On Fri, 18 Mar 2005 03:41:27 GMT, Ed
wrote:



I have a vertical slide window in my ham shack. In order to feed my coax
fed antenna systems through it, I have made a 3/4" thick piece of partical
board, about 6" tall amd ,mounted a couple BNC feedthru adapters in it.
This works quite well for coax. The window frame itself is plastic.

I would like to use a balanced tuner in my shack, about 2 feet from the
window, and feed ladderline to my antenna.

Question: What is recommended to feed the ladderline through the
particle board? Could I just drill and mount a couple #6 brass bolts with
solder eyes on each side of the board and use it to connect ladder line, or
is something else recommended? Will this have any measurable effect on
efficiency?

Thanks.


Ed K7AAT

I use a couple of big ceramic feedthrough insulators from Surplus
Sales of Nebraska. They're mounted on a board in the bottom of my
window. The slight impedance bump from the feedthrough bolts seems to
have no effect on the ladderline. The settings on the tuner were the
same before and after installing the feedthroughs.

In another recent thread some recommended using two pieces of coax to
feed ladderline through a wall or whatever.

Another idea would be two double-female so-239 feedthrough's, plugging
the ladderline into each center hole with banana plugs (banana plugs
fit the center hole in an so-239 just fine).

Bob
k5qwg



Bob
k5qwg

[stuff cut]

Another idea would be two double-female so-239 feedthrough's, plugging
the ladderline into each center hole with banana plugs (banana plugs
fit the center hole in an so-239 just fine).

What is a "banana plug". I've seen it mentioned a few times but haven't
a clue.

Jerry

Jerseyj wrote:
What is a "banana plug". I've seen it mentioned a few times but haven't
a clue.

They are the connectors on the ends of your Simpson meter
leads. They have four springs that ensure a wiping action
and a snug fit in the sockets.
--
73, Cecil http://www.qsl.net/w5dxp


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A Google search for "banana plug" brought about 67,000 hits. The very
first one has lots of pictures. I'll bet more than a few of the others
do, too.

Roy Lewallen, W7EL

Jerseyj wrote:

What is a "banana plug". I've seen it mentioned a few times but haven't
a clue.

Jerry

Roy,
What wiould be the property of a polymer like acrilic or polycarbonate
to determine its effectiveness as an insulator or a dielectric?
Volume resistivity?

Tnx,
Ted KX4OM

On Fri, 18 Mar 2005 17:23:36 -0800, Roy Lewallen
wrote:

---snip---

Ted Bruce wrote:
Roy,
What wiould be the property of a polymer like acrilic or polycarbonate
to determine its effectiveness as an insulator or a dielectric?
Volume resistivity?

Tnx,
Ted KX4OM

Volume resistivity is a useful measure only at DC.

To determine a dielectric's lossiness at RF, look at the loss tangent,
dissipation factor, or power factor. Loss tangent and dissipation factor
are the same thing, and when loss is low, power factor is also the same
for practical purposes. You'll find these in tables and descriptions of
the electrical properties of insulators. Some searching will usually
turn them up on the web if you don't have access to the appropriate
reference books. Note that the loss properties are usually a function of
frequency, so use the value at approximately the frequency of interest.

In some situations, the capacitance of the dielectric can be important,
such as when you're using it as a coil form or antenna covering. For
that, look at the dielectric constant or relative permittivity (which
are the same thing). This also changes somewhat with frequency.

Roy Lewallen, W7EL

I should also mention that the requirements for an insulator depend
heavily on the application. An insulator which results in a lot of loss
when a large electric field is present might produce negligible loss
when the field is weak. For example, an insulator at the base of a very
short or half wavelength high vertical, or at the end of a dipole, has
to be pretty good in order to minimize loss, because the electric field
is high at those points. On the other hand, a poor quality insulator is
just fine at the base of a quarter wave high vertical or the center of a
half wave dipole, since the electric field is low at those points.

Roy Lewallen, W7EL

Thanks. I have a 70's vintage Standard Handbook for Electrical
Engineers somewhere. It may list the materials and dissipative
factors.

Ted KX4OM
On Tue, 29 Mar 2005 12:26:01 -0800, Roy Lewallen
wrote:

I should also mention that the requirements for an insulator depend
heavily on the application. An insulator which results in a lot of loss
when a large electric field is present might produce negligible loss
when the field is weak. For example, an insulator at the base of a very
short or half wavelength high vertical, or at the end of a dipole, has
to be pretty good in order to minimize loss, because the electric field
is high at those points. On the other hand, a poor quality insulator is
just fine at the base of a quarter wave high vertical or the center of a
half wave dipole, since the electric field is low at those points.

Roy Lewallen, W7EL

I see 31 Mix snap-on beads listed by DXEngineering as effective in reducing
ignition noise by placing them on ignition wires. (0.275 inches)

I have several questions about their application for ignition wires:

1. Where along the wire should they be placed (at the plug, at the
distributor, middle of wire)?

2. Should they be stacked next to each other for better effect (series
butted up against one another) and if so, how many, and again, where along
the wire?

3. How many should be used and as above, how should they be "clustered"?

They come in packs of 10 and since I have a For Taurus ('95) 3.0 V6, I have
6 wires to deal with. 2 packs would yield 20 chokes, for example, and
perhaps a silly way to look at it would be to put one at each end of each
wire and one in the middle of each wire, using 3 per wire or 18 of the 20
available.

4. Are these likely to be significant help on either HF or VHF?

5. Can anyone recommend a really good set of ignition wires for best RFI
suppression?

(and yes, I'm aware of the fuel pump noise problem...but I'm concentrating
on ignition noise at the moment)

TIA

....hasan, N0AN

On Wed, 30 Mar 2005 06:33:36 -0600, hasan schiers wrote:

I see 31 Mix snap-on beads listed by DXEngineering as effective in reducing
ignition noise by placing them on ignition wires. (0.275 inches)

I have several questions about their application for ignition wires:

1. Where along the wire should they be placed (at the plug, at the
distributor, middle of wire)?

2. Should they be stacked next to each other for better effect (series
butted up against one another) and if so, how many, and again, where along
the wire?

3. How many should be used and as above, how should they be "clustered"?

They come in packs of 10 and since I have a For Taurus ('95) 3.0 V6, I have
6 wires to deal with. 2 packs would yield 20 chokes, for example, and
perhaps a silly way to look at it would be to put one at each end of each
wire and one in the middle of each wire, using 3 per wire or 18 of the 20
available.

4. Are these likely to be significant help on either HF or VHF?

5. Can anyone recommend a really good set of ignition wires for best RFI
suppression?

(and yes, I'm aware of the fuel pump noise problem...but I'm concentrating
on ignition noise at the moment)

TIA

...hasan, N0AN

Buy a package. Try it. Report back to the news group what you observed.