"Merlin-7 KI4ILB" wrote in message
. ..
I just bought a 10 meter mobile rig (25 watt old radio shack rig).

I was planing on cutting down a 102" CB whip to 10 meter band.

Anyone know of any type of antenna that would work better?

Thanks
Joe
KI4ILB



A 1/8wl antenna mounted in the center of your roof will probably work better
than the 1/4 lambda antenna on the bumper.

It would not be mounted on the bumper.
My thinking is that since the first 1/3 of an antenna does the most
radiating, get it as far away from any metal (broadside) that you can.
It would be mounted in a stake-hole (one of the 4 square holes in each
corner of the truck bed.
Joe

A 1/8wl antenna mounted in the center of your roof will probably work
better
than the 1/4 lambda antenna on the bumper.

"Merlin-7 KI4ILB" wrote in message
news
It would not be mounted on the bumper.
My thinking is that since the first 1/3 of an antenna does the most
radiating, get it as far away from any metal (broadside) that you can.
It would be mounted in a stake-hole (one of the 4 square holes in each
corner of the truck bed.
Joe

A 1/8wl antenna mounted in the center of your roof will probably work
better
than the 1/4 lambda antenna on the bumper.


To each his own, but I don't agree with the "bottom" of the antenna doing
the radiating. The bottom, *if* I understand it correctly--and I am not
here to prove anything or start a flame war (I ain't got time for that
)--is the voltage portion, the top would be the current (RF) portion.
Witness what happens if you grab an antenna (dipole. The current at the
ends can reach levels to produce serious burns! Grab a mobile antenna below
the loading coil while transmitting. You won't feel a thing! Grab it at or
above the coil, it will burn the hell out of you ( X-numbers of milliamps of
RF current). The next thing is, IMHO, if your antenna is radiating from the
bottom, WHY would you even NEED the rest of the antenna? LOL! Next there's
those pesky ground proximities that tend to "grab" a signal and just spoil
everything.

Now I am not trying to start a war, prove anyone wrong, annoy anyone, or
engage in a "I'm-smarter-than-you-and-I'm-not-gonna-yield" etc, etc. I'll
yield because it is 1) not important to me) and 2) cuz I ain't got time to
get into a theory war today! But, I am just of the opinion that the RF
is where the thing will burn the crap out of you if you grab it!!! I've been
burnt plenty of times, and it ain't pleasant!!!

73

Jerry

Jerry wrote:
The bottom, *if* I understand it correctly--is the voltage portion,
the top would be the current (RF) portion.

Nope, for a 1/4WL mobile antenna, the feedpoint is the
high current, low voltage point. The tip top is the
low current, high voltage point. The thing that tends
to bite us is the high voltage.

Consider that the top portion of a mobile antenna can
be a low-radiation top hat while the bottom of the
antenna (high current section) is radiating very well.
--
73, Cecil http://www.w5dxp.com

The current at the
ends can reach levels to produce serious burns! Grab a mobile antenna below
the loading coil while transmitting. You won't feel a thing! Grab it at or
above the coil, it will burn the hell out of you ( X-numbers of milliamps of
RF current).

Jerry,

It's the high-voltage bits that bite you because your skin resistance
is so high it takes some substantial voltage to drive a noticable
current through you, but it doesn't take much current to give you a
nasty burn. The high-current parts of the antenna don't have enough
voltage to burn you.

Dan

On Mon, 23 Oct 2006 01:12:09 GMT, "Merlin-7 KI4ILB"
wrote:

I just bought a 10 meter mobile rig (25 watt old radio shack rig).

I was planing on cutting down a 102" CB whip to 10 meter band.

Anyone know of any type of antenna that would work better?

Thanks
Joe
KI4ILB


I know this is an old post, but I only just now found and read it,
so I hope it is of interest to someone, if not the original poster.

Now that that's over, (whew) I installed a 102" SS whip, spring, and
ball mount I got from Rat Shack on the side of my 94 Plymouth Sundance's
left rear fender, (the trunk lid is fiberglass so I couldn't mount it there)
and it works great as it was. I got a near perfect match across the 10 meter
band without a tuner and I didn't have to trim it one iota. If I needed,
there is a little room for adjustment in the mount as the whip is secured
with a hex head set screw in the mount. That should give enough wiggle room
to get a decent match without having to cut the whip.

I have a tuner, (a Drake MN-4) I use in the car, but I use in bypass
mode for 10 meters. It will tune the whip from 20 through 10 meters with an
SWR typically under 1.5:1 on all those bands. It won't tune to a useable SWR
for anything lower in frequency than 20 meters though, so I will have to
come up with another antenna that I can hopefully use with the same mount
for 40, and hopefully through 80 meters.

Again, I know this is a reply to a nearly 7 month old post, but I
hope it is of use to someone anyway.

Rob

"Rob" wrote in message
...
On Mon, 23 Oct 2006 01:12:09 GMT, "Merlin-7 KI4ILB"
wrote:

I just bought a 10 meter mobile rig (25 watt old radio shack rig).

I was planing on cutting down a 102" CB whip to 10 meter band.

Anyone know of any type of antenna that would work better?

Thanks
Joe
KI4ILB


I know this is an old post, but I only just now found and read it,
so I hope it is of interest to someone, if not the original poster.

Now that that's over, (whew) I installed a 102" SS whip, spring, and
ball mount I got from Rat Shack on the side of my 94 Plymouth Sundance's
left rear fender, (the trunk lid is fiberglass so I couldn't mount it
there)
and it works great as it was. I got a near perfect match across the 10
meter
band without a tuner and I didn't have to trim it one iota. If I needed,
there is a little room for adjustment in the mount as the whip is secured
with a hex head set screw in the mount. That should give enough wiggle
room
to get a decent match without having to cut the whip.

I have a tuner, (a Drake MN-4) I use in the car, but I use in bypass
mode for 10 meters. It will tune the whip from 20 through 10 meters with
an
SWR typically under 1.5:1 on all those bands. It won't tune to a useable
SWR
for anything lower in frequency than 20 meters though, so I will have to
come up with another antenna that I can hopefully use with the same mount
for 40, and hopefully through 80 meters.

Again, I know this is a reply to a nearly 7 month old post, but I
hope it is of use to someone anyway.

Rob

Thanks, I have my home up for sale, so I have not had time to mount the 10
meter rig in my truck yet. Besides the rig is in storage 300 miles away from
here.
I hope my home sells soon, I had to take down my tower and pack up most
everything I own to show the house... I think I am going thru withdrawl...

Im glad to hear that it works well, I may toss the analiser on the 11 meter
whip that is already on the truck. If it works out I may only need to add an
antenna switch.
I only use the 11 meter rig durring hurricane season but it would be nice
not to need to change antennas when I do need it. The truck also has a 2
meter colinear on it thats 6 feet tall or so. I would not mind adding
another HF antenna but 2 long antennas on it is enough.
Thanks again
Joe

"Rob" wrote in message
...
On Mon, 23 Oct 2006 01:12:09 GMT, "Merlin-7 KI4ILB"
wrote:

I just bought a 10 meter mobile rig (25 watt old radio shack rig).

I was planing on cutting down a 102" CB whip to 10 meter band.

Anyone know of any type of antenna that would work better?

Thanks
Joe
KI4ILB


I know this is an old post, but I only just now found and read it,
so I hope it is of interest to someone, if not the original poster.

Now that that's over, (whew) I installed a 102" SS whip, spring, and
ball mount I got from Rat Shack on the side of my 94 Plymouth Sundance's
left rear fender, (the trunk lid is fiberglass so I couldn't mount it
there)
and it works great as it was. I got a near perfect match across the 10
meter
band without a tuner and I didn't have to trim it one iota. If I needed,
there is a little room for adjustment in the mount as the whip is secured
with a hex head set screw in the mount. That should give enough wiggle
room
to get a decent match without having to cut the whip.

I have a tuner, (a Drake MN-4) I use in the car, but I use in bypass
mode for 10 meters. It will tune the whip from 20 through 10 meters with
an
SWR typically under 1.5:1 on all those bands. It won't tune to a useable
SWR
for anything lower in frequency than 20 meters though, so I will have to
come up with another antenna that I can hopefully use with the same mount
for 40, and hopefully through 80 meters.

Again, I know this is a reply to a nearly 7 month old post, but I
hope it is of use to someone anyway.

Rob


The long antenna probably tunes up on 10M because of the fiberglass trunk
lid. Had the lid been metal it would have been the responsibel for the
largest portion of the capacitance needed to resonate the antenna. Without
this capcitance the antenna will need to be longer than normal to achive
resonance on 10M. One advantage of this that you have noted is a better
match to 50 ohms. Longer antenna = greater L, fibergllass lid = less
capacitance which gives a higher LC ratio at resonance.

Jimmie

"Jimmie D" wrote in message
...

"Rob" wrote in message
...
On Mon, 23 Oct 2006 01:12:09 GMT, "Merlin-7 KI4ILB"
wrote:

I just bought a 10 meter mobile rig (25 watt old radio shack rig).

I was planing on cutting down a 102" CB whip to 10 meter band.

Anyone know of any type of antenna that would work better?

Thanks
Joe
KI4ILB


I know this is an old post, but I only just now found and read it,
so I hope it is of interest to someone, if not the original poster.

Now that that's over, (whew) I installed a 102" SS whip, spring, and
ball mount I got from Rat Shack on the side of my 94 Plymouth Sundance's
left rear fender, (the trunk lid is fiberglass so I couldn't mount it
there)
and it works great as it was. I got a near perfect match across the 10
meter
band without a tuner and I didn't have to trim it one iota. If I needed,
there is a little room for adjustment in the mount as the whip is secured
with a hex head set screw in the mount. That should give enough wiggle
room
to get a decent match without having to cut the whip.

I have a tuner, (a Drake MN-4) I use in the car, but I use in bypass
mode for 10 meters. It will tune the whip from 20 through 10 meters with
an
SWR typically under 1.5:1 on all those bands. It won't tune to a useable
SWR
for anything lower in frequency than 20 meters though, so I will have to
come up with another antenna that I can hopefully use with the same mount
for 40, and hopefully through 80 meters.

Again, I know this is a reply to a nearly 7 month old post, but I
hope it is of use to someone anyway.

Rob


The long antenna probably tunes up on 10M because of the fiberglass trunk
lid. Had the lid been metal it would have been the responsibel for the
largest portion of the capacitance needed to resonate the antenna. Without
this capcitance the antenna will need to be longer than normal to achive
resonance on 10M. One advantage of this that you have noted is a better
match to 50 ohms. Longer antenna = greater L, fibergllass lid = less
capacitance which gives a higher LC ratio at resonance.

Jimmie

He mounted the antenna on the fender (because the trunk was fiberglass).
With that in mind, how does the trunk lid being fiberglass lessen the
capacitance of the circuit?
Doesn't the fender 'take the place' of the trunk lid?
I would reccommend someone using a metal trunk lid as a mounting surface to
install some copper wire jumpers from the lid to the rest of the body. Some
folks even go ahead and install copper jumpers to join all parts of the body
to each other and to the frame, motor, and neg battery terminal.

snip

He mounted the antenna on the fender (because the trunk was fiberglass).
With that in mind, how does the trunk lid being fiberglass lessen the
capacitance of the circuit?
Doesn't the fender 'take the place' of the trunk lid?
I would reccommend someone using a metal trunk lid as a mounting surface
to
install some copper wire jumpers from the lid to the rest of the body.
Some
folks even go ahead and install copper jumpers to join all parts of the
body
to each other and to the frame, motor, and neg battery terminal.


I am the king of grounding..
One note on that...most tail pipes on cars/trucks are hung with rubber
hangers in the middle of them so that they can flex. What you end up with is
a large diameter pipe (sometimes they match up on a frequency that you use),
mostly around 10 meter band but I guess It could be any number of
frequency's depending on the length of pipe)
I have found cases where the radio was picking up, what sounded like
ignition noise but after the tail pipe was grounded in a couple of places,
the noise dissapeared.

Joe