Geez...maybe he'll convert this over to U.S. measurement!


"Roger Conroy" wrote in message
...

"Moody1951" wrote in message
...
Please help me out with the math. What is the length of a 5/8s
wavelength
2
meter antenna? I've got something that might be able to be cut to the
freq.

Thanks

Lets assume you want a center frequency of 146 megahertz...

300/146=2.057945m (round it to nearest mm 2.058m)
2.058/8=0.25725m
0.25725x5=1.28625m (round it to nearest mm 1.286m)

Now I have a few questions...

How the ^%$#(*&$ do you get to even own a 2m radio without knowing how to
do
this ELEMENTARY calculation? Do you have a licence? Have you learnt
absolutely nothing? This formula is the first one in the book together
with
Ohm's Law!

73
Roger ZR3RC

On Tue, 6 Apr 2004 09:27:58 +0200, "Roger Conroy"
wrote:

Now I have a few questions...

How the ^%$#(*&$ do you get to even own a 2m radio without knowing how to do
this ELEMENTARY calculation? Do you have a licence? Have you learnt
absolutely nothing? This formula is the first one in the book together with
Ohm's Law!

Perhaps he took the test over a year ago, has only been using a HT,
and is now wanting to get into mobile use?

Let me ask you a few questions:

How far in advance of a turn are you required to use your turn signal?

What is the maximum distance you may enter a bike lane prior to making
a turn?

You may use your hi beams if a car coming towards you is more than
____ feet away, or if a car is in front of you in the same direction
as you, more than _____ feet away.

Gee, you don't know? How the &*^#*$@ did you get your drivers license?

Get the point?

Evan

To reply, remove TheObvious from my e-mail address.

Neat calculator at URL:
http://www.geocities.com/kk5hy/calc.html

You can cut it for hi, lo, or mid band

--
Incognito By Necessity (:-(

If you can't convince them, confuse them.
- - -Harry S Truman




"Moody1951" wrote in message
...
Please help me out with the math. What is the length of a 5/8s wavelength
2
meter antenna? I've got something that might be able to be cut to the
freq.

Thanks

Ok lets start this over again

Hi Moody,

The ansewr to your question, if you intend to use it on the upper portion of
the band (tuned to 146Mhz) would be 48.12 inches.

Aside from your asking antenna question here, also check out the ARRL
Handbook, as you will find the answers to simple questions, others get
annoyed at LOL

also visit the http://www.qsl.net/w4sat/antenna.htm website.

As far as the point you expressed Bob, I agree with you somewhat. Not all
Techs dont know anything. I have spoken to many Advanced/Extra that cant
figure out the length of a dipole for 40m, or how to program the memory in
the 2m radio. Even go as far as "you are not on frequency, and you dont need
to say over on a repeater". Now it makes me made when, me being a Tech needs
to answer these questions

Take in to the account of why many join the ham ranks. Not all are technical
minded people, or not yet atleast

73

Steve KC2GOG


"Moody1951" wrote in message
...
Please help me out with the math. What is the length of a 5/8s wavelength
2
meter antenna? I've got something that might be able to be cut to the
freq.

Thanks

The US tests are so easy that I can see the extra class people not knowing
the length of a 1/2 wave for 40 meters. I am only licensed Basic in Canada
and just for fun I did the extra class exam on the QRZ web site. Scored in
the mid 70% range with no studding and I am not the brightest light-bulb in
the tree. Especially when it comes to math.

"S" wrote in message
et...
Ok lets start this over again

Hi Moody,

The ansewr to your question, if you intend to use it on the upper portion
of
the band (tuned to 146Mhz) would be 48.12 inches.

Aside from your asking antenna question here, also check out the ARRL
Handbook, as you will find the answers to simple questions, others get
annoyed at LOL

also visit the http://www.qsl.net/w4sat/antenna.htm website.

As far as the point you expressed Bob, I agree with you somewhat. Not all
Techs dont know anything. I have spoken to many Advanced/Extra that cant
figure out the length of a dipole for 40m, or how to program the memory in
the 2m radio. Even go as far as "you are not on frequency, and you dont
need
to say over on a repeater". Now it makes me made when, me being a Tech
needs
to answer these questions

Take in to the account of why many join the ham ranks. Not all are
technical
minded people, or not yet atleast

73

Steve KC2GOG


"Moody1951" wrote in message
...
Please help me out with the math. What is the length of a 5/8s
wavelength
2
meter antenna? I've got something that might be able to be cut to the
freq.

Thanks

The US tests are so easy that I can see the extra class people not knowing
the length of a 1/2 wave for 40 meters. I am only licensed Basic in Canada
and just for fun I did the extra class exam on the QRZ web site. Scored in
the mid 70% range with no studding and I am not the brightest light-bulb in
the tree. Especially when it comes to math.

"S" wrote in message
et...
Ok lets start this over again

Hi Moody,

The ansewr to your question, if you intend to use it on the upper portion
of
the band (tuned to 146Mhz) would be 48.12 inches.

Aside from your asking antenna question here, also check out the ARRL
Handbook, as you will find the answers to simple questions, others get
annoyed at LOL

also visit the http://www.qsl.net/w4sat/antenna.htm website.

As far as the point you expressed Bob, I agree with you somewhat. Not all
Techs dont know anything. I have spoken to many Advanced/Extra that cant
figure out the length of a dipole for 40m, or how to program the memory in
the 2m radio. Even go as far as "you are not on frequency, and you dont
need
to say over on a repeater". Now it makes me made when, me being a Tech
needs
to answer these questions

Take in to the account of why many join the ham ranks. Not all are
technical
minded people, or not yet atleast

73

Steve KC2GOG


"Moody1951" wrote in message
...
Please help me out with the math. What is the length of a 5/8s
wavelength
2
meter antenna? I've got something that might be able to be cut to the
freq.

Thanks

"Moody1951" wrote in message
...
Please help me out with the math. What is the length of a 5/8s wavelength
2
meter antenna? I've got something that might be able to be cut to the
freq.


Others have given you the length. They failed to mention that the impedance
is not 50 ohms and you must match that to the coax/rig. You will have to
research that for yourself, but usually a coil is used in series with the
antenna at the base of it.

On Tue, 6 Apr 2004 19:29:45 -0400, "Ralph Mowery"
wrote:


"Moody1951" wrote in message
...
Please help me out with the math. What is the length of a 5/8s wavelength
2
meter antenna? I've got something that might be able to be cut to the
freq.

Others have given you the length. They failed to mention that the impedance
is not 50 ohms and you must match that to the coax/rig. You will have to
research that for yourself, but usually a coil is used in series with the
antenna at the base of it.

Also relevant:

The calculated length is close, but factors like material type,
thickness, etc, mean that the actual length could be a little
different. Electrical length is what counts, not physical.

Best bet is to take the calculated length as mentioned earlier, add a
little bit, and cut to that greater length. Then test the antenna with
an SWR meter, trim a little shorter, and test again to optimize SWR
across the band of interest. You will never hit 1:1 (more of a
theoretical goal) but below 1:1.5 across the 2M band is fine.

Start your testing at a low power, until you know the SWR is below
1:2.

Happy trails,
Gary (net.yogi.bear)
------------------------------------------------
at the 51st percentile of ursine intelligence

Gary D. Schwartz, Needham, MA, USA
Please reply to: garyDOTschwartzATpoboxDOTcom

Please help me out with the math. What is the length of a 5/8s wavelength
2
meter antenna? I've got something that might be able to be cut to the
freq.



You might try 5/8 of 2meters = 1.25Meters.
Add a bit for trimming and there you are.

Dave

Please help me out with the math. What is the length of a 5/8s wavelength
2
meter antenna? I've got something that might be able to be cut to the
freq.



You might try 5/8 of 2meters = 1.25Meters.
Add a bit for trimming and there you are.

Dave