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TS-64 Information

Compiled by Mike Morris WA6ILQ

The TS-64 can not only send "Reverse Burst" (160ms of 180 degrees phase shifted tone after the keying line is no longer active), but it will also stop decoding virtually instantly (specs say 160ms) on a detected phase change, otherwise known as "Reverse Burst", "Squelch Tail Elimination"... etc., if your encoder at the sending end does it (normally it's rated to stay open for 350ms on loss of tone). Unfortunately, it only has the 180-degree phase shift, because that is really easy to do. It cannot encode or decode a 120-degree phase shift, so that means it is fairly useless with late model Motorola radios (and a few other radio brands that use 120 degree shifts). On the other hand, another nice feature that shows that the designer did a lot of thought is the encode tone output waveform starts and stops at zero crossing thereby preventing any "click" when turning the tone on and off.

If your second-hand TS-64 doesn't seem to follow the standard chart in the area of the 32 standard tones, don't panic. There were an unknown quantity of early units made with the tone table rearranged to allow for a rotary switch to ground one of the six tone select lines to select six specific (customer requested) tones. If you have a perfectly operating second-hand unit except that the tone table is arranged differently you may have one of those specials.

Note: The TS32 was supplied with colored wires that could be plugged onto any pin, therefore it was useless to give hookup instructions based on wire color. The TS64 has consistent wire colors so it's worth presenting this list:

  1. Red is + DC power in.
  2. Black is ground.
  3. The green wire is the AUDIO INPUT. Hook this to the receiver discriminator.
  4. Ground the violet HANGUP wire or it will stay in "pass the audio" mode all the time (i.e. it will never decode). This is the biggest single error in connecting on the TS64 - if it is acting like it's dead right out of the box (i.e. not decoding) make sure that the hang-up lead (the purple wire) is grounded.
  5. Use the white MUTE wire for decode logic output. By default it uses open collector active high signalling (i.e. this signal will go high for decode), but it needs a resistor from this pin to a voltage source to do it. If you need active low install jumper JP7 to cause the signal to go to ground on decode.
  6. The yellow wire is the ENCODE OUT. This is the audio that is run to the transmitter modulator.
  7. The orange wire is the PTT input. Ground this to switch the tone encoder on. When ground is removed the encoder phase is shifted, and the encoder stops when the 160ms is over.
  8. The gray wire is the PTT OUT. This signal goes low when the orange wire is grounded and stays low for the duration of the grounded input plus the reverse burst timing. In normal mobile radio use the PTT lead from the microphone would be disconnected from the radio and be connected to the orange wire, and the grey wire would be connected to the point in the radio where the microphone PTT lead was.
  9. The blue wire is the FILTERED AUDIO OUT. The path from the green wire (in) and the blue wire (out) has a high pass / low cut audio filter in line, designed to remove the subaudible tone from the user audio. This is an installers choice - you can feed the blue wire back into the receive audio connection. This type of radio surgery is very radio dependent and cannot be covered here. Many radios have a high pass filter in them from the factory and in that case you can simply tape off the blue wire and ignore it.

There is no really easy way to eliminate the reverse burst (and why would you want to?). If you absolutely have to, just ground the PTT IN Lead (the orange wire) then switch the encode tone output (the yellow) wire, perhaps with a set of reed relay contacts in series with the audio, or a FET-based audio pinch-off switch.

This page split from the main index page 16-Nov-2011.

This web page, this web site, the information presented in and on its pages and in these modifications and conversions is © Copyrighted 1995 and (date of last update) by Kevin Custer W3KKC and multiple originating authors. All Rights Reserved, including that of paper and web publication elsewhere.