Inhaltsverzeichnis
E-646
Reception system E-646; developed and produced by Zellweger AG, Uster.
After the World War II Swiss air raid alarm network was in need of renewal, Zellweger, Uster, was awarded the contract to develop an alarm broadcasting system with the option of selective call of receiver groups.
For the air situation reporting network operated by the Flieger- Flabtruppen of the Swiss Army, the S-510 transmitter system was used to broadcast the air situation reports. In the command posts, the corresponding receiver E-646 was used.
Technical Data
- Frequency range: 2 - 12 MHz
- Decadic switches frequency selector
Power Supply
- Mains: 230 V AC mains with separate power supply NG / E-646
- Accumulator / Batteries: four 7.5 V batteries or 16 UM-1 batteries in matching adapters.
Dimensions
- E-646 receiver: 380 x 155 x 360 mm, 12 kg
- canvas bag „ZUBehör E-646“ (accessories): 460 x 290 x 260 mm; 6.5 kg
- antenna material canvas bag „ANT E-646“: 1220 x 200 x 140 mm; 16 kg
The receiver can be powered from 6V accumulators or from mains. The 6V DC voltage is used directly for valve heaters and via a „Mallory vibrator“ to generate the B+ voltage of 120V which will be rectified again.
The mains power supply accepts different voltages from 110 - 250 V and delivers an output voltage of 6V DC. This will be used to heat the valves and to feed the „Mallory vibrator“ to generate the B+, exactly in the same way as if the receiver is fed from 6V accumulators.
Only in an emergency, the receiver can be powered with plate voltage from two 60V B+ batteries.
Accessories
- As standard antenna, a long wire antenna is used: all material for the erection of a 6 m mast is contained in the antenna material bag; matching via an antenna transformer, 33 m coax cable.
- Accessory bag ZUB E-646 with external power supply, headphones, external speaker ZLS / E-646 with 25 m cable
- Remote control SDZ-646 for remote operation of the receiver via telephone line
- Test set T-646
Operation
The Zellweger Uster receiver E-646 has been introduced as alarm receiver to be used with the air attack alarm network in connection with the air attack alarm transmitter S-510.
To adress parts of the troops directly with alarm transmissions, some antiaircraft units did transmit alarm messages on fixed shortwave frequencies covering the whole country. A „call signal“ preceeded the voice message and did open a „squelch - like“ circuit muting the receiver when no alarm messages are broadcast.
All receivers come with a preprogrammed „Group address“ (GR) and eight switchable „Rufadressen“ marked with letters A - H. The selective call signal transmitted from the alarm network transmitter S-510 will open the muted alarm receivers set on the correct frequency with the correct adress A - H. The selective call signal consists of whistle tone transmitted in the upper sideband of the frequency channel which is frequency modulated and has binary coding. In standard selective call mode (RN), it's duration is 0 - 9 seconds, in short call mode (RK) only 0 - 3 seconds.
After the voice message is transmitted, a end signal (1,5 seconds) will mute the receivers tuned to the air attack warning channel.
For selective call operation, the modes switch has to set to RN or RK. In „normal selective call mode RN“, the receiver is activated only every few seconds to save battery power, that's why the selective call signal is transmitted much longer. One set of batteries will give the receiver 7 days of continuous operation.
In the „short selective call mode RK“ as well as in all other reception modes, the receiver is active continously and batteries are exhausted quickly. The modes A3, A3JU and A3JO stand for normal AM and LSB / USB reception. It's good to know, that in German language U stands for lower and O stands for upper sideband.
Some receivers carrying a sticker „K“ on the frontpanel are equipped with an additional circuit board which will activate the set on calls on all GR group addresses and all „Rufadressen“ A - H for testing purposes.
In contrast to the prototype, the speaker grill has been moved to the left part of the frontpanel. In the upper row of controls, you find the modes switch to activate A3 / A3JU and A3JO as well es the selective call modes RN (with short monitor periods and low power consumption) and RK with continuous monitoring for coded transmissions, four decadic switches to select the reception frequency from 2'000 - 11'999 kHz and the „Rufadressen“ switch.
In the lower row of controls, you find the main switch, the colume control, the connectors for headphones, external speaker, 24 V DC power and the BNC antenna socket.
The receiver E-646 can be powered from an external mains power supply, four ALN 6135-265-1751 7,5 Volt - batteries or by use of an adaptor 16 UM-1 mono cell batteries at 1,5 Volts each.
An external matching speaker can be used at a maxiumum distance of 25 meters, it has a separate volume control and a headphones jack which will switch off the speaker when active.
In a accessory aerial bag, You find everything to construct a long wire antenna to a 6 m mast, a 33 m coaxial cable to connect the antenna to the receiver and - as usual in Swiss Army equipment nearly everything to erect the antenna, even a hammer to put the tent pegs into the ground and a weight, which can be used the throw an antenna wire up on a tree or a building.
The air attack service on fixed shortwave frequencies with it's unique selective call system is not active anymore, the receiver can be used a a decent shortwave receiver to monitor Your favourite international shortwave broadcasters. It's well suited for fixed frequency operation, scanning throug a shortwave band is cumbersome as the set has only decadic frequency switches and no tuning knob. The set comes without electronic frequency memories and without all the goodies to improve reception under dufficult conditions as switchable I.F. bandwidths, notch filter, variable AGC speeds and so on.
But if you use it for that, what it was made for, the E-646 is an excellent rugged stable fixed frequency single sideband receiver.
Technical Principle
Semiconductor setup
The set is completely solid state.
Development
The air alarm message broadcasting system S-510 / E-646 was developed by Zellweger, Uster, in the years 1973/75 with the intention to selectively address different receiver groups with air alarm bulletins. The development took more time as it was the time of the transition from transistor to integrated technology.
Field use
Twenty-three S-510 transmitters and a total of 420 E-646 receivers were acquired in 1981/83; 397 of the receivers were of the normal version and 23 of the K version, the catalogue price was 15086.- Fr. (including antenna material).
From the antenna material bags ANT E-646, 280 units (at a price of 1650.- Fr.) and from the remote operation unit SDZ-646 20 units (unit price 6790.- Fr.) were procured.
In 2004, the operation of the air alarm network on shortwaves was closed down; in 2006, the shortwave receivers were sold as surplus and were temporarily sold even in Army Liq shops.