M1 Series Modular Transceiver

M1 Transceiver
Prototype M1 Transceiver
M1 Receiver and TX Driver Stages
M1 Receiver and TX Driver Stages
M1 TX Modulator, PA, Low Pass Filters
M1 TX Modulator PA and Low Pass Filter Stages

Please Note: that all information including pictures on this web page are copyright to Mini-Kits and must not be used on any other web site, or reproduced in any publication.

M1 Description:

Update December 2016. Most of the Kit modules are now completed to fully construct the M1 Transceiver. The only unfinished modules are the Speech Processor and Noise Blanker that are still being designed and prototyped. These have been delayed as its just been too busy here this year as there were other Kits that were more urgent to finish.

Printed Circuit boards and Schematic Diagrams are not available separately as most Kits use a large number of components that are not easily obtainable in small quantities, and have been specifically selected for the optimum performance. Many constructors may think that they can save money using components from other sources, but the full Kit prices are much lower than if you were able to purchase PC boards and try to source the components from various other suppliers. Buying components from unknown sources only adds to the probability that a Kit may not work, or its functionality be affected. For the Highest Performance and Quality, Mini-Kits Only uses first grade high quality components directly from the manufacturer, or large suppliers in the US.

The M1 Series HF Transceiver is a modular design using a number of module boards with 50 ohm RF connections, and a common 16 Pin IDC connector for logic control allowing easy plug and play, and experimentation of the modules. The design is a conventional analogue design using a single conversion 9MHz I/F, very similar to Transceivers that were manufactured in the late 1970's. Many of these Transceivers used narrow pre-selection filters, and quality crystal filters that are only used these days in higher priced Ham Transceivers.

The M1 design brings together the best analogue design techniques that have been used over many years, which have been re-engineered using modern components to improve the performance. Conventional leaded components have mainly been used to make construction easier, and SMD components have only been used where required to either improve performance, or if there was no alternative.

The M1 Receiver produces high quality low distortion audio which does not cause fatigue like lower cost modern transceivers that use DSP filtering. The receiver and transmit audio has that very nice Kenwood sound that is typical of Transceivers that use quality crystal filters. The Transmitter produces a very clean RF output due to extensive filtering and the use of Mitsubishi MosFETs in the PA, and many reports from other stations have commented on the excellent punchy audio that is very easy to listen to.

The M1 Transceiver block diagram shows how the various modules are connected together to construct the receiver, and only a Local Oscillator from 9 to 39MHz is required to feed into the Mixer for tuning the receiver. The functions of the M1 receiver can be easily controlled using analogue switches and simple logic, without the requirement of a micro controller. A dedicated M1 DDS Controller is now available to suit the M1, and can be used with either the AD9850/51 or AD9951/54 DDS chips for stable frequency and easy logic control of the M1 module functions.

Many of the modules shown in the M1 Transceiver block have a dual function, and also also used in the transmitter, these include the EME201, 202, 203, 205 and 207 Modules. The EME208 Transmit Modulator, EME210 16W amplifier, and the EME209 Low Pass Filter Kits are now completed and available. There could be a number of other modules that maybe available later on including, an optional receiver protection module that could also incorporate a SWR circuit, and there are plans to also do a noise blanker, and RF speech processor module.

For more information on each module, please refer to the Modules specific web page links at the top of this page.

What Components Are Required:

The M1 Transceiver was not designed to be sold as a complete Kit, so we have produced an Excel Spread Sheet that can now be downloaded to help calculate what you might require including the costs to construct your own version of the M1 Transceiver. Due to limited hardware manufacturing in Australia, there are no plans to supply a complete enclosure or front panel assembly. The cost to produce anything like this in Australia is just not viable.

The Basic Module Kits include the IDC header connectors but do not include the 16 way 1.27mm ribbon cable, RF connectors, cable, or hardware. It is recommended that SMA connectors are used on the modules to make easy interconnection between the various boards, however RG316 or similar cable cable be directly soldered between the boards to keep costs lower. If you want to construct a simple analogue design without the M1 logic and micro controller, then you can use simple logic control using switches, and a 9 to 39MHz VFO oscillator for tuning.

The picture below shows the modules that are currently available to construct the complete M1 Transceiver that covers all the HF Amateur Radio bands, ( Excluding the 30M Band ) from the BC Band to 30MHz. The modular design allows the constructor to only purchase filters for bands that are required to save on costs. A number of the modules shown have a dual function and are also used in the transmitter, and the addition of a SSB/CW modulator, RF power amplifier and low pass filter is all that is required to transmit on a single band.

M1 Receiver and TX Driver Stages
Prototype M1 Receiver and TX Driver Stages
M1 Receiver and TX Driver Stages
Prototype M1 TX Modulator, 16Watt PA and Low Pass Filters

M1 DDS Logic and Controller:

A complete M1 DDS Controller solution is now available, and will allow full control of the M1 modules functions and power switching requirements. The HF-DDS software has been modified to suit the M1 Transceiver functions, and can be used with either the AD9850/51 or AD9954 DDS chips. The M1 DDS controller directly interfaces with the Mini-Kits AD9851 or AD9951/54 DDS Kits, but for the best performance the AD9951-54 is recommended as it produces very low birdies that generally cannot be heard when tuning across quiet bands. The DDS VFO frequency range required by the M1 Transceiver which has a 9MHz IF, is 9 to 39MHz to cover a 0 to 30MHz frequency range. The AD9851 or AD9951/54 DDS board all cover the required frequency range, but due to the AD9851 being only a 10 bit A-D, the low level birdies generated by the DDS can be very weakly heard on the higher HF bands when atmospheric noise is low. So it is suggested that for higher performance applications that the AD9951/54 14 bit DDS boards be used, as the strongest birdies from the 14 bit chips are more than 60db down. For use on the lower frequency bands under 10MHz, the AD9851 board has been proven to work very well and birdies are mostly under the noise floor. The AD9850/51 however does still produce a couple strong birdies on spot frequencies that could be annoying if they are on your favorite frequency.

M1 PIC Controller
Prototype M1 PIC Controller Kit

Mounting Into An Enclosure:

1/ Unfortunately due to a very high work load I am still attempting to put the transceiver into a Hammond 1401P enclosure. I understand that there are many constructors that are waiting to see how the complete hardware all comes together and to see a final product. An Excel calculator can now be downloaded to guide constructors on what might be required including the costs.

It is important to layout the modules logically with regards to the distances required between the modules and other hardware like the S-meter and potentiometers etc that might require clearance inside the enclosure. You also need to take into account with keeping any high gain RF stages away from lower level RF stages and also keeping the micro-controller and DDS away from the receiver. As the pictures shop below, the mounting of the boards into the enclosure has finally started. Most of the receiver circuitry has been mounted onto the top of an aluminium chassis giving plenty of clearance around the modules for cable wiring.

M1 16 Watt PA Mounting V1
Mounting of the EME210 16W PA to the Enclosure
M1 16 Watt PA Mounting V2
Mounting of the EME210 16W PA to the Enclosure
M1 Preselect Filters V1
Mounting of the EME207 Preselector filters
M1 Preselect Filters V2
Mounting of the EME207 Preselector Filters
M1 Mixer and RF Amplifier V1
Mounting of the EME201 Amplifier and EME202 Mixer
M1 Mixer and RF Amplifier V2
Mounting of the EME201 Amplifier and EME202 Mixer
M1 BFO Demodulator
Mounting of the EME205 9MHz BFO Demodulator
M1 Audio Amplifier
Mounting of the EME206 Audio Amplifier
M1 9MHz AGC Amplifier
Mounting of the EME204 9MHz AGC Amplifier
M1 Crystal Filters
Mounting of the EME203 9MHz Crystal Filters
M1 Low Pass Filters V1
Mounting of the EME209 Low Pass Filters
M1 Low Pass Filters V2
Mounting of the EME209 Low Pass Filters
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M1 9MHz Modulator
Mounting of the EME208 9MHz TX Modulator
M1 Logic Circuitry
Mounting of the Micro controller Logic
M1 Chassis Top View
Completed Chassis Top View
M1 Chassis Bottom View
Completed Chassis Bottom View
Front Panel Assembly:

It was decided to try using a thick laminate to create a front panel which can easily be updated at low cost if something needs to be changed. A full size prototype front panel can be downloaded here in PDF format, and below is the prototype panel using 300 x 2 micron laminate on thick paper. The front panel was designed using Autosketch, and I am happy to email a copy of the file if you want to make changes to design your own front panel. The results so far are very pleasing, and allows easy changes to the front panel which are low cost compared to screen printing. The paper was cut out for the LCD display which makes a very nice clear laminate window.

M1 Panel Laminated
M1 Prototype Front Panel
M1 Front Panel Close Up
M1 Front Panel Close Up
M1 Panel S-Meter
S-Meter cutout and laminated window

This picture shows how the transparent window for the S meter looks. The window was cut out of the paper using a sharp scalpel before the paper was laminated. Most holes were punched out using metal hole punches after laminating, and before the laminated sheet was glued to the aluminium panel. Dabs of Bostic Multibond glue was used to stick the laminated sheet.

Panel LCD
LED and LCD Display cutouts and laminated windows

The 3 LED indicators for ATT, PRE and NB were made by punching out the paper before laminating to create bezel windows. The LCD window is made the same as the S-Meter window. The LCD display is fitted using countersunk screws and spacers before the laminated panel is glued to the aluminium panel.

M1 Panel Keypad
Keypad cutout

The picture shows how the keypad fits through the aluminium front panel and the laminated sheet. The laminated sheets uses black surrounds to hide any imperfections with cutting of the aluminium. The large holes are simply cut out using a very sharp scalpel using the aluminium hole as the template.

M1 Panel Completed
The completed front panel ready for assembly

There is quite a lot of work to get to this stage, so any mistakes along the way would mean starting all over again. The whole process of cutting out the paper etc before laminating to get the s-meter and LCD windows, and then punching out holes for the controls etc has to be made in the correct order.

M1 Prototype Front Panel
Dismantling a MU45 1mA Meter

The MU45 meter has been carefully dismantled and the meter scale removed to make a suitable S-Meter scale.

M1 Front Panel Close Up
Artwork from the M0MTJ Website

The S-Meter scale is from the M0MTJ website. It took some time to scale it using Publisher before it was printed using semi gloss vinal on a color laser printer. Click the picture if you want to download a high resolution picture..

M1 Prototype Front Panel
Modified meter with S-Meter scale and 12vdc globe

A 3mm diameter 12vdc axial globe was added to light the meter. Wires were attached before using clear heat shrink to hold them in place. A small hole was drilled in the back of the meter housing to pass the wires.

M1 Front Panel Close Up
The complete S-Meter ready to mount

The completed S-Meter ready to be mounted. It was decided to remove the lower FM discriminator scale as it is not required on the M1 Transceiver.

M1 Panel Construction 37
Assembling the Front Panel Controls

When assembling the front panel, the laminate was found to be very rugged and can easily handle some abuse.

M1 Completed Front
The near completed Front Panel

There was quite a lot of work required to wire up the front panel hardware, but it is a very enjoyable experience seeing it all come together.

Changes and Modifications:

1/ There are a number of changes to some modules that can be found on the module specific web pages to fix mostly minor problems that have been found. There will always be some changes and improvements found over time which is even common with the major manufacturer brands.

2/ There have been changes to the Transceiver Block Diagram to fix mistakes with the RF connections for the Crystal Filter Module, and also additions of the new modules available.

Accidental Faults:

There are many things that can happen when testing boards or when trying to get complex Kits like the M1 working. It can be as simple as slipping with the multimeter or dropping a screw onto a PC board. Listed below are some known failures that I caused myself when playing around with the M1

1/ Oops I shorted out the 16 way ribbon cable that connects to the crystal filter modules. This caused the +12vdc to pin 15 of a number of modules to be not present, including the audio amplifier so there was no sound from the speaker. The fault was tracked down to a burned track on one of the EME186 IDC adaptor boards that I used. The track was open circuit so acted like a fuse and is between pins 16 of each female header. This is probably a good safeguard so make sure that you use some thin wire when repairing tracks.