[Elecraft] Stealthy Antenna and W1CG Balun

[Ron D'Eau Claire]

Sounds like a nice setup, Brent! 

One thing to keep in mind when using common banana jacks mounted in a
metal panel is that they can fail if you happen to have a high enough
impedance at the rig end of the feeder, even at 10 watts.

Some years ago I had a home brew 15 watt rig and was feeding open wire
line through a balun. The feeders were attached using banana plugs
mounted in a panel like you described. One day I smelled something funny
as I was tuning up on a new band for the first time. Then the SWR went
crazy. Investigating, I found that one of the banana jacks had melted so
the conductor shorted to the metal panel. 

I had happened to hit a combination of antenna and feeder length where I
was very close to a voltage "loop" (high impedance point) at the
transmitter end on that band, and the r-f voltage was enough to melt the
jack, even at only 15 watts or so of r-f. 

Even if it hadn't melted, precious r-f watts were being used to heat
that insulation instead of being radiated. A common observation by many
ops is that if a part doesn't get hot, it's not lossy. The problem is
that at low powers, fairly small parts can absorb almost ALL of the r-f
power and not get very warm. 

There was a reason the old rigs used ceramic or steatite insulation in
the antenna posts and feeders. 

Unfortunately, since the bulk of ops have used low-impedance (and so
low-voltage) coaxial feedlines for many years, good hardware for high
r-f voltages is very hard to find these days. 

Ron AC7AC
K2 # 1289

-----Original Message-----

I also just finished the W1CG Low Power Balun.  I mounted the balun
inside my K2 and use banana plugs mounted on the rear panel. (in the
holes for transverter connections) This made for a very nice setup.
Internal connections were made using a short piece of RG-174 from the
antenna 2 jack on the KAT2 PCB to the balun.  The antenna is a 60 ft
doublet, center fed with 300 ohm twin lead, installed in my attic.  So
far the antenna seems to work very well. 73 
Brent