Topband: Air Wound Coil

[W7RH]

Per the following added comments.

> Me too.
>
> Or the inverse as I did, cut my T for the low end of the band. Then 
> three series capacitors with PCB relays to short each individually 
> (none, 1, 2, or 3) yielded nearly full band coverage <1.5:1 swr.  My T 
> is 85' to top and a 50:25 ohm TLT is a close match, then the capacitor 
> stack follows.  Caps and relays fit in a weather tight plastic box 
> about 3x5x8".  Of course the resonance resistance and capacitor values 
> depend 

I did exactly this for an 80/75 meter dipole.  Worked perfectly.
I am planning to do this same thing for my 160 meter vertical
when I get around to it.

Rick N6RK


Transmitting type capacitors are expensive and hard to find these days. 
An air wound coil on ABS using copper tubing with Un-Un matching 
transformer will run you about $25 when built by oneself. The advantage 
of tuning high and using 4-5uh coil with Un-UN is the antenna is at 
electrical ground all of the time. This allows cheap relays and prevents 
pitting by static discharge. In this way your gas discharge radio 
protection only needs to function on induced impulse voltages saving you 
from singing arc plugs and additional costs.


Bob, W7RH

-- 
W7RH DM35OS


It has become appallingly obvious that our technology has exceeded our humanity.

Albert Einstein