Hi Bruce: When you say that the telex machines used a "high-voltage DC, 60mA current loop," is that implying a 120V loop as in standard TTYs? The reason I ask is that the "private-wire" current loop for an M32/33 is a max of something like 45 volts on the loop supply. I presume then, that the telex interface box was designed for the HV, 60-mil telex loop, and then in turn drove the internal 20-mil input to the selector-magnet-driver card of the M32. Was this telex interface box in the M32 stand? I had not heard of later M32s having Telex Line Adapters for FSK modem application. How can you identify which interface an M32 has? Was there a different dialer CCU, like the one with six pushbuttons used on the twx 33s? I have some additional telex info from other folks added below. ps: Bruce, did you see the post about all those TTY machines for free in Seattle? Lots of good stuff headed for the dump. gil ------------------------------------------------- More telex info from George Hutchison: Using a Teletype Corporation equipped telex machine on RTTY is relatively easy. You need a loop supply with a current limiting resistor (2K or so wirewound pot) a double-pole double-throw switch, and the telex machine. Connect the DPDT switch in the standard manner for reversing polarity. Feed the loop supply (Such as one would find in a 28 LESU) through the pot to the center terminals of the switch. Wire the reversing terminals of the switch to the telex machine input cable/terminals. If you plug the telex machine into 110 VAC, with the loop supply de-energized, it will run open. Some folks tweek the dial on the telex a bit to get the machine to lock up, but this is not necessary. Energize the loop supply. Depending upon the position of the DPDT Switch, the machine will either stop running open, remain on and be ready to type uponst, or will shutdown and the motor will stop. Flipping the switch will result in the opposite condition to occur. With the machine energized and the loop locked, set the loop current for 60 ma. When the machine is on and ready to type, it will key the loop that is coming from the loop supply. From there it is easy to use it to key another machine, a transmitter, or what have you. When the machine is in the off condition, motor shutdown, etc, depressing the "LOCAL" button on the telex will cause it to come to life so you can type locally. I have an ST-6 that I removed the 110VAC that goes through the motor control relay, and set it up with the reversing arrangement as described. Most ST-6 motor control relays were DPDT. The loop current from the ST-6 goes through the motor control/now reversing relay, so when the ST-6 says turn on the motor, the loop current flips polarity and turns on the telex machine. Such a deal. Thought some of you might like this bit of info. 73, George, W7KSJ ------------------------------------------------- More telex info from Don Robert House: I have always just used the loop rather than tapping into the SMD circuitry. I set a loop supply of 120-130 vdc to 62.5 milliamps with two machines wired in series into the loop. The machines usually have a mounting cord on them for this purpose. The M32, if it is a former Telex, it uses the ITA2 version of Baudot code. It is a 7.00 unit code with 1 start bit and 1 stop bit, which is 50 baud and 67 words per minute. ------------------------------------------------- More telex info from Jim Haynes: There are two Telex interfaces to the M32. One is neutral, and the other is a polar adapter that plugs into the neutral one. Look in the Western Union Technical Review CD ROM; I think it's all documented in there. And yes, it's 50 baud, 7.5 unit code. ------------------------------------------------- More telex info from Wayne LeTourneau: Most Telex's are 66 WPM, I have 60WPM gears in mine and I connect the local loop to terminals 8 & 9 in the rear. Local loop set at 60ma and not to exceed 100 VDC. It copies fine, I'M using a Flesher 170 tu. It also has automatic caridge return and automatic line feed, so can copy those RTTY stations that are using computers and don't have enough sense to send a LF and CR at the right time. I cannot get mine to talk to itself yet, have not figured out how to get the keyboard in series with the printer. Actually, the selector Magnets on thease draw close to 500ma, so you have to use the driver card, which is where terminals 8 & 9 end up. Wayne WB0CTE ------------------------------------------------- division (when they still had one), fixing those things. required a dedicated hookup to a specially-equipped Western Union central office. The normal interface was high-voltage DC, 60mA current loop. In the case of longer-than-typical cable pair length, a polar adapter was employed to create a differential DC interface. used FSK, as you've already guessed. I don't recall the frequencies involved exactly, but 2200/2000Hz Mark/Space wants to stick in my head for some reason. and some other of the more industrialized countries, replaced pretty much by the Internet and FAXes. The Telex-ready Model 32's ran at around 67WPM (Words per Minute)/50 baud. Amateur Radio RTTY standard calls for 60WPM/45.5 baud. able to, if you wanted, convert it for ham radio use. However, you would need to change the motor gearing to bring the speed down a notch. Finding the necessary gear would be an adventure at best, though I can suggest a couple of possible sources if you want to try this. ;----------------------------------------------------------- ; vaux electronics, inc. 480-354-5556 ; http://www.vauxelectronics.com (fax: 480-354-5558) ;-----------------------------------------------------------