CB antenna - single or dual stick?

[rodster]

Dick -- Glad to see you spotted this thread. I was hoping you would.

I have a few questions in response to your post but will start with one for now ...

I gather from reading between your lines that a zero reading on the ohmeter does not necessarily equal a good ground. If that's true, is there a better way to test the ground for quality?

[Dick Renaud]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ree:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Dick Renaud:
...
...
...
...
Al this may be a bit of over kill for raw CB, but I have had CBs in many diffent vehicles and building and have found that with a few simple
steps you can get a lot more from your equipment. </div></BLOCKQUOTE>

A handheld was not intended to be used in a vehicle and if it is you don't ground it, you make sure that the external antenna has a good ground plane and if you use a 12 volt lighter plug for power find one with an RF filter in line. Most HAM hand helds offer these. Hand helds and vehicles are really not compatable.
I use an Yeasu 7R VHF hand held and mag antenna for use with rental vehicles etc. It works good with VHF repeaters, but CB is a different animal and much more prone to noise in the reciever and poor transmit power and SWR. It is a big comprimise, but better than nothing.

Damn, why does every thing have to be more complicated that I thought it was going in

Dick, thanks for all this good info. Got a follow up question on the CB ground, though. With a mini handheld, where the whole thing fits in the palm of your hand, grounding the radio chassis doesn't seem to make a lot of sense. It's not real practical to attach a ground strap to the back of it. So this just limits the potential of these small radios right? </div></BLOCKQUOTE>

[Dick Renaud]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Klaus:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Dick Renaud:
I have an ICOM IC-7000 (HF/VHF/UHF) in the vehicle </div></BLOCKQUOTE>

Very nice! I'm thinking of getting into ham radio. Hopefully, the 7000 will get cheaper in the future.

Do you have it in the H2? </div></BLOCKQUOTE>

It is partially installed in my 06 H2. I have everything pulled apart right now. Doing bonding and many other installs. Will be ready in a month or so depending on how side tracked I get with my PI case load.

The 7000 has a few issues that will be worked out, but it is one nice rig. It has the best ears of any mobile I have ever seen. Needs lots of tuning because of all the filters and bells and whistles but worth it. I have worked Africa, China, Japan and New Zealand HF from my driveway North west of Detroit without all the grounding finished. I am running HF with an autotuner and an 8' whip spring and ball on the drivers rear quarterpanel. VHF/UHF dual band 16" rubber antenna centered in the roof between the sunroof and the rear extreme light bar.
I am installing a dual alternator to run a battery in the back for the radio. I am using the seperation kit so I just have the control head on the dash and the small radio pack in in back by the tuner and antenna. *' of coax between the radio and tuner and 4" of bare wire between the tuner and the whip. The VHF/UHF has about 6' of coax to the roof antenna.

The price will come down slightly when Yeasu comes out with there multi band answer to the 7000. probably to about 1100+

[KenP]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rodster:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">1) Has anyone run the coax through the REAR marker? </div></BLOCKQUOTE>

Blasphemy!

Interesting idea. How would you get to the front? </div></BLOCKQUOTE>Under the headliner or under the carpet I guess.

[Dick Renaud]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rodster:
Thanks again, Dick. I'll snip the matching wire, leave the tuning alone and seal the connections. I have a good supply of PlastiDip -- it's a favorite tool, so to speak.

And speaking of tools, I used quite a few on this job but two came in handy more times than I can count: a three foot piece of string and a long, leftover DQ plastic spoon. </div></BLOCKQUOTE>

The high tech tools are always the best...

[KenP]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PhilD:
I'm falling back on what I learned in school now (which was some time ago), but if I recall correctly, antenna size is related to wavelength, the closer you get to a full wavelength the better it will work. So a 1/2 wave antenna would generally work better than a 1/4 wave, etc , etc. </div></BLOCKQUOTE>I used to tell my dates the samething.

[rodster]

I've read more on the Firestik site and am now officially dangerous. New question ...

I see their antennae range in length and watts rating. A 2 foot antenna is rated at 300 watts while a 5 foot antenna is rated at 1000.

If a CB radio transmits a much lower wattage (4 watts, I think), why buy anything over 2' since it's good to 300? Maybe the power rating is meaningless to a non-amplified radio but height is always good regardless of max transmit power?

This is way too much thinking for a Friday night.

[CslRkH2]

You want a large ground plane for the Antenna to work best. Interestingl your great reception will be from the antenna toward the side with the most metal. So if you mount it in the rear passenger, your best reception will be forward to the driver which would be optimal for Interstate Highways. The dual setup in the middle of the roof would provide good reception front and back straight ahead.

Everyone I;ve talked to and the websites like FireStik state yo need 18' coax length. I'm not sure that guy you spoke with was correct in this instance.

The wattage is irrelant I think because the CB's only transmit at 2-5 watts.

When you use your meter to tune the antenna, make sure to put any caps on the end of the antenna on for each measurement. The presence of the caps changes the readings. Yes your antenna needs to be in its final location before youi start tuning.

I bought the Swival with the Spring and it seems work good.

[rodster]

You guys are too funny.

But since this thread isn't ready to die a dignified death ...

Radio Shack has a Fiberglass Twin Trucker CB Antenna Kit (48" each) that they say are "precision tuned at the factory" and don't require further adjustments.

I thought the purpose of tuning was to match the antenna to the radio. No?

Are these the dual antennae you guys have?

[rodster]

This is interesting. From the Firestik page about the dual setup:

Co-phased (or dual) antennas are normally chosen for use by vehicle owners that spend much of their time on the interstate highways. Dual antenna systems create a transmission pattern that has increased field strength directly in front and behind the vehicle. This is especially helpful on vehicles pulling large trailers that tend to shield the antennas radiated energy in one or more directions. Co-phase antenna systems are also useful on vehicles that are lacking in ground plane (composite materials, etc.) as they use the magnetic field from one another as the RF field counterpoise. However, to work properly the antenna mounts MUST have a good chassis ground and the antennas MUST have unobstructed line-of-site between the top 50% or more of the antennas overall length.

There is also much talk regarding the spacing between the antennas. Many people believe that dual antennas will not work unless they are spaced 1/4 wave length (approx 9ft) apart. While this may be true to the nth degree, it does not mean that they will not work with lesser spacing. The spacing will have some effect on the radiation pattern but short of testing every installation and weighing the results against a 9ft spaced installation on the same vehicle, it cannot be assumed that the spacing is better or worse for performance on that particular vehicle. We have seen satisfactory results with antennas spaced as close as 5ft apart.

And don't forget ... ALL antennas, regardless of style or manufacturer, MUST be tuned after installation on the vehicle. Transmitting antennas are not "plug-n-play" devices.

[Dick Renaud]

I would need to use my Taser on her to sell that program.

[Dick Renaud]

ree,
I have been gone working on a case.

The high SWR is to be expected with the antenna folded down. The radiation pattern of an antenna is supposed to be a figure 8 if the antenna is in proper relation to the ground plane (roof) assuming it is centered on the roof. With the off center mount it will be a lop sided figure 8 with directional characteristics toward the vehicle body mass. If the antenna is moved toward the back the lobe will radiate toward the front passenger side. In reality the pattern of the stick type mobile antenna is more circular with a bulge toward the dominant body mass of the vehicle. When you lay the antenna down most of the pattern goes into the roof with some reflection. You can get some very limited short range transmit and receive. As far as damage to the radio, the final transistors may experience damage if you transmit for long periods of time, but CB radios are very low power (less than 4 watts out for 5 watts into the final) so damage may or may not occure. Never use a linear amplifier with that SWR. Not only is it illegal, but it could cause major damage to the linear. The only antenna that will operate in a down position with any acceptable SWR is a full length whip mounted on a ball and spring tied down to the gutter with an insulated clip. This type of antenna still needs a tuner between the radio and the antenna to have acceptable SWR.
All HAMS and Military communications on vehicles that tie down the antenna use tuners. CBers have gotten away with no tuner because of low power, but have SWR of 3:1 to 5:1 or greater.

[dochummer]

noob!

[rodster]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by PhilD:
It isn't critical to have 18' or so of cable, but if you don't then I wouldn't bother tuning it either. The 18' is get you up to a higher wavelength fractional. </div></BLOCKQUOTE>

Well now that's a techno-furball of a different color right there. I did buy an 18' cable so to be safe, I'll use it and "serpentine" it like Firestik recommends.

[Klaus]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Dick Renaud:
I have an ICOM IC-7000 (HF/VHF/UHF) in the vehicle </div></BLOCKQUOTE>

Very nice! I'm thinking of getting into ham radio. Hopefully, the 7000 will get cheaper in the future.

Do you have it in the H2?

[ree]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Dick Renaud:
If he is talking about the Cobra 75 it is not a handheld(portable)I am refering to, it is considered a remote head even though the controls are in the mic. If he is talking about the Cobra 75 the small radio pack that mounts under the dash should be chassis grounded and can be grounded with a strap from the mounting screws if it is not mounted to solid chassis metal. </div></BLOCKQUOTE>

Sounds like there's a decent solution for the Cobra. I went with the Midland 75-822 so I could have true portability in one unit. Instead of a little box like the cobra for wiring it in, it's only got a slide on adapter that has tails for a 12V power jack and the coax. So I guess I don't get a good ground. If it's an issue, I can upgrade the CB to a non-portable.

[KenP]

He may be referring to the Midlands unit, also. That is truely All-in-One.

Rod has a PM.

[ree]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Dick Renaud:
ree,
I have been gone working on a case.
</div></BLOCKQUOTE>
You bastard! I've been sitting around for 2 and half hours waiting for your free advice and your stupid excuse is that "I was working." You're so selfish

Thanks guys for the explanations. I feel better about my CB-newbie install now.

[rodster]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ree:

Rodster,
Did you check your SWR with the antenna down? If so, what was it? </div></BLOCKQUOTE>

Sorry to say, no I didn't.

According to everything I read, you should be concerned with the 3+ reading. Hopefully Dick will see this and offer advice.

A half-baked idea: Given the huge leap in numbers, I wonder if your swivel mount is losing contact when folded?

And FWIW, the tuner instructions said to take readings in an open area. With the antenna next to the roof you're not in an open area, yes?

[KenP]

Two questions:

1) Has anyone run the coax through the REAR marker?

2) Phil, how did you ground the rack?