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Reviews For: Diamond CP6 multi-band trap-vertical

Category: Antennas: HF: Verticals; Wire; Loop

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Review Summary For : Diamond CP6 multi-band trap-vertical
Reviews: 44MSRP: 320
The CP6 is a multi-band trap-vertical antenna for HF bands, covering the 80*, 40, 20, 15, 10 & 6m amateur bands. Made from heavy-duty aluminum, the CP6 is easily assembled, yielding excellent performance and reliability from a compact base station.
*80m CW only. SSB requires a tuner.

This product has been discontinued.
Product is in production
More Info:
# last 180 days Avg. Rating last 180 days Total reviews Avg. overall rating
OE5RBO Rating: 2023-05-29
Okay when you know want you want/get Time Owned: 0 to 3 months.
I will do this as report of longer time, starting with the Antenna as new out of the box and first installation, first impression and adjustment.

Out of the box:
Got the small box containing the CP-6S with standard radial and did some preassembling in the shack.
- All items packed in a clean and arranged way.
- All drillings matching to their counterparts precisly.

Assembling is easy, the shipped instructions are compressed and to the point, but it´s enough to do the setup fast and successfully. So far - so good.
You´ll finish assembling in 1hour easily, after that the
adjustment can be done.
Adjusting the CP-6 is easy by modifing the length of the band-dedicated trapped radials. For every band, even for 80m, a good SWR was easy to achieve. 80m was best with 1:1,8 while all other bands came to 1:1,3.

Mind: I found the CP-6 to be very sensible to installations nearby like other vertical orientated installations.

While installing the antenna i did one modification i think that could be important as this should lower the "aging-factor".
The pipe that houses the adjustable element is pressed into the pipe that covers the trap, this pressfit is endangered for increasing resistance by oxidation and it is not accessable. So what to do? I put a welding over it, so both pipes are now fixed with an electric conductant bridge.
Did i said conductant? Yes! Also very important as the CP-6 is compact and need to meet its concept: Use copper-conductant grease on all concections!

And what do you get after all?
You get a working resonant antenna from 80m to 6m with limited but acceptable efficency, on the adjusted frequency´s you won´t need any tuner.
BUT: Mind that the resonant bandwidth is decreasing with increasing wavelength, from 20m downwards the usable bandwidth is slim like a needle, if you can accept this you will like the CP-6, otherwise this antenna makes no use for you. Full band coverage is not given!

Last remark:
Mind to buy the antenna with the proper 80m radial-kit to match your desired frequency-range! The manual is right here, as the standard-radial will come to 3,550 max.! The standard and the optional R1/R2 radial-kit´s precisly covers the indicated band-segment.

My summary: The antenna hits the bulls-eys in fulfilling its specification, no wonders happening - it currently (in condition "new") performs as expected on frequency´s that are to be set razorsharp, without any radials needed. I am satisfied at this time.

So let´s see whats time shows :-)
Update 29-05-2023:

Used a better SWR-measuring device to adjust the SWR, got 80m on used qrg now down to 1:1,38 and all other bands are about 1:1,15 in dry state / no wind environment.
IZ1PON Rating: 2021-03-23
Very good six bands vertical. Time Owned: more than 12 months.
I have had the Diamond CP-6 up for over 15 years and really like it. The antenna is very easy to assemble and tune; SWR always < 1,5 on all bands with my 100 watts on CW. The performance has been good. I have never had any problem with the construction of the antenna or the traps. A very good six bands vertical antenna made by Diamond.
G6YXV Rating: 2019-08-14
Good for the money Time Owned: 6 to 12 months.
OK so the "money" was zero, this came pre-owned with the pre-owend rig!
An old antenna that had had lots of repairs done and was showing it's age, cut my teeth on HF with this so steep learning curve with tuning, ongoing repairs, quite easy to dismantle as I had radials just above head height and could lower down and reach each section to dismantle. Never could get all 6 bands tuned at the same time, I'd get three in SWR then the other 3 would drop out...... But in all of that year or so of owning got some great experience and contacts over the pond and Russia etc. Good thing with a vertical is no tower or rotator to worry about, however with 200w limit I flogged it for £100 and switched to a beam to get more gain. I would seriously think of getting another, maybe the CP5 with higher power......
EI5KF Rating: 2018-03-06
Don't buy Time Owned: more than 12 months.
Unfortunately my experience has been bad. The traps are poorly constructed and fail in the wind. I've a useless heap of scrap.

Earlier 4-star review posted by EI5KF on 2012-01-16

CP6 cont'd......
After problems found with traps, contacted Diamond Japan, with issue of QC. New trap shipped with correct construction.
Thanks Diamaond
Earlier 2-star review posted by EI5KF on 2011-12-27

I purchased a CP6 in July of 2011. After getting my licence in August, I commissioned the antenna and worked satisfactory on 5 band (no tx on 6m)

After 2-3 months noticed a change in VSWR on most bands above 10m, then 10m when bad.

Eventually, I got the antenna down and checked the antenna out. Sure enough, O/C in the 1st trap. Dismantled antenna and trap. Found broken connection on bottom of 10m coil and bottom of 15m coil at earthing point. These breaks were basically down to bad design and construction of the trap. Only 2 rivits are used to secure the trap insulatated former to the aluminium sections. These rivits are only seperated by 45 deg, which results in a lot of play and movement of parts in the wind and snap! If Diamond had put 4 rivits at 90 deg spacing, no issue. Drilling thru and puting extra rivets solves the problem, re-assemble and away you go.

Now you have a damb good antenna which does not need a ground and is suited to restricted spaces.

With this modification done, I would give the antenna a 5, but as it is bad QC from Diamond it gets a 2.

Best Regards,
MI0GTA Rating: 2016-03-09
wait and see Time Owned: 0 to 3 months.
great, on the strength of the cp-5 I used some years ago when first licensed..

I've reordered a cp-6 today so it'll be a few mths before it's in the air..
Hopefully it'll do the job the cp-5 did back in 2002.
with th cp-5 I didn't have any issues, no faulty traps, no problems with swr.

at the moment I'm using a vertical delta loop from prowhip, and to be honest it failed within the first 12hrs it was in the air...

I replaced the wire, 24mts of it with a slightly heavier gauge wire and removed the plastic pole holders and replaced them with aluminium pole holders wrapped in insulating tape and a double u bolt on each holder, so it's been repaired and it work's fine now and resonant on 15m band...

i'll update this later re the cp-6..
VK2HFY Rating: 2015-08-23
Great concept, weakness in capacitive hats rusting at connectio Time Owned: more than 12 months.
Concept of antenna is great and trapped radial elements are useful when used in areas where real estate is limited.

After six months of use, I noticed that the capacitive hat radials towards the top of the antenna that were seemingly manufactured from a thin stainless steel tube with a threaded connection point at one end were rusting at the connection to the antenna.

I was stunned to discover that the threaded connection point to the alumninum ring holder was a MILD STEEL stub (with kurled edge and thread on one end) that was inserted into the end of each capacitive hat radial. I verified that the mild steel was attracted to magnets and therefore must have contained iron. Being dissimilar to metals around it, this promoted a galvanic effect and rust.... Difficult to detect when inspecting a new antenna as it appears that the entire assembly is stainless.

Surely all CP-6 antenna's if manufactured this way will rust and this is a potential (even likely?) point of failure in time both structurally and electrically.

Photos are here:
JO3SLK Rating: 2012-10-13
Great performance Time Owned: more than 12 months.
I have had the CP-6 for a couple of years and really like it. The antenna is very easy to assemble and tune. The performance has been outstanding, working all over the world. I am not a contester but I "hunt and pounce" on stations that I have not worked before. I have gotten through to some rare stations that were very busy, even with the 100 watt IC-7200 I have.

I have also been through several typhoons and the antenna has survived very well. I would recommend the CP-6 and would buy it again if I ever needed a replacement.

I use a RigExpert AA230 Pro to tune it to the portion of the band I will normally work and the antenna then just performs....

I have never had any problem with the construction of the antenna or the traps.

If you are looking for a good 6 band vertical that is easy to install, holds up well in adverse weather and performs well, this is an antenna to consider.
GM4LER Rating: 2012-10-02
Absolutly Rubbish Time Owned: more than 12 months.
This antenna is the worst piece of kit that I have ever bought.

It cannot stand up to any wx ,it's not water proof & traps built far to flimsy to remain operational after any wind ,

Probably ok for occasional portable use ,but do not rely that it will work as the connections in the traps are very fragile
G3EJS Rating: 2012-08-13
Very poor build quality Time Owned: more than 12 months.
I bought this six years ago to try and get active on HF from a very small garden, after being used to used to almost unlimited antenna space.

At first I thought it was great, seemed to work OK, but the only thing I had to compare it with was a piece of wire.

Went together OK, had to remove all but one of the top rods to get it to work on 80,

After about 18 months, I noticed the "sway" in the wind was jerky, very soon after that it stopped working.
As others have found, the construction of the traps is atrocious.

After repair it lasted a bit longer, but the plastic inside the trap is soft, and eventually it failed again, but the more holes you add for more repairs, the weaker it gets.

Last week I took it down and put up a Moonraker 2500. Although the Moonraker doesn't seem to get good reviews, it is a lot better than the CP6, signals well up, and hugely quieter regarding background noise (mainly local domestic)

The CP6 is sold in the UK as a quality antenna, at a high price. The quality is appalling, and it is worth about a third of the selling price. Now the price may be high due to large profits by the UK dealers, or maybe it is expensive from Diamond, but either way allowing for the quality and price it can only have a zero rating, comparing it with other makes like my TH3Jnr, which at 30 years old is still good.
KB9MLE Rating: 2012-03-25
Great antenna Time Owned: more than 12 months.
Have had the Diamond CP-6 up for over 10 years. Has worked very well. I'm starting to notice problems with my radio not being able to TX full power. Will have to look into this to find out what the problem is.