Posted by
Rick WA6NHC-2 on
Oct 11, 2019; 4:20pm
URL: http://elecraft.85.s1.nabble.com/KX2-Antenna-Curiosity-tp7655612p7655660.html
Lyn,
That was at the old QTH in CA, here I'm using an inverted L for most
bands (temporarily) and a dipole for 80M (which came down in a
windstorm, couldn't take the weight of the 10' branch that hit it). The
match for 80M on the L is well beyond the range of the KAT500.
I'm shifting to a SteppIR DB36 (80-6M) and will single band the Inverted
L. The tower is up, I'm assembling the antenna now, in a race to beat
winter (already snowed twice in the last two weeks).
Next year, I'll make a new L in a better location and add a tuning
circuit to the L to allow it to resonate on 80/160M, giving me an option
for 80, rotatable dipole or vertical (and two RBOG) or diversity a few
different ways. Because of the lower noise here, the L plays well on
160M and I've enjoyed spending considerable time on the band.
My original point was to encourage simply putting up some wire; it will
radiate and it's a cheap and fun way to learn. Center fed makes it much
easier to tame (but that depends on what each leg is near too). Because
of local conditions (and lack of height), my dipole was 370', ~60' of
450 ohm window line, 4:1 common mode choke, 10' of coax. It had plenty
of pointy pattern spikes, not always in the needed direction and on 40M
it absolutely ROCKED. It was specifically NON-resonant on any ham band
yet provided some gain on most bands, once the tuner managed the load.
Even the existing (will be moved/rebuilt next spring) 160M Inverted L
was a 20 minute install that shouldn't work(but gave me over 100 Top
Band DX contacts last winter); simply a piece of wire over a tree (at
65'), a 1:1 CMC bonded to a water pipe for counterpoise (NOT efficient)
and coax to the shack. It's brought a lot of fun to ham radio (now that
I can hear without sub/urban noise).
73,
Rick wa6nhc
North Idaho
On 10/11/2019 8:52 AM, Lyn Norstad wrote:
> Rick -
>
> You may have a balun issue. I had problems too until I switched to the 1:1 / 4:1 hybrid (based on antenna analyzer measurements). And now, 160m matches fine for me. In fact, I made over 200 contacts (FT8, and mostly stateside) on 160m last week.
>
> The KAT500 is "supposedly" limited to matching up to a 10:1 SWR. That added 4:1 balun really brought the 160m impedance down to a manageable (and matchable) level.
>
> My ladder line feed is about 160 feet, then the balun, and finally about 13 feet of RG8XU to the KAT500.
>
> 73
> Lyn, WØLEN
>
> -----Original Message-----
> From:
[hidden email] [mailto:
[hidden email]] On Behalf Of Rick WA6NHC
> Sent: Thursday, October 10, 2019 6:17 PM
> To:
[hidden email]
> Subject: Re: [Elecraft] Center-fed antennas
>
> I have over 200 countries on a similar antenna, though I had to use
> another tuner than the KAT500, for 160M. Average height was about 35'.
>
> Just keep the coax short, like under 10' and as much center fed wire as
> you can put in the air, it'll play. It won't rock your world, it'll
> make you work for some of the DX, but that teaches patience and
> operating technique, still win-win.
>
> Rick nhc
>
>
> On 10/10/2019 1:56 PM, Lyn Norstad wrote:
>> I'm having great success with a horizontal center-fed "dipole" that has been sized (360 feet long) to be an Extended Double Zepp (4.7 dbi gain) and cut for the low end of 80 meters. I feed it with 600 ohm "True" Ladder Line from a Balun Designs Hybrid Balun (1:1 Current and 4:1 Voltage all in one case). A short run of coax from the balun to my KAT500, and I am in business at any frequency on 160 - 6 meters.
>>
>> It's oriented to be an effective NVIS radiator in a N-S pattern on 80m, by design, and to have major lobes on the other bands in other directions - also by design. For me, it's the most efficient and effective way to utilize our lot space (400 feet clear) and still be "under the radar" in our HOA.
>>
>> Birds seem to like it, and I find that it seems to be especially attractive to Hummingbirds, my XYL's favorites. A win-win, in my book.
>>
>> 73
>> Lyn, WØLEN
>>
>>
>> -----Original Message-----
>> From:
[hidden email] [mailto:
[hidden email]] On Behalf Of Al Lorona
>> Sent: Thursday, October 10, 2019 3:25 PM
>> To:
[hidden email]; David Gilbert
>> Subject: [Elecraft] Center-fed antennas
>>
>> My experience with single vertical or sloping wires is exactly the same as AB7E's. I have, over almost twice as many Field Days as Dave, come to a similar conclusion, with the slight difference being my preference for an "all-band dipole" fed with balanced line. This obviates the balun and reduces feedline loss to negligible, so obviously I am maximizing efficiency at the expense of any other possible advantage. (I can usually hear much better than I can be heard... so thus far this has been a valid decision.)
>>
>> To sum up what I and what I think Dave are saying, you can't beat a horizontal, center-fed wire up as high as you can get it. Its simplicity, the flexibility it gives you to QSY (with a good tuner), and its high efficiency are almost unbeatable.
>>
>> As a side note, the center-fed horizontal wire I have used here at home is totally non-resonant. I don't even know how long it is. Once you give up the obsession with resonant antenna length, you gain a huge freedom of choice.
>>
>> In the bottom of the sunspot cycle, these advantages are somewhat reduced because an op, especially on Field Day, might opt to forget about any band higher than 20 meters -- and these days even 20 is questionable. This means you can probably make do with coaxial cable and a balun for operation on 2 or 3 bands but the general idea still holds.
>>
>> Al W6LX
>>
>>
>>> Yes, a center fed normal dipole with the middle (high current portion)
>>> higher off the ground (say 50 feet for 40m) and a common mode choke at
>>> the feedpoint would almost assuredly perform better.
>>>
>>> 73,
>>> Dave AB7E
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