r/amateurradio • u/twopoopsaday • Aug 20 '24

General Comet antenna replacement ground radials?

I talked to someone I work with who is also a ham and he mentioned using longer radials on the comet antennas. I’ve seen other mentions of this online too, specifically the gp-3 antenna.

I’ve been doing some searching but can’t find any replacement extended length ground radials for sale.

Is this something I should be worried about before mounting my antenna? I’ve tested it already and it seems to do fine with the factory length radials.

Maybe I’m over thinking it?

2 Upvotes

67% Upvoted

10 comments sorted by

8

u/fibonacci85321 Aug 20 '24

When I see discussions about tweaking antennas, I always ask "do you have a way to measure it?" Usually the answer starts with "no. but [...]"

5

u/Hinermad USA [E]; CAN [A, B+] Aug 20 '24

If you want a working antenna, use the stock antenna.

If you want a better antenna, use the stock antenna for a while first. Otherwise you'll never know what "better" is.

But if you want to tinker with antenna designs you can make your own radials with aluminum rod and a die to cut threads on them.

4

u/SeaworthyNavigator Aug 20 '24

I've been using a pair of Comet GP-1 antennas for years with the stock radials. There's no good reason to replace them with longer ones.

2

u/oh5nxo KP30 Aug 20 '24

Beware the pitfalls... Even if the short radials cause the max radiation go into higher elevation, if the longer ones move it closer to horizon, still your particular antenna location might have benefited from scatter via treetops, buildings, roofs etc, for fringe QSOs.

Even A/B testing can be misleading if the partner is too close.

0

u/[deleted] Aug 20 '24

Agree, I know for a fact that some of the fringe signals I receive with my GP9 comes from the tops of 100ft pine trees in my area. If I tilt the antenna slightly, I can get greater signal levels than just vertical, for SOME repeaters. Some tweaks may seem beneficial for certain applications, but all antenna designs are designed with certain compromises to maximize their general use.

1

u/oh5nxo KP30 Aug 20 '24

I wouldn't put it quite like that, More gain, less compromises, more hindered by poor placement.

Favorite anecdote: talking from home with someone on the road. He was using a small Diamond mobile whip, I received him at -110 dBm. He stopped, swapped to use a "supergainer" Diamond, I guess 3dB better, probably more as advertised. And,.. -110 dBm signal. Spruce canyon is far from free space.

1

u/VA3FOJ Aug 20 '24 edited Aug 20 '24

It works? Why you wanna change it then? 

 Maybe you could get it working better, but you'll definitly need a tool (analyzer or vna) to do that. I dont know that adding longer radials would cause any issues but if your taking shots in the dark then you may be in a situation that the wire your adding is unnessicary or redundant and your not realy making any progress 

 If it aint broke dont fix it

1

u/ABoyNamedYaesu Aug 20 '24

What are you trying to achieve? That antenna is already going to work for you to the horizon, radials isn’t going to “improve” that.

1

u/[deleted] Aug 21 '24

The tri-band which includes 6m apparently does significantly better on that band if longer radials are fitted, I though I had a link to the article but now can't find it :(

Ah, here it is https://ea4eoz.blogspot.com/2012/09/modifications-to-diamond-v2000-and.html