wwiifirearms

I had a Francis 4.5' Fiberglass Antenna and had good SWR around 1.4. Someone broke it off while my jeep was parked

I just went and bought a 4' firestik and installed it and my SWR is over 3 accross all channels!!! Obviously I can't use it like this without damage to the radio.

Since nothing changed in the mount, location, coax, or radio, what could cause this?

I took the mount off and ground off more powder coat to make certain I had good ground (but I don't know how to check the ground is good). No change.

Any ideas or procedures for testing potential issues?

-wwiifirerms

wwiifirearms

Update: I moved the stud to the second hole in the tereflex mount, which I had not removed the powder coat from, and it dropped to around 2. Better, but not good yet. My guess is I have problem with my stud shorting out. With it in the other mount hole, I am guessing it isn't shorting, but now the shield isn't properly grounded.

Am I right to think the stud should allow the shield to ground to the mount, but not allow the stud itself to ground?
-wwiifirearms

wwiifirearms

Thanks.

I expected to need to tune the Antenna, but with SWR at 3+ across all channels, I don't think tuning the length is going to help. I am wondering if the bone head broke off my antenna also cracked the insulation inside the stud when they broke the antenna off.

Since disrupting the ground to the stud improves the SWR, I must have short somewhere. I'll replace the stud first, then try to find a short in the coax ends if the stud does work.

Can anyone tell me how to test for a short in either the stud or the coax. I have a multi-meter, just not real familar with using it to check anything other than voltage.

-wwiifirearms

wwiifirearms

Is it possible to have a short in the Radio?

Using the multi-meter (I think correctly) the outer shielding stays grounded and the antenna lead stays ungrounded (no short), until I plug it into the radio at after which I can detect some ground in the antenna wire.
Is this normal?

SWR still way over 3 with the antenna mount grounded and around 2 when the antenna mount ground is disrupted.

I am stumped, but that isn't always hard to do.

-wwiifirearms

AK4Dave

Hook up your antenna to the mount like you would normally. Then disconnect the coax from the radio. Put your tester on "continuity". Turn on the tester and touch the probes together to see if you hear a tone or a light lights up. Then touch one probe to the center of the coax (hot) connector and the other probe to the outside (ground) of the connector. If you hear a tone, or see a light from the tester when you touch them then you have a short.

wwiifirearms

Thanks. I followed your proceedure.
It does not appear to have a short.

Multi-meter reads 0.930 when probes not touching, and 0.288 with probes touching each other. With one probe on each portion of the coax it still reads 0.930. I think this means no short in coax, mount, or antenna.

So what could it be?

-wwiifirearms

medbender

dude, just tune the antenna. some have a screw on top but most you'd just trim about 1/8'' off at a time. dont forget to put the cap back on before testing. I took about 1/2'' off mine before it was right but that will vary.

AK4Dave

What???........I wouldn't go tellin' somebody to start hacking off his stinger before you know it even needs to be trimmed, because there's no going back after that. How do you know that it doesn't need to be longer? Yes he could try adjusting it but if it reads over 3 all across the band I'd say there's something else going on there.

wwiifirearms......did you try adjusting the stinger at all? Are the swrs better on one end of the band? Remember this.....the lower the frequency the longer the antenna......the higher the freq. the smaller. Try extending the stinger and see what happens, if anything, at least that will tell you if the stinger "may" need to be trimmed. Put it on channel 1, check the swrs, extend the stinger and if the swrs get better at all on channel 1 then the antenna could be too long. But if you extend it all the way out and nothing changes then there indeed is something else wrong. The antenna has to be way too long or way too short (which is unlikely) for there not be any change in swr at all when you adjust it.

Oh, about the radio having a short.....unless you were transmitting when the antenna was broken off it should be fine. You may have to start looking closely at the coax and make sure there are no severe bends in it somehwere. Or, do you have access to another coax? You can try that an see if anything changes. Also make sure your ground is still good.

wwiifirearms

Thanks. Did this test and it is grounded.

Someone mentioned a stinger, what is this?

Right now:
SWR on channel 1 is 2.5
SWR on channel 40 is 3.9

-wwiifirearms

wwiifirearms

Since channel 1 was 2.5 and channel 40 was 3.9, I took off about 3/8" (half of one coil) and now they are 2.9 on channel 1 and 3.3 on channel 40.

Since Channel 1 is getting worse I don't want to keep cutting.

Thanks for the continued help. The nearest CB shop I know of is at least a 90 minute drive each way, so I am try to avoid making a trip. Plus I don't think they are open on the weekend.

-wwiifirearms