I put out a 160 foot run of 7 eights heliax last year. Worked great. Last
time I was
QRV was end of January, 2017.
I recently put some RF out (100 watts...HP for me) and was surprised to see an
SWR in the
shack of about 3:1.
Setup:
Outdoor antenna switch box just outside the shack.
>From there, very short run of RG8 (under 4 feet) to "start" of Heliax.
160 foot run of Heliax to "back" tower.
Then another "short run" of RG8 to about 80 feet of RG217, which goes "up" my
crankup tower.
What I have done:
Put a dummy load at the rig: shows 1:1 SWR.
Put the dummy load at the "far end" of the heliax by "breaking" the connection
from the
Heliax to the short run of RG8. SWR in the shack still 3:1 (all HF bands).
Put the dummy load at the end of the short run of RG8 coming from the antenna
switch box.
SWR in the shack shows 1:1 (dummy working, coax to that point working).
OK, so seems like something is wrong with the Heliax.
I disconnected the Heliax at both ends. If I short inner to outer, it shows
dead short at
the "other" end. I know, DC is not RF.
I measure the resistance between center conductor and outer shield of the
Heliax. I expected
"infinite," but using my crappy RS ohmeter, it shows about 500k ohms. I
measured other runs
I have RG217 (nothing connected at either end, about same length), and the
crappy RS meter
shows infinite, as expected.
So what could go "wrong" with my 7 eights inch Heliax? It is above (on) ground
for the entire length.
I walked it yesterday, picking it up about every 10 feet. Looked "normal" to
me.
Any help/suggestions?
Thanks,
de Doug KR2Q
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