Buyer Beware
I have read all the reviews and I am wondering if they are about the
same antenna I purchased. I bought the Cobra junior antenna and
followed the directions for installation. The antenna is 50ft in the
air in a flat top configuration. When I hooked it up to my radio, it
would not tune on segments of certain bands, most noticeably 75/80. I
called Joe to get some help and was told that my radio, which has a
built in tuner would not accept more than a certain level of SWR and
was told to trim the twinlead back 19 feet. I did and while some of the
problem was solved, I continued to have problems on 75/80. I emailed
Joe to ask for further assistance and was told that the next step was
to buy a tuner extender (price $60). Not the answer I wanted to hear.
If in fact this kind of problem exists with radios that have built in
tuners, prospective buyers should know that in advance. For the cost of
the antenna and now the tuner extender, I could have bought a better
antenna, which is what I intend to do. I am not pleased with this
antenna and would not recommend it especially to someone who has a
radio with a built in tuner and intends to use it. Additionaly, the
performance on 40 seems to be very good. It seems to under perform on
20. Can't tell on 75/80 because I can't tune the band.

KC2GWK

On 8 Jun 2006 05:42:37 -0700, wrote:

Buyer Beware

Hmmm.

same antenna I purchased. I bought the Cobra junior antenna and
followed the directions for installation. The antenna is 50ft in the
air in a flat top configuration. When I hooked it up to my radio, it
would not tune on segments of certain bands, most noticeably 75/80. I
called Joe to get some help and was told that my radio, which has a
built in tuner would not accept more than a certain level of SWR and
was told to trim the twinlead back 19 feet. I did and while some of the
problem was solved, I continued to have problems on 75/80. I emailed
Joe to ask for further assistance and was told that the next step was
to buy a tuner extender (price $60). Not the answer I wanted to hear.
If in fact this kind of problem exists with radios that have built in
tuners, prospective buyers should know that in advance. For the cost of
the antenna and now the tuner extender, I could have bought a better
antenna, which is what I intend to do. I am not pleased with this
antenna and would not recommend it especially to someone who has a
radio with a built in tuner and intends to use it. Additionaly, the
performance on 40 seems to be very good. It seems to under perform on
20. Can't tell on 75/80 because I can't tune the band.

That all seems pretty reasonable though the explanation that the
"built in tuner would not accept more than a certain level of SWR" is
not a good way to express the limits of internal tuners, but it is an
explanation that would appeal to those with lesser knowledge.

Well, it looks like you have learned something that many of us know,
that the internal tuner in most radios has quite limited range and is
really for minor trimming of loads to enable the radio to develop
rated power (not to mention poor efficiency on the lowest bands).

Joe advertises honestly that the antenna will need a tuner for
operation on any frequency, perhaps he needs to spell out that what
manufacturers fit into a corner of a transceiver may not be up to the
task.

Frankly, I am wondering why your beef isn't equally with the
transceiver manufacturer for deceiving you with a tuner that isn't up
to the task.

I wonder what "better antenna" you have in mind? The short multiband
HF antenna that has low SWR(50) on all bands (since you have an issue
with tuners) and good performance is the holy grail of HF amateurs
that will provide you with challenge for the years ahead.

To some extent, the residual technical content in amateur radio is
mating up system components that are compatible to form a working
station.

Owen
--

No antenna will work across the full 75/80 meter band with low enough VSWR to
accommodate all radios. REASON: the bandwidth range +/- 13.3% centered on 3750
KHz to the band edges is excessive. If you cut the antenna for 3.9 MHz it most
likely will not load up well below 3.7 MHz. A tuner is required!! PERIOD.

For comparison, the bandwidth range on 20 meters centered on 14.175 is only +/- 2.4%

Don't jump on condemning the antenna too soon. Do some more research and ask
more questions regarding 75/80 meters broadband antennas and what "broadband" means.

/s/ DD, W1MCE

wrote:

Buyer Beware
I have read all the reviews and I am wondering if they are about the
same antenna I purchased. I bought the Cobra junior antenna and
followed the directions for installation. The antenna is 50ft in the
air in a flat top configuration. When I hooked it up to my radio, it
would not tune on segments of certain bands, most noticeably 75/80. I
called Joe to get some help and was told that my radio, which has a
built in tuner would not accept more than a certain level of SWR and
was told to trim the twinlead back 19 feet. I did and while some of the
problem was solved, I continued to have problems on 75/80. I emailed
Joe to ask for further assistance and was told that the next step was
to buy a tuner extender (price $60). Not the answer I wanted to hear.
If in fact this kind of problem exists with radios that have built in
tuners, prospective buyers should know that in advance. For the cost of
the antenna and now the tuner extender, I could have bought a better
antenna, which is what I intend to do. I am not pleased with this
antenna and would not recommend it especially to someone who has a
radio with a built in tuner and intends to use it. Additionaly, the
performance on 40 seems to be very good. It seems to under perform on
20. Can't tell on 75/80 because I can't tune the band.

KC2GWK

Dave wrote:
No antenna will work across the full 75/80 meter band with low enough
VSWR to accommodate all radios. REASON: the bandwidth range +/- 13.3%
centered on 3750 KHz to the band edges is excessive. If you cut the
antenna for 3.9 MHz it most likely will not load up well below 3.7 MHz.
A tuner is required!! PERIOD.

For comparison, the bandwidth range on 20 meters centered on 14.175 is
only +/- 2.4%

Don't jump on condemning the antenna too soon. Do some more research and
ask more questions regarding 75/80 meters broadband antennas and what
"broadband" means.


Be kind folks! You're all correct, but don't bash the guy's head in.


75 and 80 meters is indeed quite a range to cover, especially when it
is actually 85 to 75 meters in wl.

I'd buy a tuner that will handle open wire feed, lose the 4:1 balun,
and get on the air.

- 73 de Mike KB3EIA -

On Thu, 08 Jun 2006 20:33:12 -0400, Mike Coslo
wrote:


I'd buy a tuner that will handle open wire feed, lose the 4:1 balun,
and get on the air.

Mike, did you notice "Mystery's" comment re spending more money on a
"tuner extender": "Not the answer I wanted to hear". She/he may be
even less interested in the spend on the tuner you describe.

I agree with you that antenna looks worth a try / perseverance, but it
will probably need a wider range tuner than commonly fitted internal
to transceivers unless you experiment (what's that!) to find a
feedline length that the rig/runer accommodates on all bands, or
switch feedline lengths.

Owen
--

Mike Coslo wrote:

SNIPPED

I'd buy a tuner that will handle open wire feed, lose the 4:1 balun,
and get on the air.

- 73 de Mike KB3EIA -

That's exactly what I use.

130 feet long center fed doublet with 600 ohm open wire tuned feeders.

Tuner is an OLD [30+ years] MURCH UT2000A with a balun.

Runs great on 75/80, 60, 40, 30, 20 meters.

I have used a LP for 20-10 meters. It is currently down as a result of QTH
change and limited $$$.

/s/ DD, W1MCE

Owen Duffy wrote:
On 8 Jun 2006 05:42:37 -0700, wrote:

Buyer Beware

same antenna I purchased. I bought the Cobra junior antenna and
followed the directions for installation. The antenna is 50ft in the
air in a flat top configuration. When I hooked it up to my radio, it
would not tune on segments of certain bands, most noticeably 75/80. I

That all seems pretty reasonable though the explanation that the
"built in tuner would not accept more than a certain level of SWR" is
not a good way to express the limits of internal tuners, but it is an
explanation that would appeal to those with lesser knowledge.

The problem is that antenna is advertised to work all bands.
Unfortunately it doesn't do very well on many bands.

The SWR is "off the scale" on many bands.

wrote:
The problem is that antenna is advertised to work all bands.
Unfortunately it doesn't do very well on many bands.

Sounds like a G5RV.
--
73, Cecil http://www.qsl.net/w5dxp

same antenna I purchased. I bought the Cobra junior antenna and
followed the directions for installation. The antenna is 50ft in the
air in a flat top configuration. When I hooked it up to my radio, it
would not tune on segments of certain bands, most noticeably 75/80. I

That all seems pretty reasonable though the explanation that the
"built in tuner would not accept more than a certain level of SWR" is
not a good way to express the limits of internal tuners, but it is an
explanation that would appeal to those with lesser knowledge.

The problem is that antenna is advertised to work all bands.
Unfortunately it doesn't do very well on many bands.

The SWR is "off the scale" on many bands.

The same would be true of almost any other doublet-style antenna, I
think. Such antennas are often usable on a large number of bands if
you have a wide-range transmatch/tuner, but I don't think I know of
any which are usable in this way with the limited-matching-range
"line flattener" ATUs built into modern solid-state transceivers.

The Cobra Ultralight is only about 60% as long as a normal resonant
near-half-wave dipole for 75/80 meters. It's shortened by linear
loading. I imagine it has a narrower SWR bandwidth than a simple
dipole.

The manufacturer states that a tuner _is_ required. The wording is
perhaps somewhat more optimistic about using a transceiver's built-in
ATU than is justified, though. I wouldn't plan to use an antenna of
this sort without a good external tuner with balanced-output
capability (whether intrinsic or via a good current balun).

The original poster might want to consider making a multi-wire (or
"fan") dipole. With several sets of wires it'd surely be possible
to make one which would tune on 80, 75, 40, and 20 well enough to not
need an external tuner... although fitting it into under 80 feet of
linear space might prove to be a challenge.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

wrote in message
oups.com...
Buyer Beware
I have read all the reviews and I am wondering if they are about the
same antenna I purchased. I bought the Cobra junior antenna and
followed the directions for installation. The antenna is 50ft in the
air in a flat top configuration. When I hooked it up to my radio, it
would not tune on segments of certain bands, most noticeably 75/80. I
called Joe to get some help and was told that my radio, which has a
built in tuner would not accept more than a certain level of SWR and
was told to trim the twinlead back 19 feet. I did and while some of the
problem was solved, I continued to have problems on 75/80. I emailed
Joe to ask for further assistance and was told that the next step was
to buy a tuner extender (price $60). Not the answer I wanted to hear.
If in fact this kind of problem exists with radios that have built in
tuners, prospective buyers should know that in advance. For the cost of
the antenna and now the tuner extender, I could have bought a better
antenna, which is what I intend to do. I am not pleased with this
antenna and would not recommend it especially to someone who has a
radio with a built in tuner and intends to use it. Additionaly, the
performance on 40 seems to be very good. It seems to under perform on
20. Can't tell on 75/80 because I can't tune the band.

KC2GWK

Lots could be wrong here including trying to kibbutz the problem from afar.
But it *sounds* like it is a combination of not enough tuner and a "bit" of
operator error. The internal tuners simply do not have enough capacity to
meet the demands of all-band operation in some cases. I have the Ultralite
Senior using the LDG Pro 100 tuner and I simply LOVE this antenna! I know
that there is loss on some bands, but any so-called "all-band" antenna is
going to be a compromise when compared to a dedicated, resonant antenna. I
don't even LIKE tuners, but I have some requirements beyond the Amateur
bands including US gov't SHARES and FEMA. I have to quickly move from one
band to the other and, in order to do so, I have to accept some loss.
However, I am VERY happy and surprised at the overall performance of *my*
antenna. Actually, I'm told that it is unusually loud for a 100 watt station
on a number of bands and quite readable on others (I don't HAVE to be the
loudest thing going to be effective).

I would guess----and that is what it is, a guess------that your internal
tuner doesn't have the ability to match this antenna-----AND probably a
number of others as well in multi-band service. Or you simply may have
overlooked something in the installation---like location or height above
ground.

For every 10 users of a product, there's going to be one, perhaps, that is
dissatisfied. With the Cobra, the reviews I have read are decidedly in favor
of both the Junior AND the Senior Ultralight. You can't win 'em all!


73

K4KWH