[Heathkit] SB-610 focus problem?

[manualman at juno.com]

I added an astigmatism control to my HO-10 back in the "good old days". I
think the simple circuit came out of one of CQ's Ham Clinic articles.
Don't recall the issue but probably late 60's or early 70's.

Pete, wa2cwa

On Sun, 27 Oct 2013 21:11:51 -0700 Ian Wilson <ianmwilson73 at gmail.com>
writes:
> Some of the Heathkit scopes have a separate Astigmatism trimpot
> in the HV divider chain. The SB-610 doesn't. I would guess that 
> some
> CRTs are OK without and some need the extra balancing.
> 
> The deflection circuits are single-ended so there's always going to
> be some compromise, I think.
> 
> 73, ian K3IMW
> 
> 
> 
> On Sun, Oct 27, 2013 at 6:54 PM, Alexander N. Gerli 
> <ac1wye at gmail.com>wrote:
> 
> > *Hi, folks,
> >
> > *
> > *I've been using my '610 for a long time and it's always been 
> reliable,
> > especially after I recapped it.
> >
> > *
> > *I'm wondering about something. For those who run these, have you 
> ever
> > noticed how the trace line can be focused real sharp in the center 
> and it
> > gets out of focus at the edges? Not by a whole lot, but it's 
> noticeable.
> >
> > *
> > *I also have a HO-10 I've rebuilt and I use that on my bench with 
> my dummy
> > load for testing. The horizontal trace on that is clean all the 
> way across
> > once the focus is set.
> >
> > *
> > *Is there something I need to get into and check on the '610, 
> maybe an
> > out-of-spec resistor(s) or something else in the Focus circuit? 
> Anybody
> > have a thought on this?
> >
> > *
> > Thanks es 73,   Sandy AC1Y
> >
> >
> > Alexander N. Gerli, Sr.
> > 548 Allred Mill Road
> > Mount Airy, NC 27030-2202