GE BA9 Questions.

[WeaveTek]

Saw some earlier posts on the BA9 and am hoping that someone can give me some insite. I am working on a BA9 and have the documentation for the Collins 356E. In the documentation there is a chart for release times that lists FAST and SLOW times in the DUAL position. I didn't see any other reference to FAST and SLOW in the documentation - only a reference to the DUAL vs AVERAGE settings and switch S601. Can anyone explain FAST/SLOW??

    The output level of the unit that I am working on oscillates when the input is between -30 and -50 db. The rate is dependent on the input level and is around 1 to 2 Hz. Faster at higher input levels. The B+ also dips about 10 volts. Seems that something is reducing the B+ which then reduces the output. After the output drops the B+ recovers and the output recovers. Cycle repeats. Any ideas??

Any input or suggestions would be greatly appreciated.

 

[plumsolly]

The 'fast' and 'slow' times refer to the limiter's reaction to sustained sounds above the threshold vs more brief, transient-type sounds above the threshold, when the limiter is in Dual mode. See the Sta-Level manual for an explanation. There is also a note in the RCA 86A manual that floats around which references an NBC modification that I suspect is the inception of the dual time constant idea.

See this thread: http://www.groupdiy.com/index.php?topic=44010.msg549845#msg549845

Best,

Ben

 

[WeaveTek]

Thanks for the information on the dual mode. Still hoping that someone has an idea about the unstable gain.

 

[emrr]

Bad caps?  What's the overall health of the unit?  I'd shotgun the caps before I'd trust any original in a BA9.