Still not a problem Pete - but if he was asking how to reduce the SWR -
receive or not - that still didn't answer his question....just told him to
ignore it.
73,
Joe
WDØM
At 01:32 PM 11/18/2004, Pete Smith wrote:
Well, as a 'frinstance, if he's using RG-6 75-ohm cable, say 100 feet
long, and the antenna is presenting 240 ohms to the cable, on 1.8 MHz the
additional loss in the cable due to the mismatch is about .4 dB out of a
total of .8db, according to TLW.
73, Pete N4ZR
At 03:16 PM 11/18/2004, Joe - WDØM wrote:
Good point - how close is "close enough" - but if you're doing it the
first time, why not 'do it right" instead of having to do it over? :-)
73,
Joe
WDØM
At 01:11 PM 11/18/2004, Pete Smith wrote:
On the other hand, if it is a receiving antenna, do you care? The
additional loss in the feedline due to SWR *may* be trivial in this
application.
73, Pete N4ZR
At 02:51 PM 11/18/2004, Joe - WDØM wrote:
Hi Dave,
Perhaps the easiest way (if you have an antenna analyzer or access to
one) is to check the impedance at the antenna using an antenna
analyzer. That will tell you which way to go in modifying the turns
ratio. I just put a beverage antenna together, and the analyzer was
very helpful in assembling the transformer. I used my Autek analyzer -
and it's probably the best investment I've made to be sure every watt I
own gets to the antenna and then on to the other guy's radio. ;-)
73,
Joe
WDØM
At 11:47 AM 11/18/2004, Dave Quick wrote:
I recently put up a K6STI loop for 80m. It's about 8 feet off the ground
and built according to the plans in the Sep. 95 issue of QST. It's 21
feet on each side and I used 450 ladder (window) line and a 77 mix
ferrite bead for the transformer.
My problem is that I can't get the SWR below about 3:1 or so. I do get a
dip as I adjust the cap, but never below 3:1. I'm guessing that I need
to adjust the turns ratio of the transformer, which is 4 turns to 10
turns as the QST article specifies, but I'm not sure which way to go
with the turns ratio.
Does anyone have an advise for me?
Thanks.
Dave Quick K0EKL
_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with
any questions and ask for Sherman, W2FLA.
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_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions and ask for Sherman, W2FLA.
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