more current when driving multiple relays or higher current requirements. This was found to be required when driving 2 relays in parallel besides a TX exciter stage. Heatsinking of the TIP32/42 transistors was found to not be required in all transverter prototypes so far. 

3/ Dave VK2TDN has alerted me to a mistake with the circuit diagram on the RX IF Input J3. Refer to the correct circuit here. The PC Board is correct.

4/ After recent testing of the TX Delay circuit is was found to not be slow enough when using the RF sensed RX/TX switching circuit on SSB. This causes the sequencer to go back to RX mode in between words on SSB. The 10uF / 10kohm resistor combination was designed to do this job, but for some unknown reason it no longer works. I am unsure if something may have been changed somewhere else in the circuit, & has changed the operation of this circuit. The fix is to add a 470uF capacitor across the 0V TX connection & GND on the 3 pin header on the board. This adds a good delay time for use with SSB when using the RF sensing circuit.

EME70 2100-2450MHz RECEIVE CONVERTER KIT2

The Stripline filter on the EME70 board was initially designed to have a roll off above 2425MHz to effectively cover 2415MHz & reject microwave oven interference above 2500MHz. With a recent shift to 2439MHz for Simplex operation the filter was found to have a 10dB loss, & degrade the receive noise figure to around 7dB at 2439MHz. A new board EME70B now replaces the original & covers 2250-2550MHz. To shift the filter upwards in frequency carefully cut approx 0.5 - 1mm off of each stripline section. The downside of this is that the filter will probably not be perfectly flat, & have Ripple across the frequency range but is very usable. Other slight changes include the use of a ADE-35 Mixer with better performance & lower cost. 

EME70B 2250-2550MHz RECEIVE CONVERTER KIT

Only one Fault has been reported for this Kit. The Converter was able to tune 2415MHz signals but no signals could be received on 2439MHz. The fault was found to be a faulty 10kohm tuning trimpot. 

EME72/72B 23CM TRANSVERTER KIT

Link to the EME72 Kit Page Here
Link to the Tested results of the Prototypes. Here
Link to a detailed Picture of the constructed Kit Here
Link to faults & modifications Here

EME75 AUDIO / SUBCARRIER KIT
  Monday 28th February 05

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 & 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 & the top of the board in construction. 

4/  Modification to use on 6.5MHz & 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, & For 6.5MHz a 22pF for C1. 

EME77 UNIVERSAL PLL KIT
  Thursday 10th January 02

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, & 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 & 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 & 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, & 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 & Video Transmitter, & 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 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.

EME79 1250MHz VIDEO TRANSMITTER KIT

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 & 80mA.  This seems to be a misprint as the ERA Amplifier design guide specifies 4.9volts & 65mA.  The 150 & 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 the PLL & ran the EME79 free running, & found that when tuning the trimpot the output was unstable & was producing multiple spurs each side of the main output.  Putting a finger near the tuning lines tended to dampen the problem, & 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 poweroutputs 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 & 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.

EME83 925-1800MHz FM ATV RECEIVER KIT

1/ There have been a couple of design problems found with this Kit. Some of the sound & video circuitry has been borrowed from another design in the BATC magazine which has been found to have errors. Some of these were found on the prototype, but there is still a design problem with the sound trap circuitry. The main problem is that the picture has too much high frequency response which makes it look washed out & displays 5.5MHz subcarrier beat pattern. It has been found that the sound trap is ineffective, & that it is actually peaking the 5.5MHz instead of trapping it. It is best at this stage to remove the two 560pF capacitors from the board altogether which fixes the picture quality. To further improve the picture a 1nF capacitor can be fitted from the negative lead of the 470uF capacitor after the de-emphasis network to ground. I will be looking at a modification for this in the near future. The Circuit diagram with the changes can be found here. 

2/ Another problem found was tracking of copper between the tracks underneath the NE592. This was due to the boards being sometimes slightly unetched. The fault is no video output from the board. With current Kits I have been checking the boards before putting them into the bags. 

EME85 AD9850/51 DDS KITS
  Monday 28th July 08

Link to the EME85 Kit Web Page Here
Link to Kit construction notes Here
Link to faults & modifications Here
Link to Software Here

EME94 - 94D 2400MHz TRANSVERTER KIT
  Wednesday 4th June 08

Link to the EME94 Kit Web Page Here
Link to the Tested results of the Prototypes. Here
Link to a detailed Picture of the constructed Kit Here
Link to faults & modifications Here

EME103 PREAMPLIFIER KIT
  Wednesday 4th June 08

Link to the EME103 Kit Web Page Here
Link to the Tested results of the Prototypes. Here
Link to a detailed Picture of the constructed Kit Here
Link to faults & modifications Here

EME107B 10GHz MULTIPLIER KIT
  Monday 14th July 08

Link to the EME107B Kit Web Page Here
Link to the Tested results of the Prototypes. Here
Link to a detailed Picture of the constructed Kit Here
Link to faults & modifications Here

EME117 137MHz WEATHER SATELLITE RECEIVER KIT
  Monday 28th July 08

1/  Problem,  Motor boating sound from the speaker.  Make sure that the two 0.1uF monolithic capacitors near pin 4 of the MC13135, & the 455KHz demodulator coil are soldered to the top groudplane 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.

2/ 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 incorectly. The input coil, with nipple in the can facing towards the BF988 Mosfet, while the 3 coils following the RF stage should face towards the VCO coil. The VCO coil
should face towards the AFC/Normal Link.

EME124 UNIVERSAL PLL KIT
  Monday 7th August 06

1/  A fault that can occur is no control of the PLL.  Check for any solder dags from the 2 x etched striplines 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 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 & Video Transmitter, & 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.

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

EME125 CONTROL KIT
  Monday 23rd December 02

1/  A fault that can occur is no rotary encoder operation.  Make sure that the common terminal on the encoder that goes to DB4 is soldered on both sides of the board.

2/  For any other faults also make sure that connections are soldered on both sides of the board. 

EME139 1960 to 2360MHz Multiplier KIT
  Saturday 5th January 08

1/  A 7809T regulator was added to all Kits after Janaury 2008. The bias resistors to suit the ERA amplifiers were changed to suit.

Image Prototypes of the EME139 KIT3

Tested Performance Data

EME154 1250MHz FM ATV TRANSMITTER KIT
  Thursday 5th June 08

Link to the EME154 Kit Web Page Here
Link to the Tested results of the Prototypes. Here
Link to a detailed Picture of the constructed Kit Here
Link to faults & modifications Here

EME157 VHF PREAMPLIFIER KIT
  Thursday 5th June 08

Link to the EME157 Kit Web Page Here
Link to the Tested results of the Prototypes. Here
Link to a detailed Picture of the constructed Kit Here
Link to faults & modifications Here

WA19 X4 MULTIPLIER KIT

1/  A number of Kits have been sold with the HSMS-2822 version of the 5082-2835 HP Schottky diode.  These are directly replaceable for each other.  Both can be a bit difficult to fit to the board, as it has to be mounted through the hole in the board for earthing.  The lead lengths on both diodes must be kept very short to make them generate good levels of harmonics. 

RA18H1213G PA KIT

1/  A Picture showing how to mount the 1kohm trimpot for the bias can be seen here.
( Old Kits Only )

2/ An Email from Wolfgang, DK1OV and Heinz, DJ2IV on problems & repair of the RA18H1213G modules.

We want to inform you about our project 23-cm PA with the modules, which we got from you. We built two amplifiers, each with two modules in parallel. We mounted the modules onto a 5mm thick piece of copper with the dimensions 100 x 160 mm (about 4 x 6.5 inch) and this onto a big aluminum cooler. This was a lot of work but we did it because you told me to be careful with too much power output due to thermal stress. The amplifier worked perfect first and we got 80 W output at 12,5 V supply. But after a few minutes the power dropped to less than a half, one of the modules failed. The quiescent current was 2 A at the failed module the other module draws 3.5 A. We opened the failed module and found, that the first two FETs didn't get drain-voltage. The supply-line was interrupted near to a blocking-C, in one of the modules the most right one, in the other module in the middle. After we soldered a thin copper wire along the supply-line, the modules worked well again and we had no longer problems until now. We tested the amplifiers for hours with maximum output. The maximum power output is more than 80 W at 12.5 V, it drops to 75 W when the amplifier gets warm and remains constant then. In DATV we get about 20 W linear output with 35 dB intermodulation suppression. We are very satisfied with the result.

SWEEP GENERATOR KIT
  Wednesday 27th June 07

1/  Refer to the EME85 DDS Kit notes above for some possible problems.

2/ Most Faults can be traced to poor solder joints, or solder bridges across connections. Check for correct wiring to the control board & LCD display module.

3/ Low RF output on frequencies lower than 15MHz is normally incorrectly fitted 10nF chip capacitors on the input & output of the MAR6 amplifier. Some constructors have accidentally put 10pF capacitors in place.

4/ Some have reported that when using the Power Head kit on the Sweep Kit that the 0.1dB reading flashes erratically on the LCD & cannot be read. The display will normally change between 0.1dB steps as the meter display accuracy is 0.25dB per step but can be quite easily read. Most problems with this, has been traced to a noisy 12 volt supply to the Sweep Kit. Make sure that you use a well regulated 12 volt Power Supply. The problem only shows when using the DDS RF output & is not a problem with another RF signal generator. I suspect that this is due to the MAR6 on the DDS board generating the noise on the RF due to there being no regulator on its supply.

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