clh333
Veteran Member
This topic was previously discussed in 2013 at here: http://www.vcfed.org/forum/showthread.php?36372-kaypro-4-keyboard-cable
I have several Kaypros but n-1 keyboard cables so I went to an office supply and bought a telephone receiver cord as a substitute. It worked for one machine (a 10) but not for others (a II and a 4/83). The Kaypro TSM (Aug. 85, p 13-1) mentions that "The impedance of the connecting cable can be a critical factor in proper operation of the computer. Replacement of the standard cable with a phone cord can create malfunctions in signal transmission to the computer. This is because the wire in phone cords is too small: therefore, the impedance over the total length of the card can be too high for reliable operation."
I measured my replacement cable against one of Kaypro's own. Although low in impedence (<10 Ohms) it was an order or two of magnitude higher than Kaypro's (0.1 Ohm). I have also read that the early Kaypros had slightly undernourished power supplies (mine is nominally 60 Watts) and since the cable provides +5V to the keyboard I suppose that even 10 Ohms of resistance might cause unstable operation of the keyboard system.
So much for theory. My question is more practical: Does anyone know where I can get an ultra-low-resistance cable, preferably coiled, preferably in the same length as the Kaypro standard (nominally six feet extended) and preferably terminated with the RJ9 connectors?
Thanks for your replies.
-CH-
I have several Kaypros but n-1 keyboard cables so I went to an office supply and bought a telephone receiver cord as a substitute. It worked for one machine (a 10) but not for others (a II and a 4/83). The Kaypro TSM (Aug. 85, p 13-1) mentions that "The impedance of the connecting cable can be a critical factor in proper operation of the computer. Replacement of the standard cable with a phone cord can create malfunctions in signal transmission to the computer. This is because the wire in phone cords is too small: therefore, the impedance over the total length of the card can be too high for reliable operation."
I measured my replacement cable against one of Kaypro's own. Although low in impedence (<10 Ohms) it was an order or two of magnitude higher than Kaypro's (0.1 Ohm). I have also read that the early Kaypros had slightly undernourished power supplies (mine is nominally 60 Watts) and since the cable provides +5V to the keyboard I suppose that even 10 Ohms of resistance might cause unstable operation of the keyboard system.
So much for theory. My question is more practical: Does anyone know where I can get an ultra-low-resistance cable, preferably coiled, preferably in the same length as the Kaypro standard (nominally six feet extended) and preferably terminated with the RJ9 connectors?
Thanks for your replies.
-CH-