I'd presume the actual VSWR is higher than you're reading, since it's being
improved by the loss of 350 feet of 52 Ohm coax..... -WB2WIK/6
"If everything seems under control, you're just not going fast enough." -
Mario Andretti
> -----Original Message-----
> From: Kent Miller [SMTP:K4MK@triad.rr.com]
> Sent: Wednesday, October 02, 2002 7:41 AM
> To: Mark Pride
> Cc: towertalk@contesting.com
> Subject: Re: [Towertalk] 40 m yagi matching
>
> Hi Mark,
>
> How high is your swr on the upper end ? My 40-2cd is tuned for 7.150,
> but at the worst case at 7.000 the swr is only 2.2 to 1.0 and at 7.300
> it is only 1.7 to 1.0.......
> My antenna is at 130 ft. and is fed with 350 ft. of 52 ohm coax. I'm
> using a coax balun wound on a 6 inch core mounted at the driven element.
>
> I find an swr of 2.2 to 1.0 acceptable, but many hams would not, I
> suppose.
>
> 73,
> Kent - K4MK
>
> Mark Pride wrote:
>
> > Fellow TTer's: Problem - Have a 2 element yagi on 40 M that is
> currently tuned for the CW end of the band. In order to use it on the SSB
> end, past techniques have included locating a Transmatch at the base of
> the tower and adjusting the match so the amplifier can tune properly -
> this has proved difficult as it was inconvenient to re-tune for other
> portions of the phone band (tower base is 300 ft. from the shack and the
> bandwidth with the tuner was not too great); another approach used was to
> locate the tuner in the shack - made it convenient to re-adjust as
> necessary, but caused severe voltage breakdown conditions on the feed line
> (high SWR plus the amplifier proved disasterous for connectors).
>
> What are others doing to make the SWR better on the opposite end of the
> band the antenna was originally tuned? Have considered adding stubs
> somewhere on the feedline, but have not tried as yet. Looking for a
> way to allow the amplifier to tune properly across the entire phone
> band even though the antenna's performance is degraded due to a
> non-optimzed setting of the elements for that part of the band. 40 M
> phone is not my favorite but with this problem fixed, I can at least
> make a better score in those DX contests. (That's the plan anyway!)
>
> I realize this is transmission line theory 101, but thought there
> might be a quick answer out there!
>
> The yagi is a Cushcraft 402 at 100 ft. fed with 3/4 - inch diameter 75
> ohm hardline (300 ft. plus 100 ft. up tower).
>
> Regards,
>
> Mark, K1RX
>
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>
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