[TowerTalk] Stacking C-3 and EF-240S; EF-240S directivity
Mon, 16 Nov 1998 17:49:20 +0000
The biggest thing I have found with my stack of ef-340D's is that it is
IMPERATIVE that you really seal the linear loading tuning straps against water
penetration. The resulting corrosion (not even visible here) just kills the
pattern for me.
I think the lump loading is superior to the linear loading. I might change
mine over next summer.
Pete Smith wrote:
> Further to this topic, yesterday W9LT kindly came over and stood on the
> boom of my C-3 at 100 ft, while pushing the EF-240S up to about 6 feet
> above the tribander. SWR on the tribander on 15M changed almost not at
> all. So then he rotated the 40-meter antenna 90 degrees. That improved
> the 15-meter SWR some, and changed that on 40 somewhat. Reasoning that
> this configuration is the least likely to have harmful interaction, we
> decided to leave them at 90 degrees from each other.
> It's funny looking, but back in the shack, the directivity on 40m on DX
> seems definitely improved. F/S ratio is ca. 25 dB and F/B is 10-12 dB,
> about what I'd expect from 2 elements on a short boom. So last night I ran
> into EA5/M0AWR who has a 40-2CD at 75 feet, and we did some comparison
> tests. He confirmed the figures on my antenna, but I was amazed when he
> turned his Cushcraft. Front-side was closer to 35 db, and F/B seemed well
> over 20 dB. Granted, these are all TS-930 S-meter dB, but the better
> pattern on the 40-2CD was obvious.
> I know that antenna has a 24-foot boom, and the elements are also longer
> than on the EF-240S, but I was surprised at the difference. W9LT says that
> there has been some empirical work done that says lumped-constant loading
> like Cushcraft's is inherently superior to linear loading. I'd like to
> know more, and also wonder what the gurus of Towertalk-land think of this.
> PS -- I generated a huge pileup of weak Europeans on 40 last night, so I
> know the EF-240S is working well. Just wondering...
> Thanks all!
> 73, Pete Smith N4ZR
> "That's WEST Virginia. Thanks and 73"
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