George:
First from my point of view, 4:1 baluns should not be used in this
application. I wouldn't expect it to work. Based on your antenna/feedline
configuration the actual feed Z of the antenna may be more near 25 ohms.
Thus with a 4:1 balun the load the tuner must match is 25/4 or 6.5 ohms.
Very few if any tuners will match efficiently below about 15 ohms.
You should be using a 1:1 current balun in all applications, all
configurations. The 4:1 balun should reside in the trash can.
History: 4:1 baluns became popular due to hams making folded dipoles from
TV type line or open wire line. In this configuration the resonant feed Z
is more like 200 to 300 ohms. Thus with a 4:1 balun the load to the
transmitter is in the order or 50 to 75 ohms which is great for most
transmitters with those being link coupled outputs or with the new pi
networks.
Happy New Year
73
Bob, K4TAX
----- Original Message -----
From: "George K" <w2yj@highstream.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Friday, December 30, 2005 2:12 PM
Subject: [TenTec] ORIONII_INTERNAL_AT_TUNER
> My original Orion with internal tuner would not tune the lower ends of 80
> and 160 meters.
> The antenna is a 270 foot center fed with open wire terminating at a 4:1
> balun outside the shack and then on into the OrionII rig with 20 feet of
> coax.
> The OrionII has no problem with either band on the lower ends tuning to
> 1.2:1???
> Did TT beef up the tuners capabilities in the, new and improved,
> OrionII???
> If not I can't think of what I may have done since receiving the OII.
> I'm elated, but in a quandary.
> George
> _______________________________________________
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> TenTec@contesting.com
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>
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