WHAT IS THE "COIL" USED TO MATCH A 5/8 WAVE VERTICLE? i MEAN WHAT IS IT
MADE FROM AND WHERE DO YOU GET THEM?

wrote:
WHAT IS THE "COIL" USED TO MATCH A 5/8 WAVE VERTICLE? i MEAN WHAT IS IT
MADE FROM AND WHERE DO YOU GET THEM?

The end feedpoint impedance of a 5/8WL vertical is about
150 - j600 ohms. The coil is used as a loading coil to cancel
that capacitive reactance and is usually tapped and fed at
the 50 ohm point. Construction details for a 2m 5/8WL mobile
antenna are contained in "The ARRL Antenna Book" which is
an excellent first book on the subject of antennas.

Here's what EZNEC sez about a 1/4WL Vs a 5/8WL vertical.

1/4WL 5/8WL
-0.14 dBi at 26 deg. TOA 0.1 dBi at 26 deg.
-0.75 dBi at 17 deg. 1.4 dBi at 17 deg. TOA

Whether that 2 dB advantage at 17 deg. is worth all that
extra effort depends upon what kind of operating you do.
It can make a difference for CW DX.
--
73, Cecil http://www.qsl.net/w5dxp


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Cecil Moore wrote:
wrote:
WHAT IS THE "COIL" USED TO MATCH A 5/8 WAVE VERTICLE? i MEAN WHAT
IS IT
MADE FROM AND WHERE DO YOU GET THEM?

The end feedpoint impedance of a 5/8WL vertical is about
150 - j600 ohms. The coil is used as a loading coil to cancel
that capacitive reactance and is usually tapped and fed at
the 50 ohm point. Construction details for a 2m 5/8WL mobile
antenna are contained in "The ARRL Antenna Book" which is
an excellent first book on the subject of antennas.

Here's what EZNEC sez about a 1/4WL Vs a 5/8WL vertical.

1/4WL 5/8WL
-0.14 dBi at 26 deg. TOA 0.1 dBi at 26 deg.
-0.75 dBi at 17 deg. 1.4 dBi at 17 deg. TOA

Whether that 2 dB advantage at 17 deg. is worth all that
extra effort depends upon what kind of operating you do.
It can make a difference for CW DX.
--
73, Cecil http://www.qsl.net/w5dxp


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Is that the same as a 1/4 ground plane vs 5/8 ground plane? It is just
I have seen 5/8 antennas advertised with gain.
On another topic, Would it be bad to use RG6 for the antenna and radio?

Cecil, W5DXP wrote:
"Construction details for a 2m 5/8 WL vertical mobile antenna are
contained in "The ARRL Antenna Book" which is an excellent first book on
the subject of antennas."

I agree the "ARRL Antenna Book" is a must have! Mine is the 19th edition
and I didn`t find the 2-meter band 5/8-wavelength vertical. But, I also
have the 1987 edition of the "ARRL Handbook". The 5/8-wavelength
vertical for 2 meters appears on page 33-28 of that book.

Best regards, Richard Harrison, KB5WZI

wrote:
Is that the same as a 1/4 ground plane vs 5/8 ground plane?

Yep.

It is just I have seen 5/8 antennas advertised with gain.

They have a slight amount of gain IAOI they have a good ground plane.
The additional gain of a well designed 5/8WL vertical is, IMO, only
important for HF CW DX and QRP digital work.

On another topic, Would it be bad to use RG6 for the antenna and radio?

"Bad" is relative. RG6 is 75 ohms. When I was in high school, RG6 &
RG11 were very popular. If a center-fed dipole has a feedpoint
impedance of 73 ohms, then 75 ohm coax results in a very low SWR
on the feedline. The mismatch, is this case, is at the source
and is not anything to worry about. Of course, your SWR meter,
calibrated for 50 ohms, will not display the correct SWR on the
75 ohm coax. In the '50's, if our transmitter's pi-net output
would "load", our system was working just fine. Most of us didn't
even own an SWR meter back then.
--
73, Cecil http://www.qsl.net/w5dxp


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Depends on what band the antenna is for.

K9SQG wrote:

Depends on what band the antenna is for.

Why?
- 'Doc

Cecil Moore wrote:
wrote:
Is that the same as a 1/4 ground plane vs 5/8 ground plane?

Yep.

It is just I have seen 5/8 antennas advertised with gain.

They have a slight amount of gain IAOI they have a good ground plane.
The additional gain of a well designed 5/8WL vertical is, IMO, only
important for HF CW DX and QRP digital work.

On another topic, Would it be bad to use RG6 for the antenna and
radio?

"Bad" is relative. RG6 is 75 ohms. When I was in high school, RG6 &
RG11 were very popular. If a center-fed dipole has a feedpoint
impedance of 73 ohms, then 75 ohm coax results in a very low SWR
on the feedline. The mismatch, is this case, is at the source
and is not anything to worry about. Of course, your SWR meter,
calibrated for 50 ohms, will not display the correct SWR on the
75 ohm coax. In the '50's, if our transmitter's pi-net output
would "load", our system was working just fine. Most of us didn't
even own an SWR meter back then.
--
73, Cecil http://www.qsl.net/w5dxp


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If my swr meter wont work with 75 ohm cable, should I use rg58 thsn if
I cant find rg8?

wrote:
If my swr meter wont work with 75 ohm cable, should I use rg58 thsn if
I cant find rg8?

You could probably recalibrate your 50 ohm SWR meter to
75 ohms. Or if all you are using it for is to make your
transmitter happy, leave it calibrated for 50 ohms. In
the latter case, you are not measuring SWR. When a 50
ohm SWR meter indicates 1:1, it is looking into 50 ohms
which is what the transmitter wants to see.
--
73, Cecil http://www.qsl.net/w5dxp


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Cecil Moore wrote:
wrote:
If my swr meter wont work with 75 ohm cable, should I use rg58 thsn
if
I cant find rg8?

You could probably recalibrate your 50 ohm SWR meter to
75 ohms. Or if all you are using it for is to make your
transmitter happy, leave it calibrated for 50 ohms. In
the latter case, you are not measuring SWR. When a 50
ohm SWR meter indicates 1:1, it is looking into 50 ohms
which is what the transmitter wants to see.
--
73, Cecil http://www.qsl.net/w5dxp


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By the way, I bought a 2 meter/220/440 mhz swr/watt meter that reads
radiated/reflective power. Is this a good meter to set swr? Are these
hard to use?

I found some rg8/u and it is kind of expensive but the concensous seems
to be to use that if I want accuracy.