On Sat, 29 Nov 2003 06:17:53 -0000, (gudmundur)
wrote:

I do sound work at horse shows, and would like to provide my audio source
to vehicles parked at the show. I have a real nice 100 milliwatt input
1.6mhz transmitter which shows about 60 milliwatts of output at 50 ohms.

I would like to build a transmitting antenna that would be 4 feet in length
and having the 3/8 24 thread at the bottom so I can fasten it into my hamstick
mag mount base.

I am thinking a 1 inch diameter wooden dowel 4 feet long, and wrapped evenly
from bottom to top with perhaps #22 wire.

Any idea how much wire it would take to begin to act like a 50 ohm impedance
at the base? Would you solenoid wind it bottom to top, or would it work better
with maybe a 4 inch high multilayered coil at the bottom and 3.5 foot steel
whip antenna.

You need one of Reg Edwards' utilities to work this out for you. He's
written a number of small programs for the PC that handle exactly this
kind of problem and they're available for free download. I can't
recall the URL off hand but just Google for "Reg Edwards" on the
newsgroup sci.electronics.design and that'll bring it up.
--

"I expect history will be kind to me, since I intend to write it."
- Winston Churchill

"gudmundur" wrote in message
...
I do sound work at horse shows, and would like to provide my audio source
to vehicles parked at the show. I have a real nice 100 milliwatt input
1.6mhz transmitter which shows about 60 milliwatts of output at 50 ohms.

I would like to build a transmitting antenna that would be 4 feet in
length
and having the 3/8 24 thread at the bottom so I can fasten it into my
hamstick
mag mount base.


The best range has been reported using a Part 15 antenna mounted high and
in the clear on a metal structure--20 feet of water pipe will do. Do a web
search
for "part 15 am antenna" and you will get a lot of hits.

Now, the problem with part 15 is the interpretation. Some field engineers
will
argue that the loading inductor wire length should be counted against
against
the three meter total length permitted for the antenna and "ground lead".
The
six foot "ground lead" is also subject to interpretation... If you look at
some
of the better commercial units, they use a shielded loading coil, with a
110
inch or so whip.

Pete

"gudmundur" wrote in message
...
I do sound work at horse shows, and would like to provide my audio source
to vehicles parked at the show. I have a real nice 100 milliwatt input
1.6mhz transmitter which shows about 60 milliwatts of output at 50 ohms.

I would like to build a transmitting antenna that would be 4 feet in
length
and having the 3/8 24 thread at the bottom so I can fasten it into my
hamstick
mag mount base.


The best range has been reported using a Part 15 antenna mounted high and
in the clear on a metal structure--20 feet of water pipe will do. Do a web
search
for "part 15 am antenna" and you will get a lot of hits.

Now, the problem with part 15 is the interpretation. Some field engineers
will
argue that the loading inductor wire length should be counted against
against
the three meter total length permitted for the antenna and "ground lead".
The
six foot "ground lead" is also subject to interpretation... If you look at
some
of the better commercial units, they use a shielded loading coil, with a
110
inch or so whip.

Pete

Popular Electronics magazine, Nov 1962, had a broadcast band transmitter
project: "RFD 100" (housed in a rural mailbox). The center loaded vertical
antenna may suit your purpose. It is constructed with two 53 inch lengths
of 1/2" copper pipe with a 8" diameter by 12" long loading coil wound with
88 turns of #20 wire between. Article has generous details on construction
and tune-up.
Ray
"gudmundur" wrote in message
...
I do sound work at horse shows, and would like to provide my audio source
to vehicles parked at the show. I have a real nice 100 milliwatt input
1.6mhz transmitter which shows about 60 milliwatts of output at 50 ohms.

I would like to build a transmitting antenna that would be 4 feet in
length
and having the 3/8 24 thread at the bottom so I can fasten it into my
hamstick
mag mount base.

I am thinking a 1 inch diameter wooden dowel 4 feet long, and wrapped
evenly
from bottom to top with perhaps #22 wire.

Any idea how much wire it would take to begin to act like a 50 ohm
impedance
at the base? Would you solenoid wind it bottom to top, or would it work
better
with maybe a 4 inch high multilayered coil at the bottom and 3.5 foot
steel
whip antenna.

I am not out to **** off the FCC, and with a mere 60 milliwatts of output
power at 50 ohms, I don't think anyone beyond 300 yards will even here it.
I do however want to be clearly heard on an A.M. car radio anywhere on the
show grounds. There are no local stations on 1600khz, or even anywhere
near
it, and since these shows are only in the daytime, I won't be competing
with
skywave, or 50kw clear channels.

Popular Electronics magazine, Nov 1962, had a broadcast band transmitter
project: "RFD 100" (housed in a rural mailbox). The center loaded vertical
antenna may suit your purpose. It is constructed with two 53 inch lengths
of 1/2" copper pipe with a 8" diameter by 12" long loading coil wound with
88 turns of #20 wire between. Article has generous details on construction
and tune-up.
Ray
"gudmundur" wrote in message
...
I do sound work at horse shows, and would like to provide my audio source
to vehicles parked at the show. I have a real nice 100 milliwatt input
1.6mhz transmitter which shows about 60 milliwatts of output at 50 ohms.

I would like to build a transmitting antenna that would be 4 feet in
length
and having the 3/8 24 thread at the bottom so I can fasten it into my
hamstick
mag mount base.

I am thinking a 1 inch diameter wooden dowel 4 feet long, and wrapped
evenly
from bottom to top with perhaps #22 wire.

Any idea how much wire it would take to begin to act like a 50 ohm
impedance
at the base? Would you solenoid wind it bottom to top, or would it work
better
with maybe a 4 inch high multilayered coil at the bottom and 3.5 foot
steel
whip antenna.

I am not out to **** off the FCC, and with a mere 60 milliwatts of output
power at 50 ohms, I don't think anyone beyond 300 yards will even here it.
I do however want to be clearly heard on an A.M. car radio anywhere on the
show grounds. There are no local stations on 1600khz, or even anywhere
near
it, and since these shows are only in the daytime, I won't be competing
with
skywave, or 50kw clear channels.