Diamond CR11 Mobile Antenna Review

Background

In Australia, the 27MHz CB Retail market has completely dried up.  The major brands, GME & Uniden, no longer even offer a SSB Model to Australian Customers (GME possibly doesn’t have one full stop).  This is despite the fact that 27MHz CB, SSB especially, is as popular as ever in Australia.

While the reasons for this are best left to a dedicated article, in a nutshell 27MHz SSB offers something that no UHF CB system can: The possibility of Worldwide DX (Americans are easily heard almost every single day), and a relative freedom from idiots (who have now taken over UHF CB).

Wanting every communication method allowed available to me, I decided to fit a 27MHz CB to my 4WD.  As I am sure a lot of people will tell you, when you’re stuck in the outback, its handy to have a range of different communication offerings.

Unfortunately, due to the aforementioned lack of products in the market, my mobile antenna choices were basically limited to generic 3 foot centre loaded fibreglass whips.  Not to say they don’t work (they do, and not too bad), it is a little disappointing when you go to all the auto stores and electronics stores and find almost identical products in slightly different packaging.  So when I was at a local ham store and saw the Diamond CR11 Mobile 26-28MHz Base Loaded Whip, I decided to give it a go!

Overview of the Diamond CR11

cr11_e

Technical Specifications

  • Model: Diamond CR11
  • Length: 1.65m
  • Weight: 360g
  • Power: 200W AM
  • Impedence: 50 Ohm
  • VSWR: Less than 1.5:1
  • Connector: UHF / ‘M’ Type
  • Type: 1/4 Wave (Base Loaded)

Target Market Segment

While Diamond market this antenna as an Amateur product, and indeed, Amateur retailers are the only places you will find it, I couldn’t help to notice that the 27MHz CB Band appeared to be right smack bang in the middle of its claimed bandwidth.  As such, I reasoned that it would be a decent performer on the Australian 27MHz HF CB Band Allocation – I was right!

Performance

Assembly & Installation

Straight out of the box – the top & bottom elements were connected together with the help of the included Allen Key.  The antenna was screwed into my existing nudge bar mounted SO-239 Jack.

Although the manual offers tuning advice, none was undertaken & none was needed.

SWR Performance

While undoubtedly your millage may vary (this is HF), straight out of the box the antenna produced a SWR of 1.3:1 when mounted on my nudge bar, and 1.0:1 when mounted in the centre of my roof on a mag mount – this confirmed my hypothesis that it would make a suitable 27MHz CB Antenna.

Receive Performance

Having owned this antenna for some time now, I can say I am very happy with its receive performance.  Quite often I am able to hear many US stations (who are not necessarily staying within FCC Limits, read: probably running 1kw+), and even other exotic places such as New Zealand (Kiwi Bob anyone?  He is a quite well known member of the ‘World Radio’ CB Club, and frequently targets Australia with a Yagi Beam Antenna from his Home Station).

If I bother to climb the local hill, I can hear (and frequently work) a bunch of stations across Victoria & even as far as a mobile in Western Australia.

Transmit Performance

When connected to a type approved Australian 27MHz CB, obtained from decades past care of a good friend, operating at the full 12 Watts PEP SSB, I am typically able to communicate 10-15Km ‘As the bird flies’ from ground height (not up a hill).

If I take the opportunity to climb a local hill, I have been able to work such far flung places as another mobile in WA, and even New Zealand (from Mt Dandenong, on a good day, weakly).  Rather impressive for an old radio using ‘old technology’!

Conclusion

My experience with the Diamond CR11 Mobile Antenna has lead me to conclude that it is indeed a great antenna for use with 27MHz HF CB.  While I haven’t been able to compare it with many ‘classic’ CB Antennas of days past, it easily outperformed an old ‘Thunderstick’ I obtained with the Uniden GrantXL CB Radio used in the test.  That is not to say the Thunderstick is inferior – unfortunately my ‘sample’ was 20+ years old, had been previously ‘trimmed’ for tuning in another setup, and the adhesive on the whip was worse for wear.

Pros

  • Bullet Proof Construction: Stainless Steel, with bending joint for fold over / protection
  • High Power Handling: 200w AM means you can use it for 10M as well!
  • Brand New: there are not many brand new offerings these days
  • Great out of box performance
  • Two piece construction allows for storage

Cons

  • Not as cheap as a 3 Foot generic from Jaycar or Autobahn
  • CB Diehards won’t know what the heck it is when they ask and you say ‘Diamond CR11’

Overall, I am very happy with the antenna, and would not hesitate to recommend it to any 4WD guys who wanted a 27MHz setup in their truck.  I also like the fact that I can use it when combined with a coax switch as a resonant 10 Metre Antenna.

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