REMOTE CONTROL OF YOUR TRANSCEIVER


There is several reason to take a remote control of a transceiver .As  it is well known transceiver and all the strings attached are not considered as very scenic by most of people especially spouse  and therefore most of the Oms are obliged to operate from hidden location like underneath the roof  , in cellar.... some being fortunate enough to have big house or appartment operating from a dedicated place well situated .It is sure that the Om in his  shack beneath th roof is not bothered by the surroundings  but it is not a nice place especially in winter when it is freezing outside  .Since a few years   PC (personnal computer ) is not considered as bad as transceiver in a living room and is  becoming   a normal piece of household goods . Thanks to the widespread use of CAT plug (Computer Aided Transceiver )  on modern transceiver it becomes easy to operate your transceiver from the living room .Some commercial devices using wireless connections are even available to do the job  .We will describe a set up relying on  standard phone line to link your PC to your beloved transceiver , very easy to build and not expensive at all .With it you will have full control of your transceiver using freewares  available over the internet network .What you need is a CAT interface on your transceiver  and a PC running WIN 98 or newer operating system .


GENERAL DESCRIPTION


You will need to build 2 boxes  , one on the PC side and one on the transceiver side .The PC control  box contains a microphone amplifier   , a head phone attenuator and a 6 to 9v power pack which feeds the 2 boxes .The PC box is linked to the RS232 output of the PC using a standard DB9 connector .Only RX, TX and GROUND are used . The box is connected to the TRANSCEIVER BOX with  standard phone line .This type of line is widely used  and can be found easily for a very reasonnable price .It consists of 8 wires , each having a different color ..Not all the 8 wires are in fact used .Only 6 of them are in operation  , the two remainings can be used for other purposes depending on your particular needs .The microphone amplifier is based on a LM386  integrated circuit The signal taken from the microphone is amplified and send over the phone line  to become attenuated in the transceiver control box so as to reduce QRM taken by the phone line .The length of the phone line can be anywhere between few meters up to 40 meters (no tests being made for longer length)


Full view of the general overview

The transceiver control box contains a RS232/TTL converter  so as to adapt the signal accepted by the computer (RS232 level ) to the TTL level accepted by most transceiver CAT interface .The conversion is done using a MAX233 circuit from MAXIM Inc .One of the advantage of this one is that it does not required any condensators  but other type can be also used (like the well known  MAX 232)  if your have them in stock .All theses circuits need a 5 volts regulated supply  which is obtained by a 7805 regulator .In the transceiver control box  2 isolation transformers (T1 and T2 ) are also used .T1 received the amplified audio signal coming from the remote microphone ..The signal is attenuated  with a 10 k potentiometer before being send to the microphone connector of your transceiver .using a shielded cable . T2  receives the audio signal coming out of the transceiver and send it over the phone line to the PC CONTROL BOX .T1  and T2 are of the same type , they are phone isolation transformers (600 ohm  impedance ) .The total consumption  is around 20 milliamps  .



HOW TO BUILD

This project is quite straight forward and does not requided special tools or expertise  .You will have to grab the various connectors depending on your transceiver and the different components listed in the parts listing The transceiver box must be put into a metal box to prevent any HF coming into the mic line of the transceiver .The cables between the transceiver box and the transceiver must be shileded for the same reason  .Be sure not to make any mistake in wiring the differents modules  and also   the cat connector .Just in case double check that your cat system is compatible with the TTL level generated by this device


.schematic of microphone amplifier    schematic of rs232<>TTL converter

PARTS  LISTING * phone line  lenght as required * LM 386 (audio amplifier) * 1 Kohm ajustable potentiometer * 4 k ohm potentiometer *  1 microfarad condensator (x2) * 10 microfarad condensator * 0.1 microfarad condensator (x2) * 7805 regulator  (78L05 also possible) * battery pack giving anywhere between 6 to 9 volts * isolation transformer  (x2) * MAX  233  (rs232/ttl translator)

HOW TO OPERATE

The fist thing is to test the whole set up with the phone line cable having more or less  its final length and   by  putting the computer , the 2 control boxes and the transceiver in the same room. Check that ou are able to hear the sound coming from the transceiver and that le signal coming from the microphone is able to drive at the normal level the transceiver.Adjust the potentiometers accordingly  .Download , if dont have it the HAM RADIO DE LUXE , a freeware  from  HB9DRV   which is able to control most of the modern transceiver throuh the CAT interface .Plug the DB9 connector into the PC and the male cat connector in the transceiver .By  running HAM RADIO DE LUXE  you should be able to take full control of your transceiver .The only problem if you dont have an automatic antenna tuner  will be that you will have to go in the shack to tune the antenna in case you switch to another band . Wth this set up you can operate not only on SSB but also  the various digital mode by connecting the microphone line and the HP line of the PC control box to the sound cart of the PC .In this cas you will have to use the various package like DIGIPAN ,MMTTY .....If you have special needs  that you do not find in the various packages available on the internet  , it will be easy for you ,assuming you master a computing language like Visual Basic , to make your own programm that fit exactly  your needs  .As an example of what can be done  you can download a very simple package allowing you to take full control  of the transceiver .(download the example in visual basic) .The example is for a FT 840 and as you know cat commands are not the same for the various transceiver Thererfore you will have to change the code  that are generally indicated within the documentation of your transceiver .Ok it does not have the nice look of HAM RADIO DE LUXE but it is opened to all your needs .




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