Painted Predator Antenna

[tvaverde]

I finished painting my predator antenna flat black .
I could not get the SWR's lower than 3.8 on any Chanel. I have 18' of R213 coax .
Using a SO239 for now. The antenna is mounted behind my back glass on my pick up bed , rite in the middle. The bottom shaft is 17" and the coil Is 3/4 above the roof line. With the whip all the way in the antenna I get a SWR of 3.8. With the whip all the way out I get SWR of 4.
I screwed in a 102" whip in its place just to make sure the coax and mount where good and the highest SWR reading was 1.3 on any Chanel .
Any ideas on what could be wrong.
Thanks in advance .

 

[The DB]

Was it tune able before you painted it?


The DB

 

[buickid]

What kind of paint? The paint might be slightly conductive. Did you paint the insulator?

 

[Brake Weight]

I'd take a guess and say its the paint. Was it tunable before the paint?

 

[tvaverde]

Regular flat rustolem. I taped off the insulator and even taped up a little of the coil and shafts to avoid shorting out the antenna.

It's a new Antenna and I wasn't smart enough to set up the SWR's before I painted it.

Just want to make sure there is nothing else that could cause the problem before I strip the paint . .

 

[Beetle]

Definitely sounds like something's conductive that shouldn't be. Most "flat black" paint compounds contain a whole lot of carbon black, which is highly conductive.

Good luck.

 

[AudioShockwav]

The Stingers on the Antennas are always long, Kale sends them that way.

With the whip all the way in the antenna I get a SWR of 3.8. With the whip all the way out I get SWR of 4.

Right now it sounds like you whip is too long, and needs to be cut down, as long as you made sure there are no shorts across any insulator just go ahead and tune the antenna as you would normally with a SWR meter.
As you remove length from the whip, you should see SWR drop, you have demonstrated this already by the above statement.
You can see that the SWR is better as you made the overall antenna shorter.
Try to get it a low as you can within reason in the middle of the band you are talking on...example if you are using the standard 40 channels, you would want the lowest reading at ch 20, with a slight rise as you move up or down from there.

73
Jeff

 

[tvaverde]

Thanks Jeff, this was my conclusion. I just needed some one with more knowledge to assure me. I will try it when I get home.

 

[Lil'Yeshua]

You could test it with a length of suspended wire the same length as the stinger and see if the stinger is too long.

 

[Brake Weight]

Do you have any round steel stock small enough to fit in the hole? You could test a shorter piece before cutting down what you have.

 

[BOOTY MONSTER]

pics please

 

[tvaverde]

Good idea. I'll see if I have some round stock. I'll post up some pics when I get home tonight.

 

[2RT307]

I think I chopped off about 6 inches of the whip to get my 10-K tuned right. Ended up buying some bolt cutters at Harbor Freight, because that is one tough whip! Happy tuning.

73,
RT307

 

[Lil'Yeshua]

I used my Snapon adjustable hacksaw with a fine metal cutting blade on my Sirio whip. The whip needs to be held securely and then round off the cut end on a concrete block or other abrasive thingamajig

 

[tvaverde]

I'll probably take my pneumatic cut off wheel home with me tonight. Should make short work of it.