A method for achieving ESSB from the Kenwood TS-2000.



Page written by G7VKK.

This modification will allow you to bypass the D.S.P. and produce wider (between 6-7kHz wide maximum) and cleaner TX audio from the Kenwood TS-2000.


I accept no responsibility whatsoever for damage or loss to equipment, persons, places or things as a result of this article or any experimentation that takes place. I accept no responsibility for any interference caused of any description - It is every amateur radio operator's responsibility to test their equipment and transmission and ensure that they are operating safely, responsibly and according to the law applicable in their area.



The Kenwood TS-2000 already produces quite nice audio and with a suitable microphone or other gear can attract unsolicited compliments. However for those who wish to customise their transmit audio signal further it can be rather limiting since the D.S.P does not offer many options for this, and the capacitive strips used in the audio line mean that the audio can sometimes sound a little ‘boxy’.

I discovered this method of creating customised audio several years ago almost completely by accident whilst studying the circuit diagrams.


To allow licensed radio amateurs who are TS-2000 owners to:
  1. Customise their transmit audio signal beyond the capabilities of the D.S.P. for general usage at narrower bandwidths (i.e. < 3kHz).
  2. Experiment with ESSB modes in uncrowded band conditions should they wish to.


Being a musician with keen ears, I also enjoy customising transmit audio. Most of the time I stick to a sensible bandwidth of around 3 kHz maximum as I am conscious of other users on the band. I aim to achieve subtle, intelligable but pleasant to listen to audio. I do from time to time use wider modes such as AM or ESSB if band conditions permits. Whilst I acknowledge that some who are ardently opposed to ESSB, I feel that so long as it is used considerately in uncrowded band conditions, it is perfectly acceptable like many other strands of the hobby. I even wrote to Ofcom asking about this, subsequently receiving a very positive correspondence reinforcing my query. The RSGB now also mentions the use of ESSB in its 'Notes' section of the bandplan. I would encourage all ESSB operators to think about this but I would also expect the same courtesy from other operators in being considerate to the liberty of others in being able to experiment with the hobby too.

More resources can be found at NU9N's article on this subject.

Creating and customising a transmit I.F. signal for the Kenwood TS-2000 using a computer.

This page tells you how to feed your TS-2000 audio into the radio using a computer so as to facilitate a cleaner and wider bandwidth transmission when using SSB. It is the operator's responsibility to make sure that this modification is performed, tested and used properly. I take no responsibility for any loss, damage or interference caused.

The accessory socket at the rear of the TS-2000 allows us to feed audio in after the DSP providing the menu is set up correctly and we use a suitable interface.

We will use a piece of software that is downloadable from the internet called Reaper that contains some excellent features and plugins that will enable us to generate the audio by simply using our sound card and a microphone. I have provided the file that you need to use fully setup via this link:

TS-2000 TX IF G7VKK Reaper File Download

Then by taking the output from our soundcard and using a suitable padding resistor and 1:1 audio transformer we can input it into the accessory socket. You will need to use a separate PTT switch as the front ‘SEND’ and microphone PTT will bypass the audio inputted via the accessory socket.

Step 1.

Set your Kenwood TS-2000 menu settings as follows:

Menu settings 50E (Main / Sub band TNC = Main),

50F (Data Transfer Rate ; External TNC) = 9600bps.

Step 2.

Using an appropriate DIN socket, connect wires to pins 9 (GND via a switch) for PTT and pin 11 for the 'hot' audio. Additionally, I suggest a resistor in series with the audio wire to pad the voltage down and also a 1 to 1 isolation transformer, such as those manufactured by Jensen. This will keep any noise out. You may wish to use decoupling capacitors.

Once you have wired up to the audio, you will need to configure Reaper to play through your sound card. If you load the file shown above, it will set up your audio appropriately to be input directly as the TX IF. You can also set up effects such as equalisation as you would with a rack! Reaper is an excellent piece of software which includes many simple but highly effective plugin effects.

Ensure that the track in Reaper is record armed (red 'R') and that you can see microphone input from your microphone through to Reaper.

Once you have performed these steps, using low power into a dummy load and a suitable monitor receiver (not the TX monitor function which will not work at this stage), listen to the audio produced when transmitting. Click on the ‘FX’ green button on the track and you can adjust the plugins that are inline. You will notice that there are preset filters for different bandwidths.

N.B. there are two different filters for LSB and USB which MUST be selected when you switch modes in addition to any bandwidth filtering, otherwise your audio will not be intelligible! The other filters in the 'FX' window control the bandwidth of your transmission.

Further thoughts

In due course, I am sure that a circuit could be designed to perform the same function. As a matter of fact there are many radios which offer excellent audio tailoring possibilities; in particular the SDR radios.  The TS-950sdx still remains the 'king' in my opinion in terms of flat smooth audio on transmit and receive (including AM) but these are hard to get hold of and are often faulty due to age and poor soldering. The 'ANAN' and other SDRs also provide many possibilities, but I still find that the classic analogue radios seem to sound more transparent both on transmit and receive for some reason. That will be my next project for something to invent. A neo-classical transceiver....