[R-390] I need R-1283/GRC information

[Jim Green]

A bit off topic but I couldn't find a R-1283 site.

I have a R-1283/GRC 30 through 300 Mc Receiver. I have no manual. If  
anyone out there has a Manual I would be willing to pay a reasonable  
fee for a copy. The receiver powers up and I am able to tune in  
signals. There is a slight audible hum when using an exterior antenna  
but (strangely) no hum when using a short piece if wire clipped to  
the Ant. Input. I am able to listen to the receiver through  
headphones via the 1/4 inch jack on the front panel. I have it rack  
mounted with my R-2368 receiver and a audio amplifier that drives a 4  
ohm speaker. I would like to connect the R-2368 to the same  
amplifier. However, I don't know quite how to do it. A manual would  
be very helpful but short of that perhaps someone could give me some  
direction. On the rear of the R-1283 I find the following Jacks:

Antenna 1 & Antenna 2, Type N with an Antenna selector switch below  
them. I'm using Antenna 1, but Antenna 2 works fine to.
IF Output Test, Type BNC (I expect this is the 455 IF output) No  
explanation required
ATI J3 LO Output, Type BNC I have no idea what this is for.
VID Output J2, Type BNC I assume this is for video output for TV  
signals or Weather Satellites. But I'm not sure.
PIU Output J1, Type BNC I have no ides what this is for.
There is a 15 contact terminal strip Labeled TB1 I suspect my audio  
output comes off this terminal strip. Can anyone provide a pinout for  
this?
There are 6 each test point connecters labeled:
AGC
Video
Grd
VDC -12, +12, +110

There is also  3 position Toggle switch labeled COR delay with  
settings of 3 SEC. 0 SEC & 10 SEC. What does this do?

If anyone has a manual or knows where I can get one........

Cheers!

Jim