[TowerTalk] Re: Xfmr.

[n4kg@juno.com]

True.  (Series transmission line transformers are single band only.)

75 Ohm CATV hardline can be used on tribanders if made
a multiple of 1/2 WL on ALL three bands, ie, a multiple of
1/2 WL on 40M which is 1 WL on 20, 1.5 WL on 15, and
2 WL on 10.  

A multiple of 1/2 WL at 3.6 MHz can be used on 80, 40,
30, 20, 17, 15, 10M.  (30M is not an exact match, but close
enough for a pi-network to handle)

Impedances repeat themselves every 1/2 WL.

On 10M, if the lines are more than 300 ft then there is
a reversal between CW and SSB so long lines on 10M
probably need the series transformer solution or a
UNUN transformer solution (or switch  a 1/4 WL 
line in and out going from CW to SSB).

73,  Tom  N4KG

On Sat, 15 Apr 2000 15:38:50 -0400 (EDT) k8ej@ix.netcom.com writes:
> Obviously this is only useful on a monoband antenna - not a 
> tribander.
> Steve
> ----------------
> OOPS!   I goofed.  
> 
> A simple way to match 75 Ohm cable to 50 Ohms is to use
> a series transmission line transformer consisting of 0.08 WL
> of 50 ohm line followed by 0.08 WL of 75 Ohm line.
> 
> [ 50 Ohm Load ] -- [ .08 WL 75 Ohm ] -- [ .08 WL 50 Ohm ] -- [ 75 
> Ohm
> Cable ]
> 
> de  Tom  N4KG
> 

________________________________________________________________
YOU'RE PAYING TOO MUCH FOR THE INTERNET!
Juno now offers FREE Internet Access!
Try it today - there's no risk!  For your FREE software, visit:
http://dl.www.juno.com/get/tagj.

--
FAQ on WWW:               http://www.contesting.com/towertalkfaq.html
Submissions:              towertalk@contesting.com
Administrative requests:  towertalk-REQUEST@contesting.com
Problems:                 owner-towertalk@contesting.com
Search:                   http://www.contesting.com/km9p/search.htm