"Secret" CB antenna for automobile
Jenkins, David F.
I'm looking at an ad for a "secret/hidden" mobile CB antenna. It looks
like a little black box that bolts to the frame or something--costs $27.
If it works, it would be great--no more car wash problems, low-roofed
parking garage problems, etc.
Can anyone tell me if these devices really work? This would be for my
wife's car. She really only wants the CB for standby, emergency use--she
doesn't do a lot of idel chit-chatting.
Anyone?
John F. Woods
>I'm looking at an ad for a "secret/hidden" mobile CB antenna. It looks
>like a little black box that bolts to the frame or something--costs $27.
Work? Maybe, though I think I doubt it. Work well? Absolutely not.
An antenna seriously shorter than a half wavelength (or quarter wavelength
for a "ground plane" antenna) is just not going to be as effective at
intercepting RF as a half-wavelength antenna; losses in loading networks
that are used to transform the impedance of a short antenna to something a
typical solid-state radio can deal with only make things worse. A half-
wavelength at CB frequencies is 5.5 meters (18 feet); hence, loaded whips
perform more poorly than full-size dipoles or base-station ground-planes;
"cellular look" CB antennas that are 12" long are much worse than that; and
a four-inch box is, well, substantially shorter than that.
If you're real lucky, it's a plastic box with a 5W 50ohm resistor, which is
still expensive for a dummy load at $27. I bet it's not even that useful.
(Unless, of course, it's actually a motor that can retract and extend an
actually-useful antenna when needed; that's a different animal entirely.)
WG-12 Ralph E. Milbee Mr
: I'm looking at an ad for a "secret/hidden" mobile CB antenna. It looks
: Anyone?
David,
I just happen to have one of the little items you are looking for. It
is about 10 years old still works as good as it ever did and is in
like new cond. SWR factors are good (1.1-1.5:1 in center band (chans
11-25) but climb to almost 2.0:1 on fringes. Good for chan 19 etc.
I will sell it to you for $25.00 shipped free. Let me know.
Home 912-923-7952 or E-mail to rmi...@wrdis01.af.mil
Bruce Siski
: I'm looking at an ad for a "secret/hidden" mobile CB antenna. It looks
: like a little black box that bolts to the frame or something--costs $27.
Antenna Specialists, Inc. makes just what you're looking for. It's a
small box about 4" x 4" that you plug your regular AM/FM antenna into,
then connect to the CB. You tune up the box to get the best SWR by
adjusting two screws. It works remarkably well, my father bought one
about a year ago. The only problem is the price, about $50 last time I
checked, if you want their address, I can dig it up for you...
--
Bruce A. Siski * The biggest man you ever did see
Southeast Georgia * was once a baby...
tr...@SantaFe.Edu * -- Bob Marley
Dennis Henderson
Then I'll descibe what is working well for me. There is hope....
>I'm looking at an ad for a "secret/hidden" mobile CB antenna. It looks
>like a little black box that bolts to the frame or something--costs $27.
Probably junk. Save your $ and don't buy one.
A. I tried a matchbox/spliter for an am-fm-cb combination antenna with my
regular car antenna (~3 foot telescopic). It wouldn't load up-SWR too high.
This was one of the better splitters that includes adjustment pots for the CB
side and for the am-fm side. Some splitters have no adjustments.
Useless.
B. I added an external cb antenna tuner to setup A. I could get the match
within reason but it worked poorly, even on receive.
Not worth it.
C. The J.C. Whitney motorized am-fm-cb combination antenna was pure junk.
It didn't have a loading coil in the mast at all.
Cheap, crap, ripoff. I returned it.
D. The shorty am-fm-cb combo antennas that are basically ~18" black flexible
antennas are probably too short to be very good. No personal experience.
Anyone tried one?
E. Radio Shack sells a combo antenna. No personal experience.
I wonder if it is very good as the loading coil is below the mount point.
Anyone tried one?
F. I hear the through-the-glass cellphone look-alikes are poor as well.
The element is just too short.
G. There used to be various motorized combo antennas around in the 70's and
80's. My dad had one that worked OK. It had a loading coil and tunable tip just
like the Harada's I use successfully.
The WINNER:
-----------
I've had good success with Harada brand am-fm-cb combination antennas. I have a
fixed mast and a non-motorized telescopic unit. These are ~42 inche units with
a thin loading coil (no wider than the rest of the antenna-gray in color in
both cases) and a small tunable tip. This almost looks like a normal car antenna,
It is just a bit thicker and taller than a stock am-fm antenna.
H. I bought the fixed mast for my Camaro. I grafted it onto the cable and mount
for the normal car antenna. I did this as it required some real tricks to
get at the antenna mount on the car to remove and replace. This setup works much better than I thought it would. I realize the stock cable to the car antenna is
75 rather than 50 ohms but it works. I am quite happy with this for my casual use.
I am impressed.
I. I bought the non-motorized telescopic unit for my wife's car. It works OK but
I don't have much experience with it. You can push back into the fender by hand.
I bought mine from J.C. Whitney but they no longer carry it. I couldn't get
away with using the stock 75 ohm lead-in cable on this car as it the antenna is
on the rear trunk and the cable is just too long. I had to install the 75 ohm
"extender" cable I bought with the combo antenna.
I think JC Whitney still sells the fixed mast Harada's. Anyone know? They look
like Haradas in the catalog. I bought the Harada locally for $50. JCW
wants $25 for theirs. Thinking of buying one for my van so I can use the existing
CB mount for a ham antenna.
Note: I have concluded a good combo antenna must have a loading coil in the
element and a tunable tip. Also the splitter must have an adjustment for CB
and an adjustment for am-fm. You will need an SWR meter to setup this type of
antenna.
Overall: Harada brand combo antennas work quite well on my two cars. They are
not skip-shooting, big strappin' setups but they do work fine for casual up-and-down-the-road CB.
...Dennis Henderson, Unit 289, N6TTW, dennis.h...@sun.com