Radio officers category marine radios electricity for beginners


The Polish OK-102 is one of the less known maritime main receivers. 850 gas block The OK-102 was a derivative of older OK-2 (OK stands for: Odbiornik Komunikacyjny – eng. communication receiver). As some other receivers the old OK-2 was derived from pre-war National HRO that was considered one of the best receivers of its era. The diagram looks similar, uses the same principle but the overall receiver design is quite different. Instead of precise micrometer scale tuning and changing whole tuning coil set during band change (a HRO “trademark”), Polish receiver was tuned by a two stage reduction gear and bands were changed by switching fixed coil sets. There was neither bandspread tuning nor noise limiter circuit.

OK-102 was designed by R.Żebrecki and made by MORS*) factory from 1958 to the middle 60s. It was one of the very few valve maritime receivers that could be powered from 24V battery without voltage converter (for the anodes as well, jolly good idea!). The old OK-2 used loctal valves (eg. UCH21, UBL21) and newer OK-102 used noval valves (ECH81, EF85). Anyway the circuit still resembles the old and good HRO.

The first stage – the RF amplifier – was made with single EF85 valve (HRO had two 6D6 pentodes), second stage was the mixer and oscillator on ECH81. Two stage pentode IF amplifier used ECH81 valves (triodes were used for BFO oscillator and audio preamplifier), detector used Polish germanium diode DOG58 (similar to 1N68, the HRO used diode from 6B7 valve). Intermediate frequency was 660kHz (much above 500kHz band to avoid interference, the HRO used 456kHz and it was probably too close). OK-102 had single crystal narrow filter for CW almost the same as HRO had. It was simplified and lacked “phasing” control though.

*) MORS (pol. mors – eng. a walrus – but the name was derived from Morska Obsługa Radiowa Statków – eng. radio service for ships) – was a small company that made and serviced maritime radio gear. when was gas 99 cents in california In the 60s/70s MORS was the only company in the Comecon (Eastern block) countries that produced electronic gear for yachts and small vessels like the taffrail log, electronic windex, and echo sounder. It grew and split and later became bigger RADMOR company (the RADMOR name had also something to do with maritime business as it was derived from RADio MORskie – ang. maritime radio). RADMOR still exists, produces rugged VHF/UHF radios for military and professional use. Morska Obsługa Radiowa Statków MORS also exists as a maritime radio service shop within Remontowa shipyard that services GMDSS gear in Gdańsk.

This masterpiece of old tube technology is quite rare comparing to Marconi, Mackay or even Dansk Radio (the Elektromekano brand). It came from a Swedish company „Standard Radio & Telefon AB” in the 50s, it was installed on three Polish vessels including s/s SOŁDEK callsign SPCJ (, now a museum ship. You can see this ship as a part of National Maritime Museum in Gdańsk, Poland. Unfortunately none of the original radio sets onboard are in working condition. A group of enthusiasts wanted to restore main transmitter and one of the receivers but the process is very complicated as of now.

There were also three sister ships that had similar radio setup: s/s BRYGADA MAKOWSKIEGO/SPCN (written off in 1979) and s/s JEDNOSC ROBOTNICZA/SPCK (written off in 1978). It’s Standard Radio ST1200 *) that covers maritime bands 4-6-8-12MHz (A1/A2), telegraphy on whole 500kHz band and AM coastal telephony on 1,8MHz band. electricity demand Therefore its range and modes were more than adequate for voyages all over Baltic Sea or the English Channel. This is where s/s SOŁDEK sailed.

It’s comprised of separate modules: exciter and final stage of HF CW transmitter, MF AM coastal telephone transmitter, 500kc main transmitter, power supply and A2/A3 modulator for W/T and R/T. It uses standard chain on HF W/T: crystal oscillator, frequency doubler/tripler chain, separator, driver and C-class power amplifier. One stage of the doublers is bypassed on lower bands. MF R/T is also crystal controlled, uses standard principle with Class-C PA, anode modulated. The 500kc main transmitter uses free running oscillator. electricity 101 pdf The HT is in the kilovolt range. Power supply requires AC converter (a dynamotor perhaps) and separate voltage regulator because many vessels of that time used DC power supply. The s/s SOŁDEK/SPCJ was no exception – it was a DC ship.

Exciter of the shortwave W/T transmitter. It’s crystal controlled – 6 pcs of 2MHz crystals can be used (on SPCJ only three of them were inserted). Frequencies used: 4178, 4201, 4222 ; 6268.5, 6301.5 , 6333; 8358, 8402, 8444 and 12537, 12603. Third crystal on 12MHz after doubling and tripling was 12666 MHz therefore outside of the usable 12Mc maritime band in Poland.

Signal from oscillator is fed into the doubler that works also as a tripler for 6MHz band. Changing the band swich position bypasses one of the doublers in chain. gas monkey monster truck It’s similar to the doubler/tripler chain used in Marconi Oceanspan transmitter. Then the driver stage is tuned to resonance. All voltages and currents can be measured using a selectable meter. Cathode current of the last driver stage is measured by a separate meter. Tuning procedure: set a proper crystal to be used, set the band switch to position depending on the band and tune doubler to resonance within band (cathode meter should deflect some, tune for maximum deflection). Then tune final stage, then tune the driver stage to maximum deflection and correct doubler tuning if needed. Take care of maximum reading of anode current in the final stage.

VEB Funkwerk Dresden was a publicly owned company (VEB) in the city of Dresden during the times of the former DDR (East Germany). The company was founded under Russian occupation immediately after WWII, in 1945, and was initially known as Radio H. Mende & Co. Dresden. In 1948, it became a Volkseigener Betrieb (VEB) and was renamed to VEB Funkwerk Dresden . electricity and magnetism study guide As the company was also part of the RFT consortium, it is also known as RFT Funwerk Dresden. Initially Funkwerk Dresden contentrated on the production of radio receivers for the domestic market, with bulk production starting in 1951. In 1962, the production of radios is cancelled and moved completely to Stern-Radio Staßfurt. From that moment on, the company concentrates on the production of measuring equipment and radio communication systems.

A few years later, in 1972, the name ‘Otto Schön’ is added to the title and the company becomes known as VEB Meßelektronik ‘Otto Schön’ Dresden. This name lasts until the company is merged with the large VEB consortium Robotron in 1979, after which the name is changed to VEB Robotron-Meßelektronik ‘Otto Schön’ Dresden. On 30 June 1990, after a variety of problems in the supply chain, the company was dissolved in the light of the reunification of Germany .