On 5 Nov, 06:11, "Dave" wrote:
"Stefan Wolfe" wrote in message

...







"Dave" wrote in message
...

"John Doe" wrote in message
om...
If you can't contribute anything positive to this question, then stay
out of it, with your trash!

I have a 10m base loaded mag mount antenna, that I had to put a piece of
felt over the magnet as not to scratch a new vehicle.

When I did this I apparently changed the capacitance between the mag
mount and the roof of the vehicle. Someone suggested that I might want
to replace the felt with either a large balloon or a large prophylactic
as it is thinner and the capacitance would then return to almost where
it should be.

Positive comments only!

Maybe black, electrical tape on the bottom of the mag mount (applied to
that mag mount, of course.) Would be thinner, but I suspect it might
still cause some problems with increased capacitance. Dave

Dave (and John Doe), the idea is to incease capacitance. Large capacitance
is a solution to the problem not a cause of problems, agree?

I don't know, but if that's the case, than a thinner medium between the mag
mount and the roof would have a higher capacitance than a thicker one, like
felt. Or it least I think it would... If so, than Saran Wrap might be the
answer.

Dave- Hide quoted text -

- Show quoted text -

KISS method
Use a stronger magnet
Art

Jimmie D wrote:

Interesting, when I replaced the mica insulator on a screen bypass cap with
Teflon the capacitance increased. I guess this is because the Teflon was
considerably thinner than the mica.

That would be the reason. The dielectric constant of mica is around 5-7
depending on the type. So for the same thickness, mica would give you at
least 2-1/2 times the capacitance of Teflon.

Dielectric constants for a wide range of materials are readily available
on the web. Google is your friend.

Roy Lewallen, W7EL

ah well it was nice while it lasted
"John Doe" wrote in message
...
If you can't contribute anything positive to this question, then stay out
of it, with your trash!

I have a 10m base loaded mag mount antenna, that I had to put a piece of
felt over the magnet as not to scratch a new vehicle.

When I did this I apparently changed the capacitance between the mag mount
and the roof of the vehicle. Someone suggested that I might want to
replace the felt with either a large balloon or a large prophylactic as it
is thinner and the capacitance would then return to almost where it should
be.

Positive comments only!

too bad the topic dies
"John Doe" wrote in message
...
If you can't contribute anything positive to this question, then stay out
of it, with your trash!

I have a 10m base loaded mag mount antenna, that I had to put a piece of
felt over the magnet as not to scratch a new vehicle.

When I did this I apparently changed the capacitance between the mag mount
and the roof of the vehicle. Someone suggested that I might want to
replace the felt with either a large balloon or a large prophylactic as it
is thinner and the capacitance would then return to almost where it should
be.

Positive comments only!