When KTRB started broadcasting in 1933, their power was a meager 250 watts and was limited to daytime only operation on 740 KHz. Their antenna was long wire strung between two wooden poles behind their studios at the corner of McHenry and Sylvan in Modesto.
In 1941 they received permission from the FCC to increase their power to 1,000 watts and to operate both day and night. In preparation for the improvements, KTRB bought nearly 40 acres of property on Norwegian Ave. between Coffee and McHenry.
KTRB purchased a used 1,000 watt transmitter built by McClatchy Broadcasting in Sacramento. The transmitter had been in use at McClatchy's radio station KMJ in Fresno. In order to operate at night the station would need to operate with a directional signal which would require 3 vertical antenna poles. The antennas poles were constructed of steel well casing pipe purchased from the oil fields of Bakersfield, CA. The 30 ft. sections of pipe were welded together as they were hoisted into the air until the desired height of 296 feet was reached.
A modified pile driving rig was used to hoist each section of pipe into the air as guy wires were attached. The top section of each antenna pole started with 4 inch pipe and gradually increased to 12-14 inch pipe at the bottom to support the weight. Each pole sat on a large porcelain insulator which was affixed to a large concrete support block at the base to isolate the pole (antenna) from the ground to enable it to radiate when radio frequency current (RF) was applied.
Over 20 miles of copper wire was ploughed into the earth in a circular pattern 3 degrees apart and approximately 300 feet long at the base of each pole to enhance the signal produced by each antenna.
A technique known as "phasing" was employed during night time operations to achieve the authorized signal coverage "pattern". This technique involved all three antennas in the circuit at the same time (directional). During the daytime KTRB operated on just one of the antenna poles with the signal radiating equally in all directions (non directional).
The modified pile driver hoisting the well casing pipe sections. The original photo was altered to more clearly show the antenna itself as it was being hoisted a section at a time.
KTRB Improvements in 1941-1942
1942 the original KTRB building built on Norwegian Ave. Modesto.
KTRB's first 1,000 transmitter used on Norwegian Ave. The home made transmitter was built by McClatchy engineering in Sacramento and had been in service at KMJ in Fresno.
The 3 antenna poles in the pasture behind the building on Norwegian showing the tuning unit at the base of the closest tower.
Close-up of the tuning unit at the base of the eastern most tower. Each tower was fed by what was known as a open-wire feed line from the building and the 1,000 watt transmitter.
For several decades the government required radio, television and communication towers to be painted red and white for aviation safety purposes with red clearance lights spaced along the length of the tower and a red flashing beacon light on top. The only way to paint erected towers was by hand using mittens dipping alternately in red and white paint buckets and rubbing inch by inch by a painter (photo). Today tower owners opt for high intensity white flashing lights instead to meet the Federal regulations and modern day towers with the new clearance lights need not be painted the traditional red and white.