Pertec Interface Cable Length

[Douglas Taylor]

On 8/11/2019 7:01 PM, Jon Elson via cctech wrote:
> On 08/11/2019 11:11 AM, W2HX via cctech wrote:
>> I seem to remember they were ribbon cables
>> with each odd/even pair twisted which probably meant one
>> active and one ground twisted together.
>>
>> Or differential pairs.
>>
>>
> No, both Pertec unformatted and Pertec formatted interfaces were TTL 
> single-ended.
>
> Jon

I just looked at the TC02 and the Qualstar, there are termination 
resistor packs on each.  The Qualstar has a bunch of 74LS240 IC's near 
the J1 and J2 pertec interface cables.  The TC02 has a bunch of 74LS374 
chips near the J1 and J2 connectors.

This is where the electrical engineer could help.  How do you determine 
how long a cable the 74LS240 can drive?

Doug