HP 7907 read preamp question

Jon Elson elson at pico-systems.com
Mon Oct 23 20:25:33 CDT 2017

On 10/21/2017 12:43 AM, Chuck Guzis via cctalk wrote:
> No, it turns out the answer is to set the preamp gain at 
> spec. It appears to do nothing but create more problems if 
> turned up higher than that. It was worth a try. --Chuck 
Well, then, now you have your answer!  From working with 
tapes and drives a long time ago, I seem to recall that 
unless you had print through, the difference between a 1 and 
a 0 was quite large, so there really was no need to fine 
tune the gain or slicer levels.  If you had varying signal 
amplitudes, it was more likely dirt on the heads, really bad 
tape weave or something crazy like that, and mechanical, and 
not variation in the tape signal itself.

We tried some extended-length tapes that were about half the 
thickness, and quickly saw nasty print through trouble, and 
got rid of all of it.  (This was likely at 1600 BPI, might 
have even been worse at 800 BPI.)


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