5/8 wave 2 meter antenna

[KD8HQY]

ok so i have asked questions about making a Wilson Lil Will 11 meter antenna into a 2 meter antenna and was advised against it.

so now i am thinking of trying to make one out of my old 102 whip i have laying around.

since i don't need it i figured i would get on and ask about doing this.

my question is what would be the total length i would need for it to be a 5/8 wave antenna.


i am terrible at math thats why i am here asking the question.

any help would be greatly appreciated.

i have a mag mount and also a few bee hive mounts in stock already.

yes i am being cheap, i don't have the extra cash right now to buy another antenna so i figured why not reuse what i have that i am no longer using.


thanks and 73`s
KD8HQY,, Lee

[KB1PRQ]

585/freq

Its gonna need to be around 48''

[KD8HQY]

585/freq

Its gonna need to be around 48''

thanks.. i have seen around the net that most are around the 54" but i also noticed they have about 4 inches of wrapped copper wire on the base of the antenna and waned to make sure that i didnt need to be actually longer than 54" since i will be using just a S.S. Whip

[AB8ZL]

A 5/8 whip will require a matching coil at the base in order to get a 50 ohm impedance.

See this thread for more information.
http://forums.qrz.com/showthread.php?t=44540

[K8ERV]

I have an interesting VoCom antenna bot long ago at Dayton, where it was demonstrated. There is a coil above the BNC, then a telescoping whip. I can't see into the coil, but think there is a cap feeding a tap, as is common with a 5/8.

With the whip collapsed, it is a matched 1/4 wave, TOTAL overall length of 8".

When extended, it is a matched 5/8, TOTAL overall length of 48".

Makes comparison easy,and the 5/8 works Great!

Don't know if VoCom is still in business.

TOM K8ERV Montrose Colo

[K7JEM]

I have an interesting VoCom antenna bot long ago at Dayton, where it was demonstrated. There is a coil above the BNC, then a telescoping whip. I can't see into the coil, but think there is a cap feeding a tap, as is common with a 5/8.

With the whip collapsed, it is a matched 1/4 wave, TOTAL overall length of 8".

When extended, it is a matched 5/8, TOTAL overall length of 48".

Makes comparison easy,and the 5/8 works Great!

Don't know if VoCom is still in business.

TOM K8ERV Montrose Colo

The same coil that matches a 5/8 will also serve as a loading coil for a shortened antenna. A typical base "loaded" 5/8 antenna for 2M has a coil of wire that is about 9" long, in a 1.25 inch coil, IOW, several turns.

That coil makes the antenna look like a 3/4 wave electrical length, which matches to 50 ohms pretty well. The coil doesn't radiate much, so the 5/8 wave section does the actual radiation.

That coil can be used as a 6M loading coil (discussed elsewhere), or a 2M loading coil for a short (8" or so) antenna. The short antenna will be inefficient, but work OK, for what it is.

Joe

[K7FE]

Consider keeping the 102" whip as is.

When you advance to HF mobile, you will need a whip. Screwdriver antenna makers usually do not ship a whip with them and expect you to provide your own. The 102" whips are becoming more difficult to obtain locally, depending on where you live.

A 102" whip may be cut down for a 1/4 wave 6 meter antenna, (or 5/8 2 meter) but will be a little stiffer than desired for mobile, depending on the individual whip.

A 1/4 wave whip for 2 meters is more practical from a size and performance standpoint and will work about as well as the 5/8 wave. They may be made from fence wire, welding rod, soft copper home wiring, etc. Construction sites routinely throw away 20 inch lengths of #12 or #14 copper wire that will work well as 1/4 wave antennas. (ask permission to scrounge first!)

I use soft copper, place one end in a vice, the other end in my drill and spin it for a few seconds while stretching the wire. This will straighten the wire and "work harden" it so it is stiffer.

Keep building.

73,
Terry, K7FE

[W9GB]

I have asked questions about making a Wilson Lil Will 11 meter antenna into a 2 meter antenna and was advised against it.

Lee -

The ideal conversion in the 1970s was the surplus Antenna Specialists CB antenna (and its clones)
that had loading coils 3 to 4 inches in height. I still routinely find these antennas at garage sales, etc.
Here is an example of that style (this is a low-band VHF for land-mobile service)
on eBay - Item number: 320260336013

These articles can be found in Ham Radio, CQ, 73 and QST magazines of that 1975-1979 period.
I have not looked at the Wilson antenna, but many of these current CB designs are different --
so would not be easy to modify/adopt.

144-MHz antenna, 5/8-wavelength built from CB mobile whip (HN) by WB4WSU
Ham Radio magazine, June 1974, page 67

w9gb

[W6SEL]

"I have asked questions about making a Wilson Lil Will 11 meter antenna into a 2 meter antenna and was advised against it."


i had the same cb mag mount antenna and at the time i was broke so i had to make it work with my 440 radio. I decided to match the antenna to the uhf rig. I used a dual sweep swr/wattmeter to get the most forward output wattage and the least movement from the swr needle for a near 1.1:1 ratio at my working frequency of 448.400mhz.
I cut the whip down to around 6 1/4 inches before i got the lowest swr reading. I was cutting small pieces at a time of course. I tested it and it hits the local repeaters and its not noisy so i can deal with that antenna until i can afford to buy a real gain antenna.
One thing i did notice is that the swr gets pretty high around 2 mhz up or down of the frequency that i matched the antenna to. I was'nt gonna be changing frequencies anyway. i'm only matched to my repeater frequency so it was good enough for me temporarily.
Anyways good luck and i hope it works out for you

[K7ZEM]

if i might say i might fade like a sigh if stay you minimize my movement anyway I must pursuade you another way!@!!!!!! pushin shive pushin shove............... there's no love in fear