PIX serial port problems?

Is anybody else having issues with the serial console on newly purchased
PIX 515 and 525 firewalls?

Today I was hooking up two new PIX firewalls as a failover pair, I did the
initial configuration at my desk with the blue molded "roll cable",
no problems.

I move the PIXen to production with console going to a Portmaster (PM-25)
for both firewalls --  One firewall console worked, the other was dead.
Switch the console cables, and the dead firewall stays dead.

So my next step is to put inline one of those passive Radio Shack
"RS-232 Mini-tester" boxes.  All the correct LEDs are brightly lit,
and when I test the console, it works...  until I take out the mini-tester.

I unpacked another brand-new PIX 525, and have the same problem.

The console only works with the mini-tester inline, for this one firewall!?!
I know I have DTE/DCE correct, so at the moment my best guess is that the
RS-232 signal from this one PIX is running hot, such that the portmaster
cannot handle it?

Put in the mini-tester and it pulls down  the signal voltage, and all is well,
assuming I want to dedicate a fifteen dollar mini-test to each PIX and have
the cabinets resemble a low-budget xmas display.

Has anybody seen anything like this before with a PIX?
With a portmaster?


Thanks,

Kevin Kadow

(P.S. Would any of the sub-$300 portable or PC oscilloscopes be suitable
for debugging RS-232?)