"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

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