That's why the contact is spring-loaded in some way.

"Ken Scharf" wrote in message
.. .
The biggest problem with a home brew rotor inductor
is going to be a low resistance contact with no
dead spots as the coil is rotated.

Airy R. Bean wrote:
That's why the contact is spring-loaded in some way.

"Ken Scharf" wrote in message
.. .

The biggest problem with a home brew rotor inductor
is going to be a low resistance contact with no
dead spots as the coil is rotated.



But if you need to install the tuner outdoors
remote controled via servo motors, guess how
long that sliding tap will give good contact?
At least sealed relays can be used for the
tap switch.

"Gregg" wrote in message
news:5cAld.151301$df2.57508@edtnps89...
LOL! OK, ;-)

Delrin rod, Acrylic pipe/rod, PVC plumbing (not to be used for VHF), is
key to the project.

There are many pubs out there on making variable capacitors, the ARRL
Radio Amateur's Handbook, and lots on the net.


There are? In the Handbook?


Hmmmm. Okay, thanks.

John

"Leon Heller" wrote in message
...
"Tim Wescott" wrote in message
...
Leon Heller wrote:
"Gregg" wrote in message
news:t4eld.149312$df2.42254@edtnps89...

I stumbled across a few at surplus outlets, I'll see if I can dig up
URL's. $50 to $150 USD, depending on KW rating.

You can build your own fairly simple though, for a lot less :-)


An old-timer I used to know made his own from plastic drain pipe. He
used a lathe for cutting a spiral grove in the pipe for the wire, and
machined most of the other parts himself.

73, Leon
I'm not sure I'd qualify anything requiring a machine lathe as being
"simple".

It is if one has a lathe. 8-)


That's not true. You haven't taken my capabilities into consideration. Even
if I had a lathe, I wouldn't know how to use it.

John

If you don't have any technical capabilities, RU a CBer?

"John Smith" wrote in message
. net...
That's not true. You haven't taken my capabilities into consideration.
Even
if I had a lathe, I wouldn't know how to use it.

ON5MJ wrote:

Thank you again all OM for your interesting replies.

This one from Ken could be worth the effort of investigation. I also thank
Bob who replied me personnally.

Did somebody try to replace a roller coil by a serie made of a tapped coil
and a variable capacitor ?

73 de Jacques - ON5MJ


You could do that, but again, if you have enough other adjustments you
can probably make the fine adjustments on the caps.

My first antenna tuner, which I used for several months, was just an
L-network with a tapped coil (with an alligator clip) and a variable
cap. By reversing the direction of the thing and dinking around it
always worked for me -- and since it was on an open piece of aluminum I
could hear, smell and see when I was putting too much RF into it for the
little broadcast tuning cap!

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

......and now I understand your approach to DSP

"Tim Wescott" wrote in message
...
My first antenna tuner, which I used for several months, was just an
L-network with a tapped coil (with an alligator clip) and a variable
cap. By reversing the direction of the thing and dinking around it
always worked for me -- and since it was on an open piece of aluminum I
could hear, smell and see when I was putting too much RF into it for the
little broadcast tuning cap!

Airy R. Bean wrote:

.....and now I understand your approach to DSP

"Tim Wescott" wrote in message
...

My first antenna tuner, which I used for several months, was just an
L-network with a tapped coil (with an alligator clip) and a variable
cap. By reversing the direction of the thing and dinking around it
always worked for me -- and since it was on an open piece of aluminum I
could hear, smell and see when I was putting too much RF into it for the
little broadcast tuning cap!



Why thank you. That's very nice.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

I can assure you that it is not. However, if it makes you feel
better then please deceive yourself on that matter as you undoubtedly
do upon the religious beliefs of DSP.

"Tim Wescott" wrote in message
...
Airy R. Bean wrote:
.....and now I understand your approach to DSP
"Tim Wescott" wrote in message
...
My first antenna tuner, which I used for several months, was just an
L-network with a tapped coil (with an alligator clip) and a variable
cap. By reversing the direction of the thing and dinking around it
always worked for me -- and since it was on an open piece of aluminum I
could hear, smell and see when I was putting too much RF into it for the
little broadcast tuning cap!
Why thank you. That's very nice.

Airy R. Bean wrote:

I can assure you that it is not. However, if it makes you feel
better then please deceive yourself on that matter as you undoubtedly
do upon the religious beliefs of DSP.

I will! Particularly since when _I_ build a system with DSP it
generally works exactly as I've predicted it will. If I'm deceived,
then so is God -- are you saying that God is deceived by how DSP works?

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com