Near-field direction finder P-713, Bech NP 3; manufactured by R. F. Bech, Zurich.

R.F. Bech, a Zurich based electronics company, developed several compact near-field direction finders from the mid-forties on.

Only three sets of the compact shortwave direction finder NP 3 (P-702) were made for evaluation by the Swiss Army monitoring.

• Principle]]: Near-field direction finder Bech NP-3: Single conversion superhet
• Operation modes: A1 (BFO), AM (A3)
• Frequency range: 10.2-16.1 / 15.7-24.9 / 23.8-37.8 MHz
• Sensitivity: AM (A3) / Selectivity:

• Batteries: combined battery 126/6 V (LSA 126 6) for heaters and plate voltages

• 340 x 470 x 220 mm, kg

• Frame direction finding antenna
• Tripod
• Bussole Recta

The shortwave direction finding receiver is built using a metal cabinet of the Zellweger radio station P5 - Station, in the bottom area, there is space for the combined heating and plate batteries LSA 126/6 (which were also used in the P5 station), the headphones and spare material.

Technically, it is a single conversion superhet with three band ranges 10.2-16.1 / 15.7-24.9 / 23.8-37.8 MHz, a BFO is provided for receiving carrier signals and CW stations.

The set is equipped with one KK2 and six KF4 valves.

Single conversion superhet, IF 450 kHz.

KK2, KF4, KF4, KF4, KF4, KF4, KF4

Three sets of the NP3 short-wave direction finders were developed in 1946. They replaced the NP1 and became the predecessor of the „Bech direction finder“ NP4, a set that was introduced in 1946/7.

From the mid-1940s, the company R. F. Bech, Zurich, developed several compact short distance direction finders; three single units of the NP-3 were built.

p-713.jpg

• Bedienungsanleitung zum Peil-Abhorchgerät NP 3, KTA, 1947
• Instruction for the near-field direction finder NP 3 with diagram and parts list, Bech AG, Zurich