{Collins} Re: 70K-2 PTO drift



Way back, we did some testing on dielectric coefficient of materials as a
function of their molecular structure. We did found that certain materials
among them micas and some other composites do change their molecular
structure over time, and hence their dielectric coefficient ( see "cold flow
of solid materials" ).Causing flow of electrical current through them, will
sometimes bring them back to where they were before, if  not changed  beyond
a certain maximums.(plastic zone) These tests were mostly done on
capacitors,and some other electronic components, to try and explain just
that. changes in their values or their stability over time. Now, I don't
know of which dielectrics exactly the PTO caps are made of , but it pretty
much like what we have concluded.
But I might be wrong altogether.
Ira
CE3AM........4X4SW
----- Original Message -----
From: "Bob Stewart" <bob@xxxxxxxxxx>
To: "wglevy" <levyfiles@xxxxxxx>; <collins@xxxxxxxxxxxxx>
Sent: Friday, February 04, 2005 7:28 PM
Subject: {Collins} Re: 70K-2 PTO drift


> Bill and others interested,
>
> Another thing I've noticed is that a measly 10 seconds
> with the -5 in remote mode causes almost 200Hz of
> drift of the main PTO.  In remote mode, power is
> removed from the plate and screen of the PTO's 6AU6,
> making it all due to a change in inter-electrode
> capacitance.  It quickly comes back "in", though after
> putting the -5 back in internal mode.
>
> Bob - AE6RV
>
> --- wglevy <levyfiles@xxxxxxx> wrote:
>
> > I think you are right. Its a good thing.
> > What I didn't think about is tubes going sour.
> > Happens so rarely over the
> > years.
> > But when you use a radio thats stable and it keeps
> > getting worse with drift
> > then obviously its tube time!
> >
> > ----- Original Message -----
> > From: "Bob Stewart" <bob@xxxxxxxxxx>
> > To: <levyfiles@xxxxxxx>; <collins@xxxxxxxxxxxxx>
> > Sent: Friday, February 04, 2005 2:17 PM
> > Subject: Re: {Collins} Re: 70K-2 PTO drift
> >
> >
> > > Thanks Bill,
> > >
> > > For some reason, I hadn't even considered the tube
> > > inter-electrode capacitances as part of the drift
> > > equation.  But, changing that tube out moved the
> > dial
> > > about 5 kc to the left.  I need to check this out
> > a
> > > little better, but considering that the dial had
> > > drifted to the right over 5kc in the past 6
> > months,
> > > I'd have to think it's a good thing.
> > >
> > > Bob
>
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Nets: Tues: 3.805 Mc-2000 Central / Thur: 3.875 Mc-2000 Central
Fri: 3.895 Mc-2000 Pacific / Sun: 14.263 Mc-2000 UTC
1st Wed (of the month) AM Net 3.880 Mc-2000 local (ET, CT, MT, PT)
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