The transmission line or lead-in wire for a 3-meter antenna is part of the measurement. That always needs to be said as a kind of “pledge of allegiance” to the rules. Having established that fact, what approach is best for a lead-in or transmission line…. an open wire or a shielded line ?
Let It Radiate
Since the transmission line is included in the 3 meter limit then it makes sense to exploit this by allowing the line to radiate. In other words, don’t try to shield it.
Neil
Loop Holes…
And, if you use a system that is certified for use with a remote antenna like the Talking House, then you would want to use coaxial cable of the proper impedance as most systems are designed to use low impedance coax.
Or None At All
Most setups have no transmission line at all and have the output of the transmitter connected to the base of the antenna or loading coil.
RFB
Why It Is
Once the testing is complete I can set the transmitter down low connected straight to the antenna at the baseboard by the floor, but during the time of making so many measurements and changes it’s so much easier up at a kneeling position. Trying to work down near the floor is just a bit less convenient. The lead-in was only 2.5-feet.
Having a pit in the floor like an auto repair shop would really be great for working on Part 15 transmitters. Or a hole in the ground by the outdoor antenna. That could be a future upgrade.
Man found tangled in radials with only head above ground.
Fitting an 10 ft. Vertical in an 8 ft. High Room
I recall that during a visit to Monticello I saw Thomas Jefferson’s solution to a similar problem. His weight driven clock used long chains for the weights so he cut a hole in the floor so they could extend to the room beneath.
Neil
Falling Pets
Would there be cats falling from the ceiling of the room below?