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Can't get SWR on 102 whip below 2.0:1

SWR on whip

In the late '70s and early '80s a friend and I partnered a business selling and installing CBs and antennas. We sold and installed probably fifty 102" whips on springs. Common in the NE, most installations were on back bumpers. Long coax trips.

I'm betting we had fewer than 10% match better than 2:1 and it got worse with 40 channel. I used the things on my 4WDs and I don't recall worrying about it. I ran legal power radios with SSB and performace in those Allegheny Mountains was spectacular.

With your antenna in the vehicle center, your radiation pattern should be much less directional than mine were from the extreme rear. I would take seriously all the advice about grounding and connecting all the parts of the bed and cab, and I'd run the power from the battery and the ground to something substantial under the hood. (In the old days we usually grounded to one of the bolts holding down the voltage regualtor or fuse box.)

Do everyting you can to keep water out of the connectors and coax. That may mean "monkey poo" or some such "putty" sealer around the connectors. If you've already gotten the coax system full of water, swap it out and protect the new stuff.

If you're within the legal power envelope you may be over-thinking it. Attention to the simple, basic details seems to yield the biggest gains.

Just MHO.
 
SWR on whip

Another quick point/question I have wanted to bring up for a long time and this may be the time and place.

When your check the SWR on a mobile, have any of you ever considered the immediate environment when you check it? I'm talking about buildings, fences, towers, light poles, power lines, a sea of other vehicles?

We had other guys check SWR INSIDE garages and wondered why it was so high. Same thing for packed WallyWorld or workplace parking lots full of other cars. Lot's of weird readings in crowded parking lots an along chain link fence lines.

My own situation at my home right now is messy because I have high voltage power lines running right over my driveway. I try to measue my mobile's 2M/70 cm antenna there and the SWR is astronomical. I drive it out to a remote public park out in the sticks and it's nicely around 1.4.

CB used to do that. My partner had his home on land way out in the country and we liked to do the measurements out there when we could.

Anyone else ever see similar results?

(BTW - laugh if you want - but sometimes at night I would park my truck on a crossing over the unused tracks of a remote industrial RR siding and use the sideband. I could pound and pull signals up and down the Allegany River valley up to 40 miles! At times it out-performed my base's omni. Sometimes some serious DX on Sunday mornings just after sunrise. A lot of times at night I'd have with me some young lady who may have indicated some interest in CB technology and of course we would pay keen interest ONLY to CBing! It's a Country Boy thing I think...)
 
Thinking one of these will be perfect for bonding the matching coil to the system. Better than drilling and tapping the connector.

unnamed.jpg

I wonder how many people think this is an effective way to ground a system, and how many people list them as "lightning arrestors", they are "static discharge couplers" only. MAY help prevent a strike but offers no protection from a direct or nearby strike. But perfect for connecting a matching coil.
If you use these in system that has a center fed dipole of any sort or any antenna with one of the elements connected to the shield, the ground wire will become part of the antenna, with the exception of maybe putting a inductance coil near to the connector to prevent that, and it will still discharge static buildup, but, will probably not protect in the event of a direct strike, but possibly a nearby strike, but don't take my word for it.
 
KF5FUR said:
View attachment 5751

I wonder how many people think this is an effective way to ground a system, and how many people list them as "lightning arrestors", they are "static discharge couplers" only. MAY help prevent a strike but offers no protection from a direct or nearby strike. But perfect for connecting a matching coil.
If you use these in system that has a center fed dipole of any sort or any antenna with one of the elements connected to the shield, the ground wire will become part of the antenna, with the exception of maybe putting a inductance coil near to the connector to prevent that, and it will still discharge static buildup, but, will probably not protect in the event of a direct strike, but possibly a nearby strike, but don't take my word for it.
Click to expand...

I have 2 of those....bought them thru Sparkys...yes they are listed as "lightning arrestors"....so they're not eh? I have one on my base station antenna now, I was going to go get some 12 ga wire to attach to it and then drive a ground stake in the soil. Should I not bother............?????????
 
Turbo T said:
I have 2 of those....bought them thru Sparkys...yes they are listed as "lightning arrestors"....so they're not eh? I have one on my base station antenna now, I was going to go get some 12 ga wire to attach to it and then drive a ground stake in the soil. Should I not bother............?????????
Click to expand...

I would keep it if it's all you have, it prevents static build up on your antenna therefore reducing the likelihood of a direct strike. If I am correct a gas discharge arrestor would be better, but even those may not protect against a direct hit, virtually nothing can for just double digit costs. A lightning strike shunt system costs more than anyone wants to spend unless they are a commercial broadcaster. It is very likely that many of us have been watching TV and not even known that the station tower was hit. They can keep on transmitting through it. I would like to find a way to cobble up a system that can do that for me, but I don't transmit in a storm anyway, so just to completely shunt all lightning into the ground. It all has to do with resistance in the appropriate path.

So definitely keep using it and ground it good, in fact bury the ground rod (minimum length 8ft) 1ft under the ground, a lot of lightning rod installers bury the rod 2ft. Use #10 solid copper wire and a good thick (just not thin and cheaply made) lug to fasten the wire to the rod, and hopefully you have a solder type ground connector with the static discharger and not a crimp. Solder the wire well to it.
I know I already said this but it is important: If you use these in system that has a center fed dipole of any sort or any antenna with one of the elements connected to the shield, the ground wire will become part of the antenna, with the exception of putting a inductance coil near to the connector to prevent that, and it will discharge static buildup.
Not sure as to the dimensions of the coil but a matching coil for 50 Ohm systems is 1:1 or square dimensions, 1" diameter, 1" tall. Like K0BG says, 14 gauge is adequate, but make sure its rigid enough to keep its shape and is insulated in some way so it will not short on its self and raise your SWR.
With enough tool and or strength and ground wire may be able to be shaped so there are not more splice connections then necessary. If the wire is a bit to flexible I would hot glue the hell outta it or something like that.
 
I know this is a little off subject but its related in a way. I got my Radio in my truck finally and the power wired, it started raining so I just slapped the ground to the negative terminal of the battery. The proper mounting is within close proximity of the battery but to the body on its own, not with any other groundings and I would keep it away from grounding straps to, but that's just me. Hooked one wire wound antenna from the co-phased setup I abandoned on a camera tripod away from the truck via a crappy R Shack 75 Ohm cable (no I didn't dare transmit, what do you think I am, an idiot?) I would be if I did with all I know about that stuff there. Just wanted to see if I could hear more than I was in the house with it. I did, all 40 channels were busy, many distant callers, even heard Rhode Island, Jamaica, Wyoming, and Mexico, maybe had to do with the cloud cover, IDK I don't know a whole lot about signal skip yet. But I turned on the truck and much to my suspicion, low and behold, Ignition and Injector noise and loud to. The ANL/NB function suppressed it to a point and for the most part, but when I turn the AC fan to speed 3 and 4 it is terrible even with suppression. I hope once I properly ground the radio, and install my whip and get it matched it will be better. (hopefully I won't have to clip it, :censored: I also don't wanna fool with the nub at the top, or having to buy more crap like a corona ball, I reached my spending limit on this project $45 ago.)

CBpowerconnections.png

I know I used red wire for the negative, I didn't feel like paying double the money to get another color. But there ya go the pic says it all.

One other thing, and I feel kinda dumb for asking this, idk why, but I accidentally turned on the CB for like 3 seconds to take a pic of its install with no cable attached, will it be ok? My rule is never turn it on without a cable and antenna attached, I know elementary rule. That is actually the first time time I've done that, that is why I am so concerned, also it is brand spankin new! (& 100 bucks)

PS- I noticed my battery doesn't have a negative to body cable, every other Ive seen does, that neg cable just goes into the dark un-viewable labyrinth of the engine compartment. It's a 03' Ford F-150 V6 if anyone knows, can I add one?
 
Last edited:
KF5FUR said:
I would keep it if it's all you have, it prevents static build up on your antenna therefore reducing the likelihood of a direct strike. If I am correct a gas discharge arrestor would be better, but even those may not protect against a direct hit, virtually nothing can for just double digit costs. A lightning strike shunt system costs more than anyone wants to spend unless they are a commercial broadcaster. It is very likely that many of us have been watching TV and not even known that the station tower was hit. They can keep on transmitting through it. I would like to find a way to cobble up a system that can do that for me, but I don't transmit in a storm anyway, so just to completely shunt all lightning into the ground. It all has to do with resistance in the appropriate path.

So definitely keep using it and ground it good, in fact bury the ground rod (minimum length 8ft) 1ft under the ground, a lot of lightning rod installers bury the rod 2ft. Use #10 solid copper wire and a good thick (just not thin and cheaply made) lug to fasten the wire to the rod, and hopefully you have a solder type ground connector with the static discharger and not a crimp. Solder the wire well to it.
I know I already said this but it is important: If you use these in system that has a center fed dipole of any sort or any antenna with one of the elements connected to the shield, the ground wire will become part of the antenna, with the exception of putting a inductance coil near to the connector to prevent that, and it will discharge static buildup.
Not sure as to the dimensions of the coil but a matching coil for 50 Ohm systems is 1:1 or square dimensions, 1" diameter, 1" tall. Like K0BG says, 14 gauge is adequate, but make sure its rigid enough to keep its shape and is insulated in some way so it will not short on its self and raise your SWR.
With enough tool and or strength and ground wire may be able to be shaped so there are not more splice connections then necessary. If the wire is a bit to flexible I would hot glue the hell outta it or something like that.
Click to expand...

I know earlier I posted this, but I have typed up a page on lightning protection in greater detail here http://www.worldwidedx.com/installa...ion-about-lighting-protection.html#post322346
 
First, that cable connected to that negative battery terminal very definitively goes to a ground point. If it didn't, it wouldn't power the vehicle. Connecting a radio ground to that negative battery terminal is fine, there's no harm in it at all. If you want to make that connection there, it's fine. If not, then any point on the vehicle that does make connection to that negative post will supply power to the radio (actually, a return path to the battery).
Will turning a radio on with no connection to power harm it? Nope. Will turning a powered radio on with no antenna connected harm it? Nope, just don't transmit with out an antenna!
- 'Doc
 
Swrs on whip antinna

may you could wax or polish the antinna to make the rf get off to a good start and not fall back down to the coax jack.. I wax my whips and the do good for me !
 
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W5LZ said:
First, that cable connected to that negative battery terminal very definitively goes to a ground point. If it didn't, it wouldn't power the vehicle. Connecting a radio ground to that negative battery terminal is fine, there's no harm in it at all. If you want to make that connection there, it's fine. If not, then any point on the vehicle that does make connection to that negative post will supply power to the radio (actually, a return path to the battery).
Will turning a radio on with no connection to power harm it? Nope. Will turning a powered radio on with no antenna connected harm it? Nope, just don't transmit with out an antenna!
- 'Doc
Click to expand...

I actually remembered on a lot of Fords the positive and negative cables go to to the other side of the compartment and connects to the power distribution and master fuse box. Also if I remember correctly both cables are fused with 80 amp maxi fuses. Also the positive cable has a 80 amp fuseable link before that. I just remember all the vehicles before that have had a separate smaller gauge cable coming from the neg terminal directly to the body.

BTW I hope he is kidding :LOL:
Jerry Mcgraw-
"may you could wax or polish the antinna to make the rf get off to a good start and not fall back down to the coax jack.. I wax my whips and the do good for me !"
 
Radio installed with whip

Well I finally got everything installed and running. According to my radio diagnostic, power output and antenna passed. Also according to my radio's meter the SWR is around 1:1-1.1:1 on all channels. I have a feeling the DC ground matching coil had something to do with it and that's all before I even turned the calibration knob, I went ahead and calibrated it properly. Called break and got a good report from 3 miles, from his reply it sounded as if I was very near him. Also my ignition/injector/AC fan motor noise problem is completely gone and I can use the radio while traveling down the highway with ANL and NB off. Possibly because that I moved the negative wire to the body and off the battery or the matching coil or both. The 102" whip looks fantastic on my F-150, but boy does that thing lean back at 70! (is that ok?) Also I got a static discharger (or marketed as a lightning arrestor, which its not) and built a ground strap and ran it between the tap point on the discharger and the body nearby. The matching coil is also grounded on the body as well. I drilled and taped a hole in the stud nut to attach the coil to it close to the bottom near the bracket of the antenna. My wife left the camera at my parents house so when I get that back I will definitely post pics of the install asap.

Another thing I realize that I have not had a antenna analyzer on it yet to check its accurate SWR, resonance, and true wattage output, but I will, I missed my Ham club meeting today so I couldn't do it. The antenna is 107"-11/16 and the tip is 12ft 9in off the ground, center mounted behind cab (about 5in from) with less than a 1/4 of its length behind the rear glass.
 
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W5LZ said:
Connecting a radio ground to that negative battery terminal is fine, there's no harm in it at all.
- 'Doc
Click to expand...
I just wanted to expand on this,
Ok... this is right but... When I was testing my radio, keep in mind the test antenna was not touching the truck. So the RFI noise was coming through the power wiring. The wire being hooked to the battery terminal was making a ground loop, by fastening the wire to the body it provided an independent ground with no ability for anything to loop through the radio. This also protects the radio in the event anything shorts out and prevent a search for a ground through your radio. With the conductor of the antenna DC grounded also further suppresses RFI, the matching coil I suppose also acts as a filter, RF cannot travel through it in either direction, only DC current. I imagine some may think that, that is a direct short, which it is a short but not a "direct" one, there is a lot of circuitry involved between the power input of the radio and the RF output.
 

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