Hi Bill, I recently built a KAT100 and 4:1 BL1 also (3 evenings too!). I
have a 160/80/60m trap dipole in ANT1 and a 40m doublet via the balun in ANT
2 for the other bands. This gives me instant QSY on ten bands. Like you,
by coincidence, I find the balun gets very hot on 40m. What I plan to do is
experiment by putting some L (tapped coil) across the balun on the balanced
side to cancel out some of the reactance on 7MHz. (I've tried adding C but
that was going the wrong way as it didn't help). I think doing this should
reduce the 7MHz balun losses, and I suspect won't effect the higher bands
too much.
73 Fraser G4BJM #4368
From: "Bill Strong" <[EMAIL PROTECTED]>
To: <[email protected]>
Subject: Re: [Elecraft] Tuner losses
Date: Fri, 20 May 2005 23:09:13 -0000
Andy,
I want to give you a follow-up. I built the KAT100 in less than three
evenings and it is a wonder to me in both its design and operation.
I built the BL1 in the 4:1 configuration. I get a 1.1:1 or less match on
all bands except 15 Meters which is about 1.5:1. I find that the balun
gets hot enough to fry eggs on 40 meters (even at 50 watts with SWR of
1.0:1), mildly hot on 30 meters, cool as a cucumber on 20 meters (even
at 100 watts), and slightly warm on 17 meters. I guess that on 40 meters
the balun is at a current node. The feedline is about 100 ft long on the
140 ft Cobra Ultralite 80 doublet antenna. I don't know that I want to
get into trimming the feedline as I may affect 20 meters. I am able to
make contacts on 40 meters although I would assume I am operating at
reduced efficiency. The BL1 when very hot does not desaturate and make
the SWR rise above 1.0:1.
I want to stay with 300 or 450 ohm ladder line so I may put another
antenna up for 40 meters. I manually disconnect the antennas outside the
house when they are not in use. Our area has a lot of thunderstorms.
I guess I can buy a heavier duty balun from DX Engineers; however, I
notice that DX Engineers has a new multiband antenna for sale which is
fed with ladderline along with one of their big baluns. I am going to
look into it.
I ordered another BL1 which I am going to build in the 1:1
configuration. I want to see what if any difference this might make
before I decide whether or not to get a bigger balun and/or another
antenna.
Thanks for your help,
Bill
WA5KPE
Hattiesburg, MS
K2 #4454
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