{Collins} Fwd: 30S-1 with negative grid current during standby



---------- Forwarded message ----------
From: Colin Lamb <k7fm@xxxxxxxxxxxx>
Date: Tue, Nov 11, 2014 at 2:22 PM
Subject: Re: {Collins} 30S-1 with negative grid current during standby
To: Lyke That <lykethat@xxxxxxxxx>


Hi Greg:

If someone only used the amp on cw and wanted to use the bias to change to
closer to class C, they may have wanted to adjust the bias during cw and
not worried about ssb.

Have you checked the final tube.  It might have a leaky grid.

73,  Colin  K7FM


Colin, I think you nailed it for me with the leaky grid in the tube.  I
changed out the tube with one out of another amp and the grid current issue
went away!!! Thanks I feel much better!

Now the question is ..... it the tube that has the leaky grid still okay to
use?  Is it near its end of life?  What causes it to leak?  Is there
something that can be done to improve or re-condition
the tube... these amps have been sitting around for quite some time now.

The leaky tube seemed to put out good power with respect to plate current
and drive, pretty similar to the other two tubes.

Is it safe to continue to use this leaky tube?

Thanks Greg WQ0P



This archive was generated by a fusion of Pipermail (Mailman edition) and MHonArc.