102" stainless steel whip?

[BIONIC_TEXAN88]

sorry guys for all the posts, kinda new to all this. a friend of mine has a spare 102" stainless steel whip laying around he said i could have. my question is how do these recieve in the 150 and 800 mhz bands. i want an external antenna for the truck(this one is free).i know he uses one on his truck for cb, but how will this work on my pro 90?

 

[safetyobc]

i don't know a lot about antennas but that sounds like a CB antenna. I would think that reception would be very poor in the 150 and 800mhz range. Just a guess though.

 

[Mike445]

If you are looking to receive the 150 or 800 bands with a 102" whip then you may as well use a jelly donut. The 102" whip is useless for anything other than 27mhz (CB) band. However, if you have a CB the 102" whip is a smokin antenna!! When I had one hooked up in my old car I could talk clear across the country when the skip conditions were good.
Mike :twisted:

 

[BIONIC_TEXAN88]

thanks yall. i knew it was a cb antenna, i tried my 4' fiberglass whips and they could recieve ok but my rubber ducky outperformed it. i figured maybe w/ the 102" being made of a different material i could get different results.

 

[ILbandit]

If you cut it down to about 20", it will do ok on the 150 bands. :lol:

 

[BIONIC_TEXAN88]

thanks for your input, but as always i am gonna try it anyhow just to see if theres a difference between my 4' fiberglass and the 120". i am still gonna shop around for a decent inexpensive mobile ant. when i get some spare cash. any recomendations?

 

[BIONIC_TEXAN88]

so 20" should make a decent scanner ant? i know i can get one of these 102" at RS for pretty cheap. all i would have to do was cut it down to 20".

 

[N_Jay]

thanks for your input, but as always i am gonna try it anyhow just to see if theres a difference between my 4' fiberglass and the 120". i am still gonna shop around for a decent inexpensive mobile ant. when i get some spare cash. any recomendations?

1) it all depends on what the 4 foot fiberglass antenna is.

I assume it is a CB antenna, but may be bottom, center, or top loaded, or may be contiuously wound. Will make a huge difference on how it works out-of-band (other than CB band).

2) 20" is about right for VHF high, but there are other bands.

3) When you get "some spare cash" you may want to pick up a book on antenna design.

That way you can know what you are compairing istead of jsut focusong on the length.

 

[W4KRR]

thanks for your input, but as always i am gonna try it anyhow just to see if theres a difference between my 4' fiberglass and the 120". i am still gonna shop around for a decent inexpensive mobile ant. when i get some spare cash. any recomendations?

Buy a dedicated scanner antenna and forget modifying a CB whip. It's less trouble and it will work better. Try BNC Antenna or Scanners Unlimited.

www.bncantenna.com
www.scannersunlimited.com

 

[KC4ZEX]

If you are looking for a cheap mobile ant about your best buy is a mag mount dual band 2meter 440 ant will work great on vhf and uhf and fair on 800. MFJ sells one for $17.00 mfj1724B. Also Lakeview antenna co at www.hamstick.com sells one an EDB-2 for about the same price.

 

[nmfire10]

a 19" whip with no coils is a match for VHF 1/4 wave and UHF 3/4 wave. It will work however you have no gain on VHF and very little on UHF. But as a low profile antenna for dual-band, it can't be beat. Performance will suffer in the 800 and low band areas. If the signal is strong enough, a jelly donut will pick it up, it is just a matter of how well and for how far away.

 

[ham612]

If you want to homebrew a spare mono band antenna from parts you have laying around, 2808 divided by the desired frequency in MHz will give the length required in inches. There is a huge variety of mounting options out there. One I like is an adapter that has 3/8 x 24 threads on one end (very common on CB antenna mounts), and a set-screw that will accept a whip of desired length, on the other. These are around a dollar and a half at hamfests and some Radio Shack stores.

You also might try building a j-pole. There is very little cost involved and plans are all over the net for these, just do a google search.

MS

 

[BIONIC_TEXAN88]

thanks all for the help. well, i was using the 102" for my cg ant. i finally got some time to test it out on my swr meter and results werent great at all. i had at least 3:1 across the band. i put back on my 4' firestick and got 1.3:1 across the band. so, i ended up cutting the 102" down to 20" and wasnt impressed for 150 mhx band. does antenna diameter matter? i just cut 20" up from threads(fat part of ant.) do i need to use 20" of the skinnier part(top) and reweld it to the threads?

 

[nd5y]

What frequency are you trying to cut it for and what kind of mount is it on?
To get 1/4 wavelength use the formula L=2808/f
L is length in inches and f is the frequency in MHz.
Depending on what kind of mount you have you should measure
the length from the tip of the antenna to wherever the grounded part
of the mount ends or the end of the coax shield. That could be 0
to several inches subtracted from the whip length depending on the mount
and if it has a spring, etc.

Tom

 

[BIONIC_TEXAN88]

i am just trying to pick up the 150 mhz band. so i guess about 18".

 

[ILbandit]

Here is the easiest way I have found to figure out length/frequencies....
http://hotspotcb.com/cbshop/techtips/ANTtool.html

 

[00buck]

Even though the 102" is a CB antennna it will recieve 150mhz fairly well. I used one for 8 years. It picked up 150mhz better than my RS mobile scanner antenna. It was excellent for 46/49mhz and even did a good job on 800mhz.

 

[BIONIC_TEXAN88]

i might have to try that again, the 1st time wasnt successful, but i will try it one more time.

 

[N_Jay]

i might have to try that again, the 1st time wasnt successful, but i will try it one more time.

Unless you know how strong the signal is, you have no way to know how well your antenna system is working.

All the trying in the world will just build superstitions not knowlege!

 

[BIONIC_TEXAN88]

true, i think i have a pretty good feeling on signal strength im my area. i am just trying to figure out a way to only have 1 antenna mounted on my truck instead of two, just dont want to look like a rolling antenna. i know this is a compromise though.