[TowerTalk] Beverage Questions

[n4kg@juno.com]

Long Delayed N4KG answers below:

On Sun, 26 Dec 1999 Chuck <dietz@texas.net> writes:
> 
> 1. I have a NE beverage which is about 14 ft high and fed with about 
> 250 ft of 75 ohm TV hard line.  I don't know how long the beverage is
> because it goes through dense woods/underbrush/sticker bushes.  I 
> was estimating 600-800 ft.  I have used the AEA Analyzer on the
beverage 
> and observed that when it is not terminated there are "dips" to low SWR

> at 1650 khz and 2330 khz with the lower freq. being a sharper dip to a
> lower SWR.  Does this mean I probably have an odd multiple of a 1/4
> wavelength at those freqs?
> 
> 5/4 W @ 1650 = 745 ft
> 7/4 W @ 2330 = 739 ft
> 
> Perhaps I have about 740 feet out?

	Sounds like a logical conclusion to me.
	Find the LOWEST frequency at which you get
	a dip and that is PROBABLY 1/4 WL, assuming
	your analyzer goes low enough.  I use an old
	HP-606 signal generator which tunes below the
	AM Broadcast Band and RF voltmeter to
	check transmission line lengths.  N4KG

> 
> 2.  When terminated with about 800 ohms, the SWR comes down to about 
> 1.8 to 1 in the 160 meter band.  Can I fine tune the resistance of the
> termination and get this lower?  Does it matter when it is already 
> below 2 to 1?  

	Best to terminate the Beverage in IT'S characteristic impedance
	(SWR will be constant across the spectrum if your matching
	transformer is uniform across the spectrum)  N4KG
	NO, any SWR below 3:1 will have minimal mismatch loss.
> 
> 3. Should I adjust the terminating resistance to minimum SWR and 
> then fool with the transformer if I want it lower?   See above.
> 
> 4. Should I put the AEA Analyzer at the antenna and adjust for 
> lowest swr then transform whatever the impedance is to 75 ohms?
>  
	Adjust the resistor for constant impedance vs frequency
	and then match to your feedline.  N4KG

> Has anyone tried to get the SWR down to 1 to 1?  Did it matter?
> 
	It doesn't matter much below 3:1   
	I use 9:1 matching transformers for all my Beverages.
	N4KG

> I have room for a 300 ft SE beverage.  Would one so short work?
> 
	It may be useful at times.  I have a 250 ftEast Bev and
	400 ft SE Bev which are especially useful on 80 / 40 
	and sometimes 160.  N4KG

> Thanks,
> 
> Chuck, KZ5MM
> 

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