Posted by
Joe Subich, W4TV-4 on
Jul 27, 2009; 3:02am
URL: http://elecraft.85.s1.nabble.com/Diversity-Receiving-Antennas-tp3331122p3331709.html
> I've never used a K9AY but I know it's S/N is several dB
> inferior to a decent Beverage.
The K9AY directivity falls off pretty badly at 40 meters
and it becomes bidirectional broadside on 20. On 15 the
pattern is almost reversed and on 10 it's high angle.
This behavior is expected because the K9AY is more than a
full wave loop on 20 and 2+ waves on 10.
> you might want to consider a RX 4-square which can be
> comparable to a good Beverage in 4 directions and which
> can be used up to 30 MHz.
The receive four square antennas are lucky to maintain
performance over a 4:1 frequency range even with what
W8JI calls "crossfire feed." The diagonal (corner to
corner) distance needs to stay below approximately 5/8
wave to retain a unidirectional pattern but when
the size becomes too small in terms of wavelength, the
signal levels are too low to be useful in the lowest band.
The minimum effective size tends to be somewhat less than
1/8 wave per side on the lowest band (e.g., around 50'
for 160 meters).
73,
... Joe, W4TV
> -----Original Message-----
> From:
[hidden email]
> [mailto:
[hidden email]] On Behalf Of Bill W4ZV
> Sent: Sunday, July 26, 2009 10:24 PM
> To:
[hidden email]
> Subject: Re: [Elecraft] [OT] Diversity Receiving Antennas
>
>
>
>
>
> Dave Van Wallaghen wrote:
> >
> > So my question to the group is, for those using diversity reception
> > (or
> > separate receive antennas), and using a K9AY - does it
> perform well on
> > the HF bands for this purpose? I would also like any input
> from those
> > who have both Beverages and K9AY for comparison. And, does
> it make sense
> > to use the setup as I described? Since I can only run
> Beverages in a
> > couple of directions, I thought the K9AY use in the other
> directions
> > would cover a lot of bases.
> >
>
> I've never used a K9AY but I know it's S/N is several dB
> inferior to a decent Beverage. There's a good comparison of
> RX antennas below:
>
>
http://www.w8ji.com/receiving.htm (scroll down to comparison chart)
>
> Another comparison in in ON4UN's Low Band DX-ing (4th
> edition) on page 7-97.
>
> The short answer is...the K9AY is better than nothing,
> occupies little space and can be switched in 4
> directions...but it's not in the same ballpark as a good
> Beverage. I'm also not sure how well the K9AY works on the
> higher bands, but you might want to consider a RX 4-square
> which can be comparable to a good Beverage in 4 directions
> and which can be used up to 30 MHz. DX Engineering and HiZ
> Antennas both make broadbanded RX 4-squares that work well at HF:
>
>
http://www.dxengineering.com/Sections.asp?ID=117&DeptID=12#Top>
http://www.hizantennas.com/>
> These systems are not cheap but should work much better than a K9AY.
>
> BTW, it's really doubtful your Beverage is actually working
> correctly. Both ends should be terminated in the
> characteristic impedance (~500 ohms) to work correctly, so
> you need a non-inductive 470 ohm resistor on the far end and
> a 9:1 matching transformer on the feed end. Transformers can
> be made to work well up to at least 20m (maybe even 15m) but
> require some care in construction.
>
> This is not the place to go into a Beverage tutorial but
> there is a wealth of information on W8JI's website and in
> ON4UN's 4th edition (or you can wait for his 5th edition
> which should be out next year).
>
> 73, Bill W4ZV
>
>
>
> --
> View this message in context:
>
http://n2.nabble.com/Diversity-Receiving-Antennas-tp3331122p3331589.html
Sent from the [OT] mailing list archive at Nabble.com.
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