CB antenna - single or dual stick? [Archive]

rodster

01-14-2006, 04:44 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by KenP:
Timgco had two on his H2. They were Firestik's (http://www.firestik.com/) I believe. </div></BLOCKQUOTE>

I've seen pictures of his dual setup and as I recall, there was a story about him at the Radio Shack in Moab, which lead me to believe his antennae are the ones linked-to and pictured above (the "pre-tuned" goods).

But I agree, it does sound like bull. Seems to me the radio and quality of ground would affect the tune. Not to mention that maybe over time the tune shifts and calibration is necessary.

Thanks for the link to Firestik. I'm on their site now.

rodster

01-14-2006, 04:54 AM

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.

KenP

01-14-2006, 05:09 AM

Well, two black Firestiks do look good atleast. http://www.elcova.com/infopop/emoticons/icon_wink.gif

rodster

01-14-2006, 05:36 AM

I've read more on the Firestik site and am now officially dangerous. http://www.elcova.com/infopop/emoticons/icon_smile.gif 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.

HummerLV

01-14-2006, 01:02 PM

this is what i have and have had no problems
Firestik®II "FS Series"
40 Channel +, Tunable Tip CB Antenna 2' black
coupled with cobra http://www.cobra.com/index.php?page=shop/flypage&product_id=5&id=1 (http://www.cobra.com/index.php?page=shop/flypage&product_id=5&id=1)

ree

01-14-2006, 04:30 PM

rodster,
I'm no CB expert either, but I went with a single 3' Firestik Firefly that I plan to mount over the driver window like Phil and a couple others have done.

I haven't fully mounted it yet, but I have grounded it to the H2 and hooked it up to my Midland 75-822 (http://midlandradio.com/comersus/store/comersus_viewItem.asp?idProduct=3108) handheld and it made a big difference in reception without even getting it tuned compared to the reception that the handheld got with just it's little 10in whip. I can pick up truckers on the interstate a few miles away with mild visual obstructions like trees. So it seems for my needs a single stick is plenty.

I'm just too lazy to consider dual sticks and the extra tuning.

BTW, if you are in the market for a handheld/mini, I'm really fond of my Midland 75-822. You can pick it up for ~$85 and it comes with three different power kits, one for completely portable battery powered use, one for in car mount with a 12V plug and antenna connector, and one for AC wall outlet+nicad recharging. It's about the same size as the cobra 75.

rodster

01-14-2006, 05:11 PM

Thanks everyone!

It's always great to read the bottom line and specific recommendations.

I bought the Cobra 75WXST in early December. At that time I was in a hurry to have it working so I also bought a magnetic base antenna. The goal now is to have a more effective and permanent setup.

I'll pick up the single Firestik this weekend. Firestik's Firefly is appealing due to its flexibility although I imagine I can get sufficient flex by installing a base spring.

One more question:

I see on Firestik's web site three different coax setups, each with a different type connector on the antenna end. All but one look like one end's connector will need to be cut-off to allow the cable to fit through the roof marker light boot. True? If yes, then do you recommend also buying a replacement connector?

This model cable from Firestik is made for easy routing. If I can find it, this looks like the ticket, yes?

http://www.firestik.com/images/mu-8r18.jpg

Thanks again. I very much appreciate your time and advice.

KenP

01-14-2006, 07:36 PM

<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. http://www.elcova.com/infopop/emoticons/icon_wink.gif

ree

01-14-2006, 09:04 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rodster:
This model cable from Firestik is made for easy routing. If I can find it, this looks like the ticket, yes?

http://www.firestik.com/images/mu-8r18.jpg
</div></BLOCKQUOTE>

Yes. This is what other's have said works (the MU-8R18), and I bought the same on that recommendation. Never having seen the marker light holes first hand, I can't say it will work, but it looks like it will.

I'm sure Phil will know; he seems to know something about everything http://www.elcova.com/infopop/emoticons/icon_wink.gif

I'll semi-hijack the thread and ask others where do you put all the excess coax? I defintely don't need all 18' and Firestik says not to coil it (RF choke). I suppose this means it's got to be spread around the headliner????

ree

01-14-2006, 09:05 PM

BTW rodster,
Here's a very useful prior link that documents the firestik+jeep mount, and even has a parts list on the last page.

http://elcova.com/groupee/forums/a/tpc/f/6706011751/m/3686044512/p/1

rodster

01-14-2006, 09:42 PM

Thanks for the link, Ree. I've been all over that thread a few times.

Took a drive down to Boulder City today to Radio World. What a place! It's a small shop run by a guy who was very patient and answered all my questions.

Snipping one connector is standard stuff. He didn't have the coax like the one pictured above but he did give me the replacement connector. That'll be easy to install since I already have the coax crimper.

I bought a standard issue mount that'll clamp on my Gobi rack. Also and based on Phil's recommendation, I bought a swivel joint (not a spring) to put between the antenna and the base. That'll allow for laying the antenna flat for garage parking and when driving through tall brush.

I ended up with a four foot antenna. The difference in money between it and the shorter models was peanuts but the increase in range is, in the shop owner's opinion, worth it. After hearing his explanation why I have to agree. I don't know if the added length and range will every be necessary but it'll be nice to have if it is.

I also picked up a SWR meter to tune the antenna. It was cheaper to buy the meter ($20) than drive back down to his store for the free tune, which he did offer.

Here's a different take on coax length: The gent at the radio shop (he's been a ham for decades and playing with CBs since Smokey was a bandit) said that length is not critical. He said the coax needs only be as long as it takes to reach the radio. He did advise I have the install nearly finalized before tuning so I expect the coax length will impact that.

Thanks again everyone for all the assistance. I'm off to the garage to install.

CslRkH2

01-14-2006, 10:34 PM

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

01-15-2006, 12:22 AM

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

Very interesting. So how about mounting the antenna in the middle of the the horizontal, left-to-right bar that's just aft of the sunroof? That's where I put mine today (and it damn well better work since I had to scrape powder coat to get a good ground http://www.elcova.com/infopop/emoticons/icon_mad.gif). I ran out of daylight before making the coax run to the interior so I haven't had a chance to test it. Based on what you say, I'd guess my best reception will come from the back, the sides will be even and in front will be the weakest. Agreed?

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">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. </div></BLOCKQUOTE>

I grabbed this off the Firestick site.

About the length: This is a testy subject with many engineering types. They have argued with us on many occasions regarding this matter. They say that if your system is set-up properly that the length of the coax is irrelevant. We agree! However, mobile installations have so many variables that a perfect set-up is the exception, not the rule. One guy has a pick-up and another has a fiberglass motorhome. One wants the antenna on the bumper, another on the hood and a third on the roof. Few people want to drill holes in their vehicle so quality grounds are always a consideration. Because of the imperfect world, we almost always recommend 18' (5.5m) when our products are used. We do so with good reason too! At 18' the voltage curve has dropped back to the zero voltage point where the cable meets the antenna which reduces the reactance within the cable itself (a null cable if you would). It has been our experience that if the antenna location makes it somewhat out of sync with its surroundings, cable lengths that are not multiples of our 18' suggestion adds to the problem. To that, our complaining experts say, "Then the antenna should be moved!" to which we say, "You tell the guy with the $30,000 vehicle that he must drill a hole in his roof so he can use a 9' cable". We solve problems in the best way we can given the boundaries that the customer establishes.

On that note, when you have 18' of coax going to a radio that is only 8' away, what should you do with the other 10'? We recommend that you serpentine it like a skein of yarn so that it is 10-14" long and tie it in the center with a wire tie then tuck it away. Do not roll it up in a tight circle as this can cause it to act like an RF choke, which often times will cause system problems.

If I read that right, it's all about the ground? And if the ground and all other components are good, length is negotiable?

rodster

01-15-2006, 12:24 AM

<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.

rodster

01-15-2006, 01:52 AM

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

I'll semi-hijack the thread and ask others where do you put all the excess coax? I defintely don't need all 18' and Firestik says not to coil it (RF choke). I suppose this means it's got to be spread around the headliner???? </div></BLOCKQUOTE>

Check out the last paragraph of the italicized text above. The answer is there.

ree

01-15-2006, 02:07 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rodster:
Check out the last paragraph of the italicized text above. The answer is there. </div></BLOCKQUOTE>
Thanks. Of course, all I need is more wires up behind the rail under the dash http://www.elcova.com/infopop/emoticons/icon_wink.gif

KenP

01-15-2006, 05:07 AM

Two questions:

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

2) Phil, how did you ground the rack?

rodster

01-15-2006, 05:18 AM

<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?

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">2) Rod http://www.elcova.com/infopop/emoticons/icon_smile.gif , how did you ground the rack? </div></BLOCKQUOTE>

I think it happened when the lights went on the Gobi. I didn't do anything else to ground the rack and I don't think the normal rack install would do it. I checked for continuity between the rack and a known good ground spot and it was 0.00 on the ohmeter.

Dick Renaud

01-15-2006, 06:03 PM

As a HAM since the fifties and a commercial 2-way shop owner for 15 years dealing in low band VHF (39mhz) and CB as well as high band and UHF, here is some info.
If you have a properly grounded vehicle, cable length is not a factor, in fact at low power CB shorter lenghth is an advantage. You are attempting to keep the resistance of the cable balanced with the radio and antenna to get maximume power transfer.
Grounding: Must include grounding the antenna to the roof, if you are using complex mounts with open ground brain from the coax, an additional short length of copper braid, flattened and attached between the antenna ground screwed with star washer into the roof and sealed with silicone or other water tight seal will help. Body ground, you also should ground the body metal under the vehicle to the frame using the copper braid and weather sealed.
Last but not least, ground the negative post of the battery to the frame in the same manner. The regulare vehicle electrical ground is not all that solid and needs this extra solid ground. In all cases wire brush the surface area and clean with alcohol. On more help is to ground the tail pipe to the frame. It can cause electric noise.
Power, it is alway best to run a "home run" positive and negative cable * or 10 gauge from the batter to the radio. If you hook up to any other vehicle electric you will get noise. Vehicle electrical systems have very poor RF suppression. Check with your local sound installer. They always connect direct for noise suppression and heavy power need.
Tuning, the previous post is correct, the antenna must be in use condition when tuned. One thing many people forget when tuneing especially when the mount is over the drivers door, close the door.
One last thought, the Firestick is a great antenna because you can tune it easily and retune it any time you add something to the roof a9lights, bars etc). The rule for antennas is the longer the better. The 4' Firestick is the best comprimise for a low profile, foldable antenna.

In radio, every little thing adds up to major difference in results. You can short cut it if you don't care about the extra distance or clarity.

As a cop and emergency worker for many years I always go the extra step for the added security in that one situation when you REALLY need the extra.

KenP

01-15-2006, 07:57 PM

<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.

rodster

01-15-2006, 08:14 PM

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

01-15-2006, 09:09 PM

There is a difference between Electrical Ground and RF Ground. The VOM reads Electrical Ground. You need more expensive test gear to read RF. The best and cheapest this is to be sure that you have good,Clean (wire brushed or dremmeled), tight physical ground connection between the antenna and the ground surface. Something I forgot in my other post is that you need a good physical ground between the Radio chassis and the vehicle chassis. The can be acheived if you have a large screw on the back of the radio or drill a hole in a clear area of the back plate and, in either case attach a flat copper braid or flat copper strap with stainless steal nut and bolt or replace the chassis screw with stainless screw and stainless star washers. Seal the connections with RTV silicone or Plasti Dip. This seals out moisture and prevents the hardware from working loose. If you don't seal them, check them for tightness monthly. A ground that is not very tight can cause static interference. It may look tight, but tighten it to be sure. The copper strap is the best grounding material because RF travels on the surface of the copper not inside and strap has more surface area. I mentioned tailpipes before. The are a leading cause for noise in ham HF (CB frequencies fall in that range) frequencies. When grounding tailpipes it is best to use a stainless steel pipe strape to secure the ground and use a high temp sealing material.
One other point is to solder all connections, no clippies.
If you want lots more info on mounting and wiring and grounding check this site:
http://www.k0bg.com/ Alan is what is called in HAM an ELMER. That is a very experienced HAM who helps newer HAMs figure it all out. HAMs by nature are experimenters and are always tweeking and seaking better ways to get the most out of the least. I have spent a great deal of time asking ELMERs for advise and Alan is one of the most knowlegeble and acurate ELMERs I have found.

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.

rodster

01-16-2006, 12:07 AM

Thanks for the great info, Dick.

<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 ... </div></BLOCKQUOTE>

I'm all about overkill! Sure, I could have just run the coax under the dash and had a completed, simple install done by now but NO! I saw an opportunity to do things a little differently and hopefully (at least to myself), a little better. Here's the current state of the project. http://www.elcova.com/infopop/emoticons/icon_smile.gif I wonder sometimes if I'll ever outgrow this ...

rodster

01-16-2006, 12:12 AM

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

Under the headliner or under the carpet I guess. </div></BLOCKQUOTE>

I don't know of a reason why either of those wouldn't work. It would be a lot more work.

One thing I learned today: coming down the left A-pillar is a whole lot easier than the right. There's lots of open space under the driver's side of the dash. Not so on the passenger's. http://www.elcova.com/infopop/emoticons/icon_mad.gif

KenP

01-16-2006, 12:32 AM

You might as well install your dream stereo now, too. http://www.elcova.com/infopop/emoticons/icon_wink.gif

CslRkH2

01-16-2006, 01:14 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rodster:
I'd guess my best reception will come from the back, the sides will be even and in front will be the weakest. Agreed?

I grabbed this off the Firestick site.
Because of the imperfect world, we almost always recommend 18' (5.5m) when our products are used. We do so with good reason too! At 18' the voltage curve has dropped back to the zero voltage point where the cable meets the antenna which reduces the reactance within the cable itself (a null cable if you would).
</div></BLOCKQUOTE>

I agree. By placing it in the middle does that make it hard to get to? If your OK with a middle of the roof location, why not mount in the exact middle through the mesh GOBI deck?

Dick R is on the money with the distinction between Electrical Ground and RF ground. BOTH are important in this install. You must have an electrical ground or you will have a SWR reading of 3+. This is bad and can negatively effect your CB Radio. When you are tuning...If the lower CB channels are "worse" than the upper channels then this is an indication of an insufficient ground place (RF ground plane). This info can be found on FireStik.

I used that exact coax cable you had pictured, the mounting location I showed in my pic, and achieved at ~1.7 at channel 1 and a ~1.4 at channel 40. This means I had a little bit of a weak RF ground plane. The closer to the metal H2 roof you can the better (I had better and almost equal readings at 1 & 40 before the GOBI install; I think the few inches of elevation away from the roof caused this change).

CslRkH2

01-16-2006, 01:19 AM

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

In radio, every little thing adds up to major difference in results. You can short cut it if you don't care about the extra distance or clarity.

As a cop and emergency worker for many years I always go the extra step for the added security in that one situation when you REALLY need the extra. </div></BLOCKQUOTE>

Totally agree, all the time you spend tuning will pay off because you will be able to hear and be heard more clearly and from a greater distance.

ree

01-16-2006, 01:31 AM

<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>

Damn, why does every thing have to be more complicated that I thought it was going in http://www.elcova.com/infopop/emoticons/icon_wink.gif

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?

ree

01-16-2006, 01:34 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rodster:
Here's the current state of the project. http://www.elcova.com/infopop/emoticons/icon_smile.gif </div></BLOCKQUOTE>

Ha, ha! Now you get to fuss with those little retainer clips on the bottom of the cup holder tray that slide around when you try to remount the damn thing http://www.elcova.com/infopop/emoticons/icon_wink.gif That alone is enough to keep me from opening up my center console one more time unless it's a national emergency.

KenP

01-16-2006, 03:08 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Carl:
I agree. By placing it in the middle does that make it hard to get to? If your OK with a middle of the roof location, why not mount in the exact middle through the mesh GOBI deck? </div></BLOCKQUOTE>I had mine mounted through the mesh on the driver's side. I ran into two problems. The first being the joint not being long enough to go through the mesh and two thick washers.

The second is I had to use two smaller washers against the mesh so everytime the antenna hit a tree it moved and started loosening by rocking back and forth. You have to use two very wide washers to hold it to the mesh.

rodster

01-16-2006, 03:14 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by CslRkH2:

By placing it in the middle does that make it hard to get to? </div></BLOCKQUOTE>

Nope, and that's one of the reasons I put it where I did -- ease of access. I open the sunroof, reach up, slide up the spring-loaded sleeve that contains the pivot joint and lean the whole thing down.

I considered putting it on the driver's side for easy access but then I wouldn't have the full benefit of the what roof I have now. Plus, it just looks better in the middle. http://www.elcova.com/infopop/emoticons/icon_smile.gif

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">If your OK with a middle of the roof location, why not mount in the exact middle through the mesh GOBI deck? </div></BLOCKQUOTE>

No can do. I carry recovery gear and other stuff up there regularly. I need the rack space.

Appreciate the other input, too, CslRkH2!

Dick Renaud

01-16-2006, 03:16 AM

<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 http://www.elcova.com/infopop/emoticons/icon_wink.gif

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

01-16-2006, 03:20 AM

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

Damn, why does every thing have to be more complicated that I thought it was going in http://www.elcova.com/infopop/emoticons/icon_wink.gif

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> </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.

rodster

01-16-2006, 03:23 AM

Dick -- I believe by "handheld" he's referring to this Cobra unit (http://www.cobra.com/index.php?page=shop/flypage&product_id=5&id=1), which is more of an all-in-one than handheld.

http://www.cobra.com/shop_image/product/6055bdd1808a899fc1267caf68f9141a.jpg

I still have a few questions for you, Dick, but need to get back outside to handle a few more install details. Then I'll finally come in, thaw out, shower and see if I can still form a sentence. If not, I'll be back at it in the morning. Thanks for everyting!

KenP

01-16-2006, 03:27 AM

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

Rod has a PM. http://www.elcova.com/infopop/emoticons/icon_wink.gif

rodster

01-16-2006, 03:47 AM

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

Rod has a PM. http://www.elcova.com/infopop/emoticons/icon_wink.gif </div></BLOCKQUOTE>

And he answered it. http://www.elcova.com/infopop/emoticons/icon_smile.gif

rodster

01-16-2006, 04:31 AM

Progress! http://www.elcova.com/infopop/emoticons/icon_smile.gif

The antenna is on, the coax is run and tomorrow I'll run power and ground, tune and then button everything up. If you own the Cobra unit (and if you care http://www.elcova.com/infopop/emoticons/icon_wink.gif) , you can see where I'm headed. After all this, I better be able to talk to my dad in Florida!

rodster

01-16-2006, 05:41 AM

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

You are attempting to keep the resistance of the cable balanced with the radio and antenna to get maximume power transfer. </div></BLOCKQUOTE>

I hear two possible things here (and I may be way off so bear with me, please):

1. More length = more impedance which = less transmit power?

and/or

2. There is possibly a formula for calculating optimum coax length on a properly grounded vehicle when radio and antenna specs are known?

------

Like Phil said earlier, in the end a basic CB setup will no doubt do more than I ever need it to normally do, i.e., communicate with other moving trucks that are fairly close.

BUT, I'll take your advice and do the extra grounding and homerun power because I fully expect the CB will give way to a ham unit soon. The purpose of that radio will be much broader and maximum performance will absolutely be desired. Plus, even if it's only a CB today, I'd still like to get the most out of it because, well, because I can and I enjoy the tinkering. http://www.elcova.com/infopop/emoticons/icon_smile.gif

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">One last thought, the Firestick is a great antenna because you can tune it easily and retune it any time you add something to the roof a9lights, bars etc). </div></BLOCKQUOTE>

I had a choice between Firestik and Wilson. The shop owner was very high (to say the least) on Wilson so based on his recommendation and my desire for a flex unit, I bought the Wilson Silver Load Flex 4 (http://www.wilsonantenna.com/fg.htm) . Any thoughts on that?

You mentioned the antenna can be retuned when something new is added to the roof ...

When I'm headed off-road, I mount quite a bit of metal recovery gear on the roof rack. Will that effect the tune? If yes, given that I'll most often use the radio when off-road, would you advise I tune with the gear on?

Thanks much, Dick. I'm grateful for your time and input. Same goes for anyone else that wants to chime in!

rodster

01-16-2006, 06:00 AM

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

That alone is enough to keep me from opening up my center console one more time unless it's a national emergency. </div></BLOCKQUOTE>

Now that's funny! http://www.elcova.com/infopop/emoticons/icon_biggrin.gif

Oddly enough, before pulling the center console apart I found one clip under the seat while looking for a renegade lock washer. I didn't know what it was until I pulled the cupholder out. When I did pull it out, I salvaged one clip while another went to China, current address unknown.

I'm thinking two-sided 3M stick-it-like-you-hate-it tape. Eh?

Dick Renaud

01-16-2006, 10:58 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rodster:
Dick -- I believe by "handheld" he's referring to this Cobra unit (http://www.cobra.com/index.php?page=shop/flypage&product_id=5&id=1), which is more of an all-in-one than handheld.

http://www.cobra.com/shop_image/product/6055bdd1808a899fc1267caf68f9141a.jpg

I still have a few questions for you, Dick, but need to get back outside to handle a few more install details. Then I'll finally come in, thaw out, shower and see if I can still form a sentence. If not, I'll be back at it in the morning. Thanks for everyting! </div></BLOCKQUOTE>

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.

Dick Renaud

01-16-2006, 11:23 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rodster:
[QUOTE]Originally posted by Dick Renaud:

You are attempting to keep the resistance of the cable balanced with the radio and antenna to get maximume power transfer. </div></BLOCKQUOTE>

I hear two possible things here (and I may be way off so bear with me, please):

1. More length = more impedance which = less transmit power?

You are close, but impedance should remain constant at 50 ohms. Length = resistance which = heat which = power loss. the more lenth the more loss and at about 4 watts or less output power at best (the 5 watts is input power) you need all you can retain. Also, there is some increase in recieve (mostly in noise reduction) with shorter coax.

I had a choice between Firestik and Wilson. The shop owner was very high (to say the least) on Wilson so based on his recommendation and my desire for a flex unit, I bought the Wilson Silver Load Flex 4 (http://www.wilsonantenna.com/fg.htm) . Any thoughts on that?

Wilson is a good antenna, but generally longer and more difficult to tune. If the additional length is not a problem its fine. I should mention that a flexable antenna changes radiation pattern as it sways back and forth or lays back at high speed. The Firestick is ridgid and holds it pattern better. I would use a spring with a firestick to take minor hits better, but as mentioned earlier, a ridgid antenna on the trail may be damaged. The only antenna that will take the trail is a short rubber antenna and you loose distance with that. A comprimise that we used to use on police vehicles is a Larsen with an NMO mount mounted into the roof with a backer plate. The Larsen is very flexable and with a solid mount will take a lot of abuse as long as it is not hit to close to the base.

You mentioned the antenna can be retuned when something new is added to the roof ...

When I'm headed off-road, I mount quite a bit of metal recovery gear on the roof rack. Will that effect the tune? If yes, given that I'll most often use the radio when off-road, would you advise I tune with the gear on?

Absolutely tune with everything on that you will normally run with. Anything in proximity to the antenna can de-tune it. One addition though, the rack etc should be grounded to the roof with braid. The regular mounts are not a very good ground. Also, any loose body metal ( hood, lift gate etc) should be Bonded (grounded) with braid. Again, refer to Alans web site referenced in my earlier post.

ree

01-16-2006, 11:26 AM

<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 (http://midlandradio.com/comersus/store/comersus_viewItem.asp?idProduct=3108) 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.

Dick Renaud

01-16-2006, 01:23 PM

Portables work ok at short range in a vehicle with an external antenna. The problem is because there is no provision for grounding they do pick up alot of noise on both TX and RX. If you need to go portable it is a comprimise that you must accept. If you can afford it, I would put the Cobra in the vehicle and have the Midland for portable ops. For Ham, I have an ICOM IC-7000 (HF/VHF/UHF) in the vehicle and a Yeasu FT 7r (VHF/UHF) for portable ops. Again, you have to decide what the use will be and what you are willing to accept in distance and quality. The ultimate would be a 100' tower, Beam antenna and rotor with a half acre ground plan and a 1000 watts.

It is really what is practical for you.

ree

01-16-2006, 01:35 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Dick Renaud:
...The ultimate would be a 100' tower... </div></BLOCKQUOTE>

Ken,
Can you do the photochop on this? http://www.elcova.com/infopop/emoticons/icon_smile.gif

Klaus

01-16-2006, 01:44 PM

<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?

Rotary Flyer

01-16-2006, 02:11 PM

If you want some really good info on mobile radios...check out this web site http://forum.worldwidedx.com/ There are some real gurus of mobile radio there!

Dick Renaud

01-16-2006, 04:04 PM

<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+

Dick Renaud

01-16-2006, 04:10 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Rotary Flyer:
If you want some really good info on mobile radios...check out this web site http://forum.worldwidedx.com/ There are some real gurus of mobile radio there! </div></BLOCKQUOTE>

Great site. Here is another one http://www.eham.net/

There are so many out there you can read for ever.

rodster

01-16-2006, 04:48 PM

Great stuff, Dick. Thanks much. And thanks, RF, for the link.

rodster

01-16-2006, 06:49 PM

Suspicious first SWR test ...

The meter instructions say SWR tests are accurate to within 5%.

No tuning done and here's what I got.

CH1 1.1 and a hair.

CH40 1.3.

Almost seems too good to be true. Comments, anyone?

Dick Renaud

01-16-2006, 07:28 PM

Hard to get much better than that. Good work!

Dick Renaud

01-16-2006, 07:43 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Dick Renaud:
Hard to get much better than that. Good work! </div></BLOCKQUOTE>

Check it again when you get the roof loaded with your gear.

rodster

01-16-2006, 07:51 PM

Thanks! I'm pretty pleased right now.

Tested two more times with no gear, then two times with. Still have done no tuning.

ree

01-16-2006, 07:59 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rodster:
Still have done no tuning. </div></BLOCKQUOTE>
Good job. I'm jealous. I just know mines going to be all messed up when I get around to it.

more picts????

rodster

01-16-2006, 08:18 PM

I'll take pics later. The dash is still in pieces.

Not sure at this point if I'm going to do any tuning. Thoughts?

rodster

01-16-2006, 08:46 PM

Antenna ...

rodster

01-16-2006, 08:46 PM

Base ...

rodster

01-16-2006, 08:47 PM

Antenna folded. Still have to decide what to do with the matching wire. Directions say it's only necessary if SWR won't go sub 2.1. Suggestions?

Dick Renaud

01-16-2006, 09:17 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rodster:
I'll take pics later. The dash is still in pieces.

Not sure at this point if I'm going to do any tuning. Thoughts? </div></BLOCKQUOTE>

Considering that it is mounted on the rack and the best match you can get with a solid roof mount is 1 to 1, I would leave it alone and be greatful. Great job and it looks great to.

Dick Renaud

01-16-2006, 09:20 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rodster:
Antenna folded. Still have to decide what to do with the matching wire. Directions say it's only necessary if SWR won't go sub 2.1. Suggestions? </div></BLOCKQUOTE>

You don't need it.

Dick Renaud

01-16-2006, 09:25 PM

You shoud finish by sealing all the connections with clear Plasti Dip including the clamps on the rack. That will keep the contacts dry and tight. The hinge join don't use the Plasti Dip, use dialectric grease and re grease it periodicaly.

rodster

01-16-2006, 09:48 PM

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. http://www.elcova.com/infopop/emoticons/icon_smile.gif

ree

01-16-2006, 10:37 PM

Rodster,
Looks great.

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rodster:
I have a good supply of PlastiDip -- it's a favorite tool, so to speak. </div></BLOCKQUOTE>

Is that some latex fetish thing http://www.elcova.com/infopop/emoticons/icon_biggrin.gif ???

Dick Renaud

01-16-2006, 10:49 PM

<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. http://www.elcova.com/infopop/emoticons/icon_smile.gif </div></BLOCKQUOTE>

The high tech tools are always the best...

CslRkH2

01-17-2006, 12:53 AM

CslRkH2

01-17-2006, 12:56 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by KenP:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Carl:
I agree. By placing it in the middle does that make it hard to get to? If your OK with a middle of the roof location, why not mount in the exact middle through the mesh GOBI deck? </div></BLOCKQUOTE>I had mine mounted through the mesh on the driver's side. I ran into two problems. The first being the joint not being long enough to go through the mesh and two thick washers.

The second is I had to use two smaller washers against the mesh so everytime the antenna hit a tree it moved and started loosening by rocking back and forth. You have to use two very wide washers to hold it to the mesh. </div></BLOCKQUOTE>

Good to know...

Who's Carl? http://www.elcova.com/infopop/emoticons/icon_smile.gif

saturn75

01-21-2006, 03:34 PM

Go with the wilson 5000 one of the best out there.

ree

02-09-2006, 05:06 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rodster:
Thanks! I'm pretty pleased right now.

Tested two more times with no gear, then two times with. Still have done no tuning.
http://elcova.com/groupee/forums/a/ga/ul/9991059251/inlineimg/Y/swr.jpg
</div></BLOCKQUOTE>

Rodster, Dick, anybody else,
I just got mine all hooked up and went outside and tested it. With the antenna up, I got my SWR tuned to:
<table border="1">
<tr><th>Channel</th><th>1</th><th>19</th><th>40</th></tr>
<tr><th>SWR</th><th>1.1</th><th>1 - 1.1</th><th>1.2-1.3</th></tr>
</table>
But for kicks I decided to check it with the antenna folded down and the SWR jumped way up into 3+ range. I didn't expect it to be so bad.

I know that Glenn on this thread (http://elcova.com/groupee/forums/a/tpc/f/6706011751/m/3686044512/p/1) said he had "good range" with the antenna down. But with my SWR so high isn't it bad for the radio to transmit?

Rodster,
Did you check your SWR with the antenna down? If so, what was it?

Dick, anybody else,
I've got a Firefly 3' antenna, it didn't have the little ground wire like some antennas do. I do have a left over eyelet/lug from the mounting plate because I got the plate to ground on the roof rails really well. Should I try inserting this between the antenna and the Valor foldover and then running a wire to the stud above the insulator but below the foldover to improve conductivity? Or will this not help at all.

BTW, once I figure out the handset mount for my Midland, I'll do some picts on a new thread. Even though it's like a lot of other people's mounts, I took a few pictures of the process that I haven't seen elsewhere.

rodster

02-09-2006, 06:18 PM

<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?

ree

02-09-2006, 06:28 PM

I was also guessing that it isn't making good contact when folded down. Hence the idea to directly wire the top portion to the stud.

I don't really expect it to work well when folded down, but I'd like to know that if I do transmit with it down accidentally, I'm not going to be damaging the radio. I'll just try not to do that http://www.elcova.com/infopop/emoticons/icon_smile.gif

rodster

02-09-2006, 07:24 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ree:
I was also guessing that it isn't making good contact when folded down. Hence the idea to directly wire the top portion to the stud.
</div></BLOCKQUOTE>

That extra wire is for ground, yes? My concern about adequate contact isn't about ground but rather, the signal itself.

This one is way over my head so hopefully Dick will have something.

shhrtbs

02-09-2006, 07:31 PM

if it's folded down, you're reflecting your transmit signal off the roof and right back into the antenna. the swr is telling you how much reflected signal is coming back to your transmitter. a swr reading of 1.0 is perfect, and hardly achieved. most standard commercial broadcasters shoot for a reading of 1.5 or better. anytime you broadcast with your antenna folded flat, you're going to be reflecting that signal back into your transmitter. it's not good for it, but a lot of today's cbs are pretty bulletproof, it shouldn't hurt it unless you keep the transmitter keyed for a long time. it will work better if you put it up though.

Dick Renaud

02-09-2006, 07:41 PM

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.