[RTTY] Help with HD-3030

[DJ3IW Goetz]

Hello RTTY friends.

My new computer does not have ISA slots so I had to retire the
HAL PCI-3000 board. As I want FSK RTTY and a RTTY scope, I put
my Heath HD-3030 TU back into my system. I've last used it about
10-12 years ago. After some fiddling with the connectors and
a CAREFUL realignment of the 2125 Hz and 2295 Hz filter boards
to exactely these frequencies it is working. Using Writelog/Rttyrite
I can receive and transmit FSK Baudot and I have a RTTY scope.
Now the peculiarity: With the HAL PCI-3000 a properly tuned 170Hz shift
RTTY signal gave two ellipses exactely perpendicular to each other.
Any slant in this display indicated either a larger or smaller shift,
i.e. 200 Hz for example or improper tuning (by me). The HD-3030 however
displays the ellipses for a properly tuned 170Hz shifted signal with quite
an amount of slant. The ellipse for the space signal is almost where its
supposed to be, vertical. The mark ellipse is slanted by about 30 degrees
to the horizontal. With the PCI-3000 this correspond to a 200Hz shift signal.
Proper tuning and 170Hz shift were verified with MMTTY and its software scope.
The HD-3030 documentation refers to a phase shift network in the
input circuit of the 2295Hz board. Caps and resistors are of fixed value.
Due to the long time since I last used the HD-3030 I do not remember any
more if this kind of scope display is/was normal...
Do the old hands know of a way to correct/change this behaviour?

73 de Goetz
dj3iw@t-online.de