[GCARC] Comet CHA-250HD antenna comments

Wed Nov 15 17:37:35 EST 2023

I am not going to get into a this antenna is better than that antenna, since everyone on this thread is more knowledge than me. Antenna theory is not my strong suit.

Saying that, I got 7BDXCC mostly with dipoles at 35 feet, and some verticals, including way back when I started out with a 5BTV. I did most of my 40 and 80M DXCC work with a trap dipole, and an OCF, at 35 feet. It took work, but I was able to get it done. In addition, the verticals on low band, especially on 80M, have very limited bandwidth. The 5BTV, only covers 80 KHz of the 400KHz allowed on 80M band.

At first, we have to see what exactly he wants to do. Does he want to ragchew all over the world, or chase DX? What bands does he want to work? What does he have to work with, land-wise. What height does he have available. Etc,

The reason I suggested an OFC, is cost and performance. I have done very well with it, and a balun and wire is likely to cost him under $200. A vertical is not cheap, and then you add the mounting and radials, and you can easily cost him $500.

So, I guess we need to find out what exactly he intends to do and what he has to work with.

Vinnie N4NYY

________________________________
From: Kenneth Bozarth <kwbozarth at gmail.com>
Sent: Wednesday, November 15, 2023 4:04 PM
To: Vinnie Sallustio <yankees_1996 at hotmail.com>
Cc: Tony Starr <tstarr1450 at gmail.com>; Jeff One <djgrath1 at gmail.com>; gcarc at mailman.qth.net <gcarc at mailman.qth.net>
Subject: Re: [GCARC] Comet CHA-250HD antenna comments

My two more cents - keeping with verticals, since they are the best antenna for DX on low bands unless you get a wire very high...I have extremely good performance with my R8. 40m is not very wide so you gotta pick your portion of the band, and a tuner takes care of the other end if you don't run legal limit. No radials, but it has a set of short steel wire radials for capacitive loading. Mounted on a 10' mast, it really works and is self supporting. The matching transformer will handle legal limit inside the low SWR band. If you need 80m, the R9 is good, but may need a set of guys, and again, bandwidth limited. As for ground mounted verticals with radials, you do not need 1/4-wave radials. Twice as many short ones work better. I have a ground mounted 33' vertical for40m and onlyabout 16 radials and I get out very good with it. The 43-foot vertical has proven to be a great antenna but you need a base tuner, such as the MFJ998RT for high power (pricey). On 40m, if you can get a wire at 50-60', you'll do very well. And, if you don't care about long haul DX on 80m, that wire will work OK on 80m. I use a fan inverted V on 80m and 40m with apex at about 55' and it works.

On Wed, Nov 15, 2023 at 3:12 PM Vinnie Sallustio <yankees_1996 at hotmail.com<mailto:yankees_1996 at hotmail.com>> wrote:
He's going to need a pile of ground radials with the 5BTV ground mounted, which is totally doable. If the 5BTV is installed, he will need tuned radials, which for 40 and 80 would be very long.

Does he have any trees? If so, how much space does he have? I use a OCF with 4:1 at 35 feet, and get all over the world with it. 6:1 if he is up 50 feet.

Get Outlook for Android<https://aka.ms/AAb9ysg>
________________________________
From: gcarc-bounces at mailman.qth.net<mailto:gcarc-bounces at mailman.qth.net> <gcarc-bounces at mailman.qth.net<mailto:gcarc-bounces at mailman.qth.net>> on behalf of Tony Starr <tstarr1450 at gmail.com<mailto:tstarr1450 at gmail.com>>
Sent: Wednesday, November 15, 2023 11:22:21 AM
To: Jeff One <djgrath1 at gmail.com<mailto:djgrath1 at gmail.com>>
Cc: gcarc at mailman.qth.net<mailto:gcarc at mailman.qth.net> <gcarc at mailman.qth.net<mailto:gcarc at mailman.qth.net>>
Subject: Re: [GCARC] Comet CHA-250HD antenna comments

Jeff,

All that Charlie,  or anyone else considering this antenna, needs to know
about it, is contained in this very honest paragraph on the DX Engineering
website"

*This improved Comet CHA-250HD features a new solid whip replacing the top
aluminum section for greater flexibility and less strain on the lower
sections in high winds. The “magic” behind the CHA-250HD is the transformer
matching section. The transformer on the original CHA-250B had smooth
sides. This improved design features a heat sink to dissipate the heat
created inside the transformer from the RF that enters the power feeding
section rather than transmitted as RF. This is the compromise needed to
create a broad-band, low SWR, multi-band HF antenna withinimal visual
impact.*

Basically, it comes down to this:  Antenna "matching transformers" should
not feature heatsinks or cooling fins.  If they do, it is a dead giveaway
that they are HIGHLY in-efficient.  Unless you have lots of power ( and
money ) to waste, there are many other vertical antenna choices that you
can make which will put more RF in the air, and keep more money in your
pocket. My favorite choice, which I own, would be the Hustler 5BTV, but
there are many others, all of which will perform better than the Comet
CHA-250 series.

Tony K3TS

On Wed, Nov 15, 2023 at 8:56 AM Jeff One <djgrath1 at gmail.com<mailto:djgrath1 at gmail.com>> wrote:

> All,
>
> Charlie Wahl, KC2STO is asking for some comments on purchasing a Comet
> CHA-250HD HF antenna. Please respond directly to him at 856-656-6122.
>
>
>
> Thanks
>
>
>
> D. Jeffrey Garth
>
> 621 Greenbriar Drive
>
> Williamstown, NJ 08094-1149
>
> 73, WB2ZBN
>
> Club Publications
>
> www.w2mmd.org<http://www.w2mmd.org><http://www.w2mmd.org>
>
>
>
> "Choose a job you love, and you will never have to work a day in your life"
> - Confucius
>
>
>
> ______________________________________________________________
> GCARC mailing list
> Home: http://mailman.qth.net/mailman/listinfo/gcarc
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:GCARC at mailman.qth.net<mailto:GCARC at mailman.qth.net>
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
______________________________________________________________
GCARC mailing list
Home: http://mailman.qth.net/mailman/listinfo/gcarc
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:GCARC at mailman.qth.net<mailto:GCARC at mailman.qth.net>

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
______________________________________________________________
GCARC mailing list
Home: http://mailman.qth.net/mailman/listinfo/gcarc
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:GCARC at mailman.qth.net<mailto:GCARC at mailman.qth.net>

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html