Hey all,

Would an air-gap tuning capacitor intended for transmitting hook up any
differently from an air-gap tuning capacitor intended for receiving? I
built a project following the schematic for a commercial product, but the
(intended for transmitting) capacitor doesn't like being hooked up with the
stator grounded. Can't figure out how to make it work the way the schematic
is drawn, so I ungrounded the stator and take the input for the amplifier
from there instead of the rotor. And doing this, it works fine. Anyone
have any input? I'm all ears...

Thanks,

Dave

"Dave" wrote in message
...
Hey all,

Would an air-gap tuning capacitor intended for
transmitting hook up any differently from an air-gap
tuning capacitor intended for receiving? I built a
project following the schematic for a commercial product,
but the (intended for transmitting) capacitor doesn't like
being hooked up with the stator grounded. Can't figure
out how to make it work the way the schematic is drawn, so
I ungrounded the stator and take the input for the
amplifier from there instead of the rotor. And doing
this, it works fine. Anyone have any input? I'm all
ears...

Thanks,

Dave

Its not the cap. The main difference between receiving
and transmitting variable air capacitors is the voltage
rating. Since transmitting capacitors are made for higher
voltages they have greater plate spacing and consequently
larger plates for the same capacitance. without seeing the
circuit I can't guess as to what is wrong.


--
---
Richard Knoppow
Los Angeles, CA, USA

Dave wrote:
Hey all,

Would an air-gap tuning capacitor intended for transmitting hook up any
differently from an air-gap tuning capacitor intended for receiving? I
built a project following the schematic for a commercial product, but the
(intended for transmitting) capacitor doesn't like being hooked up with the
stator grounded. Can't figure out how to make it work the way the schematic
is drawn, so I ungrounded the stator and take the input for the amplifier
from there instead of the rotor. And doing this, it works fine. Anyone
have any input? I'm all ears...

Thanks,

Dave



No difference on the hook up question.

If you ground the stator the the shaft to the rotor will be "hot" and
that is probably your problem.
You can operate that way but you have to use an insulated coupling on
the shaft to the rotor.

Depending on the use, even that might give you trouble.

On Apr 21, 10:40 pm, "Dave" wrote:
Hey all,

Would an air-gap tuning capacitor intended for transmitting hook up any
differently from an air-gap tuning capacitor intended for receiving? I
built a project following the schematic for a commercial product, but the
(intended for transmitting) capacitor doesn't like being hooked up with the
stator grounded. Can't figure out how to make it work the way the schematic
is drawn, so I ungrounded the stator and take the input for the amplifier
from there instead of the rotor. And doing this, it works fine. Anyone
have any input? I'm all ears...

Thanks,

Dave

Most air variables are rotor grounded,,,stator floating ...Frame
grounded same as rotor.. HS

The stator assembly is usually insulated using a ceramic
like insulation, or phenolic. It is normally the "hot"
side of the capacitor. The rotor assembly and shaft are
usually part of the frame, and is grounded when mounted
to a metal chassis.

Pete

On Apr 21, 11:40�pm, "Dave" wrote:

Would an air-gap tuning capacitor intended for transmitting hook up any
differently from an air-gap tuning capacitor intended for receiving?

No.

*I
built a project following the schematic for a commercial product, but the
(intended for transmitting) capacitor doesn't like being hooked up with the
stator grounded.

What is the circuit, and why would you want to ground the stator
instead of the rotor?

*Can't figure out how to make it work the way the schematic
is drawn, so I ungrounded the stator and take the input for the amplifier
from there instead of the rotor.

I'm not sure what you mean.

Most variable capacitors, transmitting as well as receiving, are
designed so the rotor is connected to the frame of the capacitor.

If one side of the capacitor is to be grounded, it is almost always
the rotor, because that means the capacitor can be mounted directly to
the chassis and the rotor shaft doesn't need an insulated coupling.

If neither side of the capacitor is to be grounded, the rotor and
frame must be insulated from ground. That means the capacitor can't be
mounted directly to the chassis and the rotor shaft needs an insulated
coupling.

*And doing this, it works fine. *Anyone
have any input? *I'm all ears...

Need more info on the application and the circuit.

73 de Jim, N2EY

"Dave" wrote in message
...
Hey all,

Would an air-gap tuning capacitor intended for transmitting hook up any
differently from an air-gap tuning capacitor intended for receiving? I
built a project following the schematic for a commercial product, but the
(intended for transmitting) capacitor doesn't like being hooked up with
the stator grounded. Can't figure out how to make it work the way the
schematic is drawn, so I ungrounded the stator and take the input for the
amplifier from there instead of the rotor. And doing this, it works fine.
Anyone have any input? I'm all ears...

Thanks,

Dave



Thanks, all, for your input the rotor being normally grounded to frame,
etc. This makes sense, as the rotor has threads for a nut to fasten it in
place against the chassis/case. Please don't take my silence as not
caring/listening-I'm fiddling with it trying to understand what I have in my
hands, and how to make it work. *All* of your input is greatly appreciated.
Each and every one of you. You have the experience I lack, and I value your
feedback.

Trying to put it all into action...

Dave