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Note for pk88
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Internet Message Format
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1993-08-03
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2KB
From: n2oqn%w3ya@gw.af2j.ampr.org
Subject: The PK-88 Mod
Orig: 18-Mar-92 23:41 @:N2OQN #:347
The following is a description of the problem with using the PK-88
without the Mod and the appropriate fix:
As I'm sure you well know, Hardware Flow Control is an integral part
of a successful Packet Program. This is where the problem lies in using
the PK-88 as is with programs like Net/Mac. Specifically, the problem lies
in the fact that, although the PK knows how to utilize Hardware Flow Control
(HFC), it is not set up correctly for the standard interface cables.
The NET/Mac software is trying to talk to the PK, in terms of HFC, and
the PK isn't looking in the right place (or even better, not on the right
pin. HiHi) The fix can be done in two different ways, one which involves
the modification of the cable, or the other one which requires the modifi-
cation of the TNC itself.
Logic told me that if I ever had to buy a new cable, there would be no
problem except for having to modify it also, but... If I ever had to buy a
new TNC, I'd be in deep trouble. HiHi. This is why I made the mod to the
TNC, NOT the cable. I don't know how to do the mod to the cable, but I do
know how to do the mod to the TNC, and it goes as follows:
1) Disconnect power (Duh!) and remove the top cover.
2) Locate the DB25 Connector toward the back of the unit, where you will
note that this is the cable going to the computer. RS232. It's a big
25 Pin connector.
3) Just forward of that connector, on the PC Board, you will see 6
resistors, numbered R4 - R9.
4) Note that this step takes place on the connector side. i.e. do the
modification to the leads of the resistors FACING the connector.
You must 'jump' resistors R5 and R7 together, ON THE CONNECTOR SIDE
OF THE BOARD.
5) Replace the top cover. (Duh!)
6) Have Fun!!!
* Note: Not all cables are capable of the hardware flow control needed.
In this case, you must find a cable that is (some of them simply
don't).
Connect all of the pins required on the back of the mac to the
DB25 as necessary. (The Apple Printer cable, as it is called,
does NOT work properly, modification or not. Go to an aftermarket
cable.)
Well, That's it. Hope this helps you out, and happy soldering. HiHi
73, Danny (N2OQN @ W3YA.PA.USA.NOAM)
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