[Johnson] Ranger 1 Question/Problem
Jim Brannigan
jbrannig at optonline.net
Thu Apr 7 18:36:54 EDT 2005
To Glen and Scott,
I took a look at the Ranger and there are soooo many screws in the VFO
shield.
It is reasonable to check the VFO stability (lazy factor) before I make a
decision.
I will let you know.
Jim
> Since the people who have been making frequency
> stability measurements of the Ranger with the resistor
> both inside and outside the compartment have found
> that the VFO is definitely more stable inside the
> compartment I would put a similar value resistor, but
> in a higher wattage, inside the compartment. This is
> for temperature stability.
>
> Glen, K9STH
>
>
> --- Jim Brannigan <jbrannig at optonline.net> wrote:
> > The conventional wisdom ( in all the on line
> > literature) is to move the
> > Ranger VFO VR dropping resistor to the OUTSIDE of
> > the VFO box.
> > I have done so, but the Ranger is still on the bench
> > so a change is not a
> > big deal...
> >
> > What is the new "conventional wisdom"?
> >
> > Jim
> >
> >
> > > Makes sense to me, Glen. I don't relocate them
> > anyway, I just change out
> > the
> > > original carbon unit with a 7.5 watt 18K Dale
> > wirewound, and that seems to
> > > work just fine. Doesn't change the wattage inside
> > the VFO cage, just
> > spreads
> > > it out a little. Ha. Hope folks don't get the idea
> > they don't have to do
> > > anything about R3, though. It will fail for
> > certain someday, and it's
> > > failure mode will invariably be decreasing R, with
> > a resultant increase in
> > > load on VR tube, and concurrent increase in I as
> > the poor overworked VR
> > tube
> > > works it's little guts out trying to keep up,
> > which of course increases
> > the
> > > current through R3 again, which increases the
> > heat, which increases rate
> > of
> > > R decrease, ad infinitum. A classic vicious
> > circle, and the eventual
> > result
> > > is not pretty, as documented by some photos
> > floating around the web.
> >
> > Johnson mailing list
> > Home:
> > http://mailman.qth.net/mailman/listinfo/johnson
> > Help: http://mailman.qth.net/mmfaq.html
> > Post: mailto:Johnson at mailman.qth.net
> >
>
> Glen, K9STH
>
> Web sites
>
> http://home.comcast.net/~k9sth
> http://home.comcast.net/~zcomco
>
> __________________________________________________
> Do You Yahoo!?
> Tired of spam? Yahoo! Mail has the best spam protection around
> http://mail.yahoo.com
More information about the Johnson
mailing list