102 in whip

[hotrod]

i wouldnt bumper mount it. that would lower the antenna performance
the tri mount is good and should work well

 

[yellowjacket78]

now one more thing. Would ya'll recommend running another ground to the chassis just to have a more solid ground or would the magnets be suffecient enough?

 

[hotrod]

personally if it was mine no i wouldnt. i think you wont see any difference
and even if there would be it would only be very minior.like the saying
goes if it anit broke dont fix it.

 

[mackmobile43]

now one more thing. Would ya'll recommend running another ground to the chassis just to have a more solid ground or would the magnets be suffecient enough?

If the coax leading from the mount has sufficient bonding to the chassis that is all that is required and that would be through the radios chassis via the negative lead from the radio and or radios mount to the chassis.

 

[yellowjacket78]

Ok I will leave it as it is. I am having another issue and that is squeling from the radio but it does it when I turn my box on. I am using an echo mic but when I hook any other mic it works fine. I know this section is for antennas but I figured I would ask anyways. Any suggestions?

 

[mackmobile43]

Try backing off the mic gain a bit on the radio and or mic, sounds like feedback.

 

[BOOTY MONSTER]

26.965 = 104.135 inches
27.205 = 103.216 inches
27.405 = 102.463 inches
I would not expect a 1:1 Swr with a 1/4. A good example is a 1/4 wave ground plane, with 4 90 degree radials i would expect to see about 30/35 ohms at the feed point, even tho the antenna is cut to the proper length.
If you pull the radials down to about a 45 degree angle, it will raise the feed point closer to 50 ohms.
Doc is correct, you do not always see a 1:1 Swr at resonance.
This would require a matching network.
For myself......I do not personally care for bumper mounts, too much reflect off of the metal of the car/truck
If you are Happy with the Tri Mag Mount on the roof I do not think you are going to gain much by hard mounting it.... unless you are running very high power levels. That is a different ball game.
Yes it will trim trees and everything else....but.


73
Jeff

i tried a 102 in the middle of my monteros roof and the vswr was 3.0+ . my stud mount adds about 1 1/2 inches of length to to the antenna for a total length of about 103 1/2 inches , so i was very very close to the 103.216 inches for the middle of the cb band mentioned above .

http://www.worldwidedx.com/cb-antennas/30479-10k-tunes-1-3____102-3-0-a.html

i was told i needed a spring or something to add a few inches of length to the antenna .
my mount is a firestick DM4 using lug connectors , not a 239/259 .
so whats the deal ?
is my montero unique ?
the 10k tuned fine , simply changed antennas .

 

[BOOTY MONSTER]

26.965 = 104.135 inches
27.205 = 103.216 inches
27.405 = 102.463 inches
I would not expect a 1:1 Swr with a 1/4. A good example is a 1/4 wave ground plane, with 4 90 degree radials i would expect to see about 30/35 ohms at the feed point, even tho the antenna is cut to the proper length.
If you pull the radials down to about a 45 degree angle, it will raise the feed point closer to 50 ohms.
Doc is correct, you do not always see a 1:1 Swr at resonance.
This would require a matching network.
For myself......I do not personally care for bumper mounts, too much reflect off of the metal of the car/truck
If you are Happy with the Tri Mag Mount on the roof I do not think you are going to gain much by hard mounting it.... unless you are running very high power levels. That is a different ball game.
Yes it will trim trees and everything else....but.


73
Jeff

i tried a 102 in the middle of my monteros roof and the vswr was 3.0+ . my stud mount adds about 1 1/2 inches of length to to the antenna for a total length of about 103 1/2 inches , so i was very very close to the 103.216 inches for the middle of the cb band mentioned above .

http://www.worldwidedx.com/cb-antennas/30479-10k-tunes-1-3____102-3-0-a.html

i was told i needed a spring or something to add a few inches of length to the antenna .
my mount is a firestick DM4 using lug connectors , not a 239/259 .
so whats the deal ?
is my montero unique ?
the 10k tuned fine , simply changed antennas .

 

[W5LZ]

Booty',
What you saw with that 102" is about as normal as it gets. What you saw with the 10K is also about as normal as it gets. What's the difference? It deals with reactances in the antenna system. I won't even try to explain that, it get's to 'involved'/'deep', and I'm too lazy. It also deals with antenna 'Q'.
- 'Doc

(I won't make any comments about your Montero. )

 

[BOOTY MONSTER]

Booty',
What you saw with that 102" is about as normal as it gets. What you saw with the 10K is also about as normal as it gets. What's the difference? It deals with reactances in the antenna system. I won't even try to explain that, it get's to 'involved'/'deep', and I'm too lazy. It also deals with antenna 'Q'.
- 'Doc

(I won't make any comments about your Montero. )

soooooo .................... i would have been perfectly fine using the 102 with a 3.0+ vswr ? LOL
the shop was using a mfj-259b to get the 1.3 and 3.0+ measurments @ 27.205

 

[NY739 Mobile]

i tried a 102 in the middle of my monteros roof and the vswr was 3.0+ . my stud mount adds about 1 1/2 inches of length to to the antenna for a total length of about 103 1/2 inches , so i was very very close to the 103.216 inches for the middle of the cb band mentioned above .

http://www.worldwidedx.com/cb-antennas/30479-10k-tunes-1-3____102-3-0-a.html

i was told i needed a spring or something to add a few inches of length to the antenna .
my mount is a firestick DM4 using lug connectors , not a 239/259 .
so whats the deal ?
is my montero unique ?
the 10k tuned fine , simply changed antennas .

I run a 102" ss whip ($20 from radio shack) on a 6" spring for a total of
108"...solid mount directlly behind the cab of my truck on the box rail ( one of the worst places, so im told) and my swr is 1.2:1 across all 40 and well above and below....as soon as i installed it i noticed a HUGE improvment over my last antenna( a mag mount wilson 1000) I've talked skip all over the US, canada, mexico, and even jamica..( sittin at aroun 1300ft in western NY) ..even heard alaska and hawaii come in today alittle bit but couldnt make contact...any way, if your swr was 3:1 it would lead me to believe that there was another issue at hand (coax,connection,etc...)
with the height of my truck and the 108" whip my total height is just under 14' feet so i rarley hit anything...mabye the ocassional tree branch..but the whip can take some serious abuse , I drove under an 11' bridge at around 60mph and forgot about my antenna, oops , but it didnt even hurt it...but any way....all im sayin is don't discount the whip..after all every mobile antenna on the market is comparred to the standard 1/4 wave....so simple yet so perfect.....good luck

 

[BOOTY MONSTER]

my truck is a hair over my head and in 6 ft 1 so a 102 with a spring/spacer winds up at 15 ft to the tip . i was gonna try it even though its 1 1/2 feet over legal here . but since it wouldn't tune and i didn't want to change the mounting location and i didnt want a spring i just put it off ........
the 102 and 10k were swaped back and forth a few times and checked and the tunings were consistant for eack so i dont think i had a coax /259 or stud/install issue . i guess i just wont know unless i put a spring or spacer on a 102 and check its tuning .
oh well .................... its on my to do list , LOL

 

[NY739 Mobile]

I hear ya, 15 feet is kinda pushin it...lol..
If i would have mounted mine to the roof of my F350sd it would have ended up around 16'+ so I took a shot and mounted behind the cab against my better judgement...i am glad i did though, it worked out well.and it looks good...I do notice when I pull my 12' work trailer ( which is a bit taller than my truck and all aluminum) my swr's creep up to 1.4:1, but I can live with that....i guess every vehicle acts different in every situation....good luck....
73's

 

[AudioShockwav]

Hey Booty, when you built your Booty Plane, you measured out the length of the vertical to the correct length, then you wound a coil and tapped it to get a flat SWR.
You can change feed point impedance several ways........
We always focus on the SWR meter when building antennas, but the MFJ can often tell you more.
They told you what the SWR was, but did not tell you what the R and X values were.
This is one way to change feed point impedance.

73
Jeff

By the way, i ripped that picture off of K0BG`s Web site......there is a ton and a half of good info over there, go have a look.
It will also provide good info about why a bumper mount is the least desirable place to mount a antenna.....keeeeeeeep reading.
KØBG.COM

 

[W5LZ]

Reading K0BG's site is very good advice, he does know what he's talking about. I also think you'll notice that he will draw a distinction between resonance and a good SWR. You'd do well to pay attention to that too.
- 'Doc