Dipole question

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NightProwler
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Dipole question

Postby NightProwler » 09 Apr 2017, 18:31

Right im using a Yaesu FRG7700 with matching ATU and it's connected to a 4.1 balun with about 28 feet of wire running each way and mounted about 20 feet off the ground. This works really really well until you get up to about 15MHZ then it starts going deaf. I was told it's because the two lengths of wire are the same length, So should I shorten one? Would this 'wake' up the top end of HF a bit?

Cheers all...Rich :thumbup:
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ch25
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Re: Dipole question

Postby ch25 » 09 Apr 2017, 18:43

Google for fan dipole, t2fd, tc2m antennas.

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Admiral
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Re: Dipole question

Postby Admiral » 09 Apr 2017, 19:31

Most HF sets go quiet after 20Mhz compared with below 20Mhz, that's the nature of the beast, technically HF becomes VHF at 30Mhz, in reality when there is no sun spot activity, VHF kind of starts at 20Mhz, you can Google all you want for antennas and gizmos, but for the next 8 years or so post 20Mhz will be as flat as a pancake on most days.
That's also why in a few months the World and his wife will be trying to shift their 11m kit on eBay and elsewhere, so if you're looking for an 11m bargain just hold out for a few months and they will be virtually giving it away, I can see 5555 and clones at around fifty quid soon.
PS if you haven't already, then 7700 and 8800 seriously need a recap right now due to age. The 8800 I recently sold got a recap from a club member for beer money as my eyes and arthritis aren't up to the job these days, the kit cost me £13 and he charged me a tenner for his time, moral being join your local club because there are some great people out there.
I sold my FRG8800 for £110, which may seem a lot for a 30+ year old receiver, but it had the £23 recap and the FRV8800 VHF converter in it which can exchange hands for £50 on its own as they're like hens teeth these days, so someone got a crisp radio at the top of its game, with VHF for the price of a night out, and the 7700 and 8800 were engineered properly in Japan, none of the modern Chinese cost cutting crap,
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paulears
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Re: Dipole question

Postby paulears » 09 Apr 2017, 22:26

I'd leave the dipole as a dipole. Asymmetric dipoles tend to be much more 'spikey' in their performance. You might get the appearance of better performance on one band but find the others less good, or having nulls in the polar pattern that were t there before. As soon as I go above 14MHz I notice each band is quieter noise wise, but when the conditions are right they suddenly perk up. Why not try to add a little to one? Easier than cutting a good one down. I bet it's the same or probably worse overall.

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NightProwler
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Re: Dipole question

Postby NightProwler » 10 Apr 2017, 10:35

Cheers all. I never thought about re-capping my Yaesu so I guess thats a another job one day. Since the weather is nice I might go down the fan dipole route, Not sure why I didnt think of that before. I got 28 feet of wire running each way so I might add two more wires at 14 foot each and see what thats like. It's all about experimenting I suppose :thumbup:
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NightProwler
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Re: Dipole question

Postby NightProwler » 05 May 2017, 13:59

Well I finally sorted the dipole out, I added another 2 lengths of wire at 14 feet each way. So thats 28 foot of wire each way and a foot below I got 14 foot of wire each way and it's made a hell of a difference :thumbup:
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