[Elecraft] [BL1] Seems lossy in all useful configurations

[Vic K2VCO]

David Woolley wrote:
> I tried using a BL1 (4:1) with my K2 and KAT2 to allow earth free 
> operation using an improvised antenna in a first floor (US = second 
> floor) flat, but I've come to the conclusion that under almost all 
> circumstances, even though I'm getting reasonable SWRs, most of the 
> power is going into heating balun.
> 
> I'm sure that this is partly through not originally understanding the 
> limitations of baluns, in particular that they are only really usable on 
> the equipment side of a balanced antenna coupler that presents the 
> design impedance to the balun, or an antenna that does this without a 
> coupler, so don't really make sense when impedance matching is done on 
> the equipment side of the balun, as in the KAT2.

There is no difference if the balun is on the input or output side of an 
unbalanced tuner. See

<http://fermi.la.asu.edu/w9cf/articles/balun/balun.html#SECTION00050000000000000000> 


I assume that you are using the balun because the antenna is balanced. 
If not, just use the KAT2 directly.

I just recently set up a similar system, a balanced antenna with a radio 
that has an unbalanced tuner built in. What I did was measure the r and 
x presented by the feedline with an antenna analyzer. It turned out that 
on the two bands that I was concerned about, r values were between 15 
and 150 ohms. But there was significant reactance (in my case, inductive).

When I tried loading the antenna directly through a 1:1 balun there was 
significant heating. And the SWR was very high, making it hard for the 
internal tuner to find a match. I then added some capacitors in series 
with the feeders to cancel the reactance.  I used a compromise value 
which did not reduce it to zero on both bands, but made a significant 
dent in it.

As a result, it was possible to load the antenna on both bands with no 
detectable heating of the balun.

I suggest that you start by determining what you are dealing with by 
measuring the r and x. You may be lucky and have a situation that can be 
handled without any switching, as I did. Or you may have a super-low 
resistance on some bands, large reactances of opposite signs on 
different bands, etc. In that case you might be able to improve the 
situation by changing the feedline length.

I would not try to fix this by changing the balun. Knowledge is power: 
find out what you are trying to match!
-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco