[GreenKeys] ASR 33 question - stop bits?

[Frank Knutzen]

Hi Keith,

No one mentioned the range finder adjustment, so I thought I'd put my two cents in. I was a Marine Corps trained TTY repairman, way back in the day. At the shop we had a test generator which would send RY's with no distortion. The procedure was to move the range finder to one extreme until the copy garbled, record the range number and then go to the other extreme. The correct setting for the range finder was the mid point between the two extremes.

As a MARS operator, that didn't always work as many of the civilian stations we worked had a lot of distortion on their signals. So while they were sending their "quick brown fox" we would often open the machine and adjust the range finder on the fly to get good copy. Had to do both printer and reperf so it was sometimes a real race.

You can check your own transmit signal with an oscilloscope. Send a looped tape with all RY's and look at your signal. The mark and space interval should be a close to identical in duration as possible. The mod 28's have an adjustment screw in the signal contact box. Not sure about the mod 33's. Maybe someone else can help there. Although not as accurate as a real teletype distortion meter, this procedure should easily get you under 10% distortion which should be plenty good for our applications.

Good luck and best of  73's to all,

Frank   KF5EN





On 11/26/2018 1:00 PM, Keith Lueck wrote:
Hi guys -

Brought my ASR 33 out of hibernation lately (hadn't used it in about a year).  It works fine if I manually type on it, but if I try to send it files from my pc, I find I have to use 7 bits, marking parity, and 2 stop bits (7M2) - essentially 3 stop bits; it prints perfectly with these settings.  If I use 7N2, I get occasional errors on long print runs.

Is there something I need to re-lube?  (I don't want to just douse the thing in lube willy nilly - I lubed it pretty well after restoring it).
Should I mess with the range finder?
What else could I check?

Obviously, the problems only occur at full speed, so, a bit difficult to troubleshoot visually.

Thanks,

Keith



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