[Milsurplus] Japanese radar on Corregidor

Tue Sep 4 00:41:20 EDT 2018

On 3 Sep 2018 at 21:19, Tom B wrote:

> 
> Hi Joe,
> Yes, it is a RADAR, Navy Model 3 Mark 1 Type 3.  See 
> http://www.yokohamaradiomuseum.com/radar2.html
> I have one of the receivers in my collection.  It operates at about 150 MHz.
> 
> Tom Bryan
> N3AJA

A translation (somewhat poor) of the Japanese documentation on that page.

1) This equipment is a small portable anti-aircraft warning radar used on land and ships. 
Because it was light and convenient to use, in naval vessels it was equipped on almost all 
ships including naval vessels and submarines.

2) Effective distance: flight 100 Km, single machine 50 Km
Frequency: 150 MHz band
Transmitting peak output: 10 KW
Measurement method: Maximum sensitivity method
Distance accuracy: 2-3 Km, Angle accuracy: 10 °
Equipment outline
Transmitter: Oscillation T-311 x 2 (PP), modulation pulse shaping RH-4, amplification 
T-307, modulation T-307
Receiver: Superheterodyne system (11 tubes), high-frequency two-stage (UN-954 x 2), 
mixer (UN-954)
Local oscillator (UN - 955), intermediate frequency 5 stages (RH - 2 x 5), detection (RH - 2), 
low frequency amplification (RH - 2)
Instructor: A scope method
Power supply: Single phase 110 / 220V AC power supply
Antenna: dual transmission / reception, half wavelength horizontal 2 rows 4 stages (land 
installation type)

(Note: I find it very odd that the tubes used in the "front end" of the receiver are US made 
954 and 955 "peanut" tubes. These were Top Secret at the beginning of WWII)

3) Transmitter: The transmitting part is a self-pulsation method with triode T-311 push-pull. 
The transmission frequency is adjusted to one wave of 145 to 155 MHz at the time of factory 
shipment. In the modulation, a pulse waveform is generated by the differentiating circuit of 
RH - 4 based on the synchronizing signal from the indicator, shaping and amplifying at T - 
307, and pulse - modulating the oscillating tube at the next stage T - 307. The power supply 
section generates for the oscillation tube T-311 supply voltage 7,000 V, T-307 supply 
voltage -1,200 V and others, high pressure rectifiers in diode tube K-250 and others with 
selenium.

4) Caption under photo on the left. The left transmitter, the upper transmitter, the lower 
stage power supply, the right receiver, and the transmitter have no operation part other than 
the power supply switch.

5) Caption under photo on the right: Transmitter, upper stage oscillator, oscillation is T-311 
push-pull, lower stage modulator, two vacuum tubes RH-4 and T-307.

6) Caption under tube: Oscillation tube T-311 on which the heater has been energized, light 
is bright orange.

7) Caption under photo to the left under the T-311: Power supply unit, vacuum tube is high 
voltage rectifier tube K-250.

8) Caption under photo to the right under the T-311: Transformer for generating an anode 
voltage of 7,000 V at the center.

9) Receiver: This receiver can receive variable transmission of 145-155 MHz with a spur 
heterodyne system of high frequency two stage and intermediate frequency amplification 5 
stages. Two high frequency amplification UN - 954, frequency mixing UN - 954, local 
oscillation UN - 955, intermediate frequency amplification RH - 2, detection RH - 2, low 
frequency amplification RH - 2.

(954 and 955s ??? !!!. Gee...)

10) Caption under photo: Left receiver, right receiver power supply

11) Caption under photo of paper chart: Receiver frequency table

12) Top view of open receiver: Antenna tuning inside, tuning of frequency mixing section, 
local oscillation circuit tuning, output adjustment, handset terminal from the right front of the 
panel from the front of the receiver. Internal front row is front end section, rear row is 
intermediate frequency amplification, detection, signal amplification section.

13) Caption under photo of receiver power supply: Inside the receiver power supply, 
vacuum tube (?) rectifier KX-5Z3, constant power  discharge tube VRA65/80, VRB135/60.

14) Receiver RF section: Receiver front end part, high frequency amplification 1 step UN - 
954, high frequency amplification 2 step UN - 954, frequency mixing UN - 954, local 
oscillation UN - 955 from the right.

15) Scope: The waveform display of this 13th electricity search is the A scope system, the 
distance to the target is displayed on the horizontal axis on the Cartesian coordinate of the 
CRT and the intensity of the reflected wave on the vertical axis. In this electric search, a 
synchronous signal generator and a marker signal generator for indicator distance 
measurement are built in the indicator.
Abstract: Instruction machine No collection

16) Caption under scope display: No. 13 Electrical search indicator (A scope system) 
Concept diagram of target captured image
Waveform downward on the horizontal axis is a ranging marker with a scale of 20 km, 
around 130 km wide reflected waves are captured aircraft large formation, around 75 km is 
small formation, noise on the horizontal axis is noise.
(Illustration Source: HP Naval Radar Tsubasa Grass)

17) Caption under CRT: Cathode ray tube for indicator BG-75A

18) Spare parts box: Spare parts boxes are two-tiered and contain many transmitters, 
receivers, various spare parts for power supply. Writing of the lid is "Tentative No. 1 No.1 
wave radiator trunk type 3 type supplementary item box"

19) Caption under spare parts box: Spare part box. 

20) Caption under photo of rod: Measure the standing wave of the feeder line using a 
measuring rod and a neon tube. Length 28 cm made of ebonite.

21) Caption under double-photo of open box: Spare parts inside box.

22) Antenna: The main electronics searching antenna is used for both transmission and 
reception, half wavelength, horizontal 2 rows and 4 steps, with reflector. The land antenna 
should be rotated by human power, and the aircraft antenna should be rotated manually or 
electrically.
For a ship The feeder line and the antenna are connected by a high frequency transformer 
at the rotating part.
Electric rotation type three element two stage Yagi type antenna was used for submarine 
equipped No. 13 electricity search.

23) Caption under photo of antenna on the floor: No. 13 electric wire searching antenna, 
power feeder, reflector not included

24) Caption under photo of antenna: Showa 18 Chiba prefecture Taito test site installed No. 
13 Electro Search Land Aerial.

(It is clear from this photo that the photo which was shown earlier in the question about the 
installation on Corregidor is of this type of antenna lying on the ground pretty much 
destroyed. The same lattice mast and some elements.)

25) Caption under last photo on the bottom of the page: 401 Three Elements for Electricity 
Search No. 13 installed in a submarine bridge Two elements of Yagi type antenna and 
upper stage antenna of two stages are missing.
The E-27 receiver of the VHF radar wave detector (so-called reverse search) that is 
installed diagonally to the right of the Yagi-type antenna for No.2 No. 2 type 2 microwave 
electric probe for No. 2 No. 13 Racket type antenna for.

Ken W7EKB

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