Topband: Using 4 - 6 elevated radials in lieu of 120 buried wires

[Jim Brown]

As a student, I had co-op jobs both with WLWT and with Pete Johnson, a 
broadcast consultant who, with Carl Smith (CREI) wrote the FCC technical 
Rules after WWII. I also toured the WLW and adjacent VOA site with my EE 
class my senior year.

I'm pretty sure that the 500kW rig is no longer licensed, although they 
were demoing it into a dummy load when I toured (1964). The dummy load 
was something watercooled in front of the TX building. The modulation 
xfmr sung as loud as many speakers. It's my understanding that the 500kW 
rig was only on the air pre-WWII, but I could be wrong.

Broadcast stations are designed with two concerns, the dominant one 
being groundwave coverage, which primarily depends on soil conductivity 
over the entire path to the listener. One of the things I did in Pete's 
office was plot field strength contours on aeronautical maps using 
nomographs within the FCC Rules and the Commission's Ground Conductivity 
maps.

The secondary concern, for stations licensed for more power, and 
especially for what were then "Clear Channel Stations," was sky-wave. 
And that's part of the other thing I did in Pete's office -- 4-5 of us 
EE students sat around a boardroom table with slide rules, math tables, 
and very large accountant's spreadsheets (think 20-30 columns) doing the 
math to compute the patterns for every five degrees of Az and El for the 
multi-tower directional arrays needed to squeeze new stations into a 
band that had been full for more than a decade (probably from before WWII).

That adjustment to improve coverage of Columbus would have been for 
nighttime. The WLW site is roughly 1/3 of the way between Cincinnati and 
Dayton, a bit east of I75. Where I grew up in WV, WLW was our NBC 
station, probably 100-120 miles as the crow flies, and we listened on a 
pretty good table radio (my grandfather was an EE). This was the '50s.

In those years, WLW and (I think) WOAI were the only 50kW clears with no 
one else on their frequency in the US. Something like 30-40 years ago, 
clear-channel stations were far less exclusive.

73, Jim K9YC



On 1/5/2024 12:57 AM, Ken WA8JXM wrote:
> Supposedly the half megawatt transmitter is still operational and licensed.