K40 Trunk Lip Mount Antenna

[redneck330]

I have a K40 Trunk Lip Mount Antenna on my wife's car with a Connex 3300HP but I cannot get the SWR below 2.5. I had this antenna on truck but went back "OLD SCHOOL" with a 102" whip. The SWR with that antenna and same radio ran between 1.1 to 1.6. This has me confused. Any suggestions?

[drdx]

Does the mount have a good ground connection? Is it lower on either end of the band, like maybe it needs to be shortened? If it is higher on 40 than on 1, it is too long. If it is lower on 40, it is too short. On the ground connection, make sure you scrape a little paint away and when you're done, if you have one, probe the mount to the body and make sure it has a good connection, with an ohm meter. -drdx

[redneck330]

I tried that and even checked ground from antenna base to PL-259......it's getting ground but it's not grounded out.

[rongstad]

I run a k40 mag mount and once a year I take it apart and make sure all the "insides" are nice and shiny. Don't know why but one of the screws always has alittle rust, truck is garage kept, never-never in the rain....lol. On second thought...did you cut the whip? It may be too short?

[redneck330]

I have never cut the whip. I thought on a K40 that you didn't have to cut the whip.

[rongstad]

Does the mount have a good ground connection? Is it lower on either end of the band, like maybe it needs to be shortened? If it is higher on 40 than on 1, it is too long. If it is lower on 40, it is too short. On the ground connection, make sure you scrape a little paint away and when you're done, if you have one, probe the mount to the body and make sure it has a good connection, with an ohm meter. -drdx

X2 with drdx.........I'd check the ground, especially where the allen screws clamp down on the trunk lip.

[redneck330]

I'll try that again......thanks a lot guys! :D

['Doc]

No antenna is going to present the same SWR, or other characteristics when moved from one place to another. Unless those 'places' are exactly alike, sort of. So, adjusting/tuning an antenna is a "given". If you don't have to do that you are just very lucky (buy me a lottery ticket!).
It's a good idea to make sure your antenna is getting/making good contact with the car's body. That is the other half of that antenna, you know. There are exceptions to that but you don't have one of them.
[There seems to be a preoccupation with 'grounding' lately. It is important, but it's far from being the 'answer' to most antenna problems.]
It's also nice to have one'a them antenna analyzers! The 'catch' to that is that they are not cheap. If you don't do a lot of antenna changing, it's sort of over-kill. Know someone who has one? Borrow it! They are also not 'plug-n-play', so borrow that instruction manual too. Some times the owners of those thingys are open to bribes to do all that stuff for you, (mine is beer)...
- 'Doc

[shadow]

Ground it. Most of my antenna problems go away when i ground them better. Last K40 that i installed with high SWR, i used a braid and grounded the antenna strait to the cars chassis.

Ground first, ask questions later. thats my new motto.

[super20dan]

this is odd cause the k40 is the only antenna i bever had any swr issue with on any install