| VK2CRB |
Rating:  |
2023-10-01 | |
| Comet Tell the full truth, please |
Time Owned: more than 12 months. |
Guys, you can either believe me or not. I cannot oblige.
There are 2 basic things, or I have been sold a faulty product or the antenna, which Comet says is a compromise and I was ultra fully aware of it, or it is a real dog until you put radials, yes or yes.
Background:
Bought this antenna 2 years ago as I did not want to make huge changes to my property or concrete roof tiles and their subsequent strengthening of metal poles to rafters.
Bought it from Gigaparts via eBay store from USA to Australia.
Antenna arrived in mint conditions and I utilized a metal tripode for satellite antennas with a mast and then guy ropes to set it up in the top of my concrete roof tiles.
Fed with a brand new CNT400 (luxury for HF but did not cost me money, a present).
Since day number one, noise and seldom could hear people.
SECOND PART:
Ultra fed up with this antenna I bought an MFJ 1836H but honestly, been in the box for year and a half. I never decided to put it up as not sure wind loading.
THIRD PART: a few weeks ago a friend that is an specialist in RF said:" Richard, buy a vector network analyzer, the one I have tested here with a professional Rhode & Schawarz Nano SAA2 N is very good and I am impressed with how close to this expensive German unit is.
I did that and started to do tests.
In 80 metres is A BIG DOG !!!!!!!! In parallel to that I decided to search in the net. UK and USA guys were experimenting with adding radials, the UK guy said it is a must.
So, yesterday afternoon I decided to add 4 radials and in 40 metres the 5-7 constant noise went to 0.
The Vector Network analyzer tells me that after the addition the SWR in 80 (that was and still a horror story at 3.5) has not changed. In 40, 7200 KHZ was 1.02 before the radials and now is 1.84 (makes sense, resonance moves and the software tells so). The rest is remaining at 1.2 or 1.3 up to 54 Mhz.
In summary the antenna with the radials starts to work with good SWR from 10 Mhz upwards.
MY CONCLUSION (unless I have a dud one):
Mr COMET this antenna NEEDS RADIALS.
I curse myself for having purchased this product.
It is more than a compronise, it is for the rubbish bin.
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| W6KMG |
Rating:  |
2022-12-24 | |
| It works |
Time Owned: more than 12 months. |
*Update* 12/2022
Took this antenna down due to not being able to participate in ham radio for a few years due to life circumstances.
I put it back up on a 30' mast with 16 radials as long as space would allow. Some are 60ft, some are 10, and everything in between.
It performs better than I remember it performing previously. Able to work 27 states and 5 countries in the couple weeks I've had it back up, and that's maybe 5 hours a week operating time tops.
Although I stand by my previous statement about it having slightly better ears than it has reach. I still give it a 4. It's not the worst I've used.
Original:
I acquired the CHA250b some months ago. I was looking for a vertical to mount on a 10' mast bolted to the side of my garage. The mast was already supporting another (wire) antenna, and looked like a great place to mount a vertical.
Not much room for radials, the way things are laid out, and I wanted a fairly light weight antenna. The CHA250b kept popping up in my searches. It seems like the ham community really has a love hate relationship with this antenna. I was a little hesitant that it can only handle 250w, but until i get an amp it shouldnt be an issue, and I dont work digital modes, so overheat shouldnt be a concern.
Assembled in a snap, hoisted the antenna up to the roof and mounted by myself. I placed a CMC 330 1k rfi choke right between the antenna and 50ft of lmr400 to the radio. Found low swr on every band with no tuner. Mast not grounded, no radials, no ground to antenna, only the coax. I have it guyed at only one point, and it recently survived 40+mph winds for a whole day plus.
I get good signal reports 80-10m. Mind you, my 80m contacts are mostly regional, and I only use 10m for local nets due to current band conditions.
On 40 and 20m, Ive made several DX contacts including Venezuela and Suriname, however the old addage "you can work them if you can hear them" does not apply here. A couple times since installing the antenna I could hear a far off station that could not hear me. Perhaps adding some radials would help, I currently have none.
I recently had a chance to attach a Rig Expert AA54 analyzer to my antennas thru their respective 50ft lmr400 feed lines. I found the CHA250b to be right around 2:1swr on 80m, 40 and 20m bands were under 1.2:1swr, and everything from 7 to 54mhz was under 1.5.
Swr sweep across the 80-6m bands was not anywhere near that good on my "no tune" wire antenna.
So ultimately, this is to me, a solid 4 star performer. Sure, its no woopty 5000 super dx death beam, but you already know that. It is a lightweight, low power handling vertical antenna for compromise installations that will enable you to make contacts with your ham radio transceiver.
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| VA3HAI |
Rating: |
2022-10-30 | |
| Works exactly as advertised! |
Time Owned: 0 to 3 months. |
I run an ICOM 7300 and had a lot of success with dipoles on the 10 and 20m bands. However, I wanted a multiband antenna to be able to transmit on more than one band at a time. The problem is I don't have room to run a bunch of radials, so after researching different options I chose the Comet CHA250B.
The antenna is very simple to assemble and the quality of the components is very good. Not knowing where I wanted to install it, I mounted a 10' aluminum conduit on a 3' tripod and attached the CHA250B approximately 12 feet off the ground. The antenna only weighs about 6 lbs so it is light enough for me to assemble and mount by myself. Once I had it mounted on the mast, I fired up my Icom to test it.
I was able to use the internal tuner on the Icom to transmit on all bands exactly as advertised, and made DX contacts on 10m, 15m and 40m with S9 signal reports. I did not have any issues making contacts on 80 or 20 meters and it is great to have an antenna that can utilize every band the 7300 is capable of transmitting on. Keep in mind I have this antenna installed fairly close to the ground, so it should have even better performance once it is permanently installed closer to the 32 feet that Comet recommends.
Overall, I am very satisfied with the purchase and am very satisfied with its performance so far. If you want a multiband antenna with a small footprint that does not require radials, I don't think you could go wrong with the CHA250B. |
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| K6DAV |
Rating: |
2022-03-09 | |
| Does Everything It Says It Does |
Time Owned: more than 12 months. |
I'll qualify everything I'm about to write by saying I'm a new ham and this is the only antenna I've used to date, so I can't give any comparisons to any antenna alternatives. I can tell you however, I'm totally satisfied with this product. Just as advertised, it's lightweight, extremely easy to set up, doesn't need a tuner and delivers me a SWR of under 1.3 to 1 every time I've measured it. I've had it almost a month now and have worked SSB contacts all over the western US (I'm in California) and FT8 contacts all over the country plus France, Australia, and Japan. It is pricey, but if you're looking for an alternative to having a dipole strung across your property, the CHA250B is definitely a viable choice.
UPDATE 3/8/2022 So the key phrase in my first review was "I'm a new ham... so I can't give any comparisons to any antenna alternatives." That has changed. I've used two antennas since this one, an EFHW and a
ZS6BKW, both of which are far superior to the CHA250B. Honestly, now I can't think of any reason to buy this, unless you just hate antenna tuners or radials for some reason. Save your money and get superior performance by avoiding this product. |
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| K6BRN |
Rating: |
2022-01-17 | |
| There are better choices |
Time Owned: more than 12 months. |
(UPDATED 1/17/2022)
This is a small footprint, quick to put up (but you must use a strong mast and mount - see below) antenna that is limited to low power input (50-100 Watts), is very inefficient on TX and mediocre on receive. However, it does a reasonable job on the power limited, channelized 60M band, where there are few to no "out of the box" 60M "resonant" antennas available (yes, you CAN "homebrew" one).
I've experimented with the CHA-250B at several different heights, from 5 ft above ground, attached to a steel tube driven 5 feet into the ground then raised to 10 and then 20 feet over moist, sandy soil, with and without wire radials. The antenna worked, but not very well in either RX or TX. Finally I put it up 35 feet on a roof mount, no radials, with a Palomar Engineers 5-bead choke on LMR400 coax, right at the feed point. This worked best.
In the roof position, the CHA-250B was usable (with low SWR) on ALL ham bands (including 60M) from 6-80M, though with the typical higher noise level of a vertical and relatively low transmit efficiency, especially on 80M. RX performance itself is mediocre (low RX signal strength), with quite a bit of noise, even with a CMC at the feed point and the coax shield grounded at the shack entrance. The CHA-250B works to a small degree on 160 meters, but the matching transformer heats up VERY quickly and can easily be destroyed. I was satisfied with it for a while, as a quick up, usable broadband antenna - which was very handy when my newer MFJ A3S suffered repeated trap failure (from mechanical drooping - another story altogether)
I later discovered that a smaller, simpler, cheaper end-fed half-wave wire antenna, with 49:1 matching transformer, like the EFHW-8010-2K, works MUCH better while handling much more power, and THAT's what I would have put up FIRST, before investing in the relatively expensive CHA-250B, had I known.
In all fairness, Comet makes no grand claims about the CHA250B, calling it a compromise antenna suitable for tight spaces or portable operation and covering 6M to 80M with good SWR on amateur bands. They recommend putting it up at lease 35 feet and adding a common mode choke to the feedline. I've found this advice to be correct. The antenna goes together in minutes, is very light but a little unwieldy during install due to its length. BE CAREFUL. Putting it up can be a 2-person job. It has a very long moment arm and is VERY flexible, multiplying the peak torque of any motion or windload on the mounting end, and any mast added to it lengthens the moment arm - So do NOT use a long, weak, flexible mast (like PVC tubing) or a weak mount. The lower tubing of the antenna iitself is double walled for strength, and needs to be for the same reason the mount/mast has to be strong, while the topmost tubes are fairly thin and very easy to bend when putting up - but once up, I've had no mechanical problems so far, other than a slight, permanent bend at the top in the prevailing wind direction.
Note that the CHA250B is NOT a resonant antenna. It is effectively a vertical random length antenna with a fairly complex (internally) multi-mode matching transformer at the base. Changing antenna length by a foot or two has minimal impact on SWR (I tried this). As such, on bands where it is electrically short (particularly 80M and 40M), the radiation resistance is low and the matching transformer absorbs a large percentage of transmitted power, which is why it is limited to just over 100 watts PEP input. On 6M, its pretty inefficient, too, on both RX and TX. The CHA-250B is NOT an antenna to use with an amplifier and the matching transformer can be destroyed even at 50-100 Watts (depending on band) by transmitting too long using a high duty cycle mode, like FT8. Mine failed within the first year and I had to replace the transformer (Comet supplied this under warranty) - now I'm MUCH more careful (yep - it's STILL up there).
In summary, there are better choices. Consider your options carefully before you purchase the CHA-250B. |
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| K3DMM |
Rating: |
2021-09-16 | |
| Works for me |
Time Owned: 3 to 6 months. |
| You may love this antenna or hate it but it does what I want it to do. Due to my HOA situation I was limited in my antenna options. I heavily researched this antenna before buying it. I run an Icom IC-7300 at 100 watts. Just within the last two days I've made DX contacts to the Czech Republic, Slovenia, Austria and Northern Ireland. They were on both the 20 and 40 Meter bands on SSB. I can make contacts all across the United States. All I can say again is that I'm very satisfied with this antenna. I may not always get through the pileup, but half the fun is trying. |
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| CT1JQC |
Rating: |
2021-06-21 | |
| Compromise antenna, but surprising! |
Time Owned: more than 12 months. |
I live in a building, so I have little chances of getting a big beam antenna, and no way possible to have an "antenna park".
But I also, wanted to use the most bands possible. Has I am in no way in a position to pay gazilions of money for an antenna, I had little choices.
So I went for this antenna, knowing that I wasn't going to be able to make it up a pile up, or even to make all contacts I could hear - you can't.
I know I was going to be limited in output power, in bandwith, and absolutely dependent on the gods of propagation to be able to make contacts.
And after almost a year of daily use, I have no regrets.
Yes, this is a compromise antenna.
You are not going to be able to break through pile ups.
You have to forget the "if you can hear them, you can reach them" motto.
But you are going to be able to make an FT8 contact to New Zealand, from Europe, of about 19447 Kms (12083 miles) with an -09 rst report - which I did just today, with a SFI of 74 and A index of 20 (really not good propagation conditions), that prompted this review.
Yes, beams are better, cobwebs, spiderbeams, titan's and pretty much all other antennas. But you get a good compromise antenna, for a couple hundred bucks.
It has allowed me to come back to amateur radio, and I love it.
From Lisbon (IM58is), I have worked all Continents, South Africa, New Zealand, Australia, Indonesia, Brasil, Argentina, West and Eastern USA, Canada, European and Asian Russia, Reunion Island, and I have psk reports of reaching Japan and DP0GVN (Antartica), with no more than 60/80 watts and this little antenna.
If you go for this, you have to be patient, but you will be able to make some good contacts, that will make you proud and enjoy the hobbie.
I've been able to work all the bands, but be aware, all serious DX was reached in the 15/17/20/30 meters bands - specially good in 20 meters (it is 7 meters tall, after all).
Digital modes? Good
CW? Good
SSB? Acceptable
I don't regret a single cent.
Although I want to add a 5 band cobweb to the same pole, I am keeping this baby, for its versatility.
Just remember, you have to be patient, and know you are not going to make all the contacts you can hear.
But the one's you make, you will celebrate them really hard!
73, stay safe, and good DX!
Edit: It's June 2021, and I keep stacking up contacts from all over the world. Calling this a "dummy load", is having really really high standards, or a gross misunderstanding of this antenna. 73's |
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| KD2UZU |
Rating: |
2021-04-09 | |
| Very good out of the box! |
Time Owned: 0 to 3 months. |
I did extensive research on this antenna before purchase including directly with the local distributor, Mick. Mick is very knowledgeable and honest. Telling me that this is a compromise antenna and if I had the space to put up a more traditional antenna. He suggested that I mount it about 35 feet AGL, which I did. Easy to assemble and install.
Minutes after checking the SWR's which were flat across all bands (except 10 meter 1:2:1) I got on the air. I live on the south shore of Long Island, my first contact was on 20 meters to a station in Northern Italy, my second contact was with a station in Austria both returned great signal reports. Today (day 2) I made contact with my 17 meter group, the net operator is in Texas, I have made contact with him many times in the past so he has a point of reference, he had a great copy on me, perhaps the best he has ever had.
I've read all the negatives, and if you compare this antenna to a yagi or other super beam or dipole it might not perform as well, but hey my neighbors and xyl aren't complaining and I've made some great contacts in just the first few hours. I run a Yaesu 991A at 100 watts, 100 feet of Rg8 coax and no ground radials of any kind.
3's
Tony |
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| K5GJQ |
Rating: |
2021-04-01 | |
| Poor performance |
Time Owned: 0 to 3 months. |
| I recently purchased the Comet CHA-250B from Gigaparts a short time ago and true to "advertised" and "reviewed" form it provided an excellent SWR across all bands with most providing an initial 1.0 to 1.5 before tuning. BUT!! it's deaf and mute on 17, 15, 12, 10 and 6 meters. No back ground noise or anything until 20 meters. Granted the instructions indicate 35', but due to our area (very small lot, restricted) 20' is as good as I can do. Still there should be better at the least reception. On our 10 meter net I can barely hear or be heard by a friend 5 miles away and nothing else. My radio is a Yaesu FT-950 at 100 watts. The MFJ 1798 vertical is going back into service. |
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| W2FKN |
Rating: |
2021-03-22 | |
| Amazing performance |
Time Owned: more than 12 months. |
| I have had this antenna for almost 5 years. HOA community so it is set-up in a clandestine fashion and painted to match the house siding. Run with a Yaesu FTDX5000 with flat SWR. Also run with an Expert Electronics MB1 SDR transceiver. Guyed at base and one section near top so no wind or weather worries. Does quite well and very satisfied. |
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