plugs secured against accidental release. Box with a spare and backup Parts included: Set gas tight nickel cadmium batteries, PKJ 832 khz, 7 tubes, 9

Transcription

1 Receiver R5A Receiver 5A was military, field, portable, small shortwave communications receiver with battery powered. May be used stable - fixed line and mobile operations. The working range is from 1.5 MHz to 22 MHz. The first report in the documentation of its launch D is from Production Year 1962nd Development and production started in "VEB Entwicklungswerk-Funkmechanik Leipzig " (Developmental race - Radio Technology Leipzig former. NDR). To Czechoslovakia was supplied with descriptions in English, our normalized samoupínacími military jacks and some TESLA components and METRA. In our Army has served for many years. A few years ago was the army transferred to the radio clubs. Amateurs acquired at a bargain price (around 300 crowns) receiver, which, if it was okay, he surprised her parameters. His MHz ranges are: 1st to 3.75 second Third from 3.6 to 5.8 The fourth from 5.6 to 9.2 5th 8.8 to 14.3 Sixth from 13.8 to 22.5 The receiver allows reception of signals AI A2 and A3 (according to CCIR) through complex třísegmentového switches operation. It is ur-chen for continuous operation with minimal heating components. To receive A1 and A2 is used built Tone filter. When receiving AI is used dual mixing. Furthermore, the built-in voltage protection, so it can work in the immediate vicinity of the transmitter, or in an environment with the electrostatic field. Own Power Supplies - Batteries not included receivers are located outside the housing and with a receiver connected by cable. Accumulators B1 and B2 enough for its capacity 24-hour continuous operation. If he works a stationary receiver, is fed from a foreign subsource with greater capacity. Precision mechanical gear tuning combined

2 with a sufficiently long (box 190 x 32 mm) scale, allows very fine and coarse Tuning and subtraction. Fine-tuning is done mechanically, pushing and manipulating recessed screw on the right next to the scale. The principle is similar to that of the receiver R4. For coarse tuning is slight backlash, for fine-tuning backlash he is not. Ratio transfers for the fine tuning of 720: 1 (!) and for coarse tuning 11.1: 1st At lower received Frequency is the distance scale intervals 10 khz, the higher frequencies of 20 khz to 100 khz. The actual scale on strip 10 mm wide is applied on a light mint-nem white; glazed and reflect light, glare (if necessary) is illuminated pressing a button. Lighting Bulb ("Sufitka" 12 V / W 3) is moved - is entrained - Above the scale together with a pointer, so that when Tuning created an interesting and intimate lighting. Input circuits, ie RF Ampli, mixer and auxiliary oscillator are located on a swivel, a covered and shaded bubnukaruselu Comply with Ii lubricating prescription, then goes Mechanics "like butter." There is a remarkable 'Eternal' drive from the small scale fosforbronzového band, which currently carries stupnicový pointer with lighting. other Parts of the receiver can be easily removed. Rain receiver design is made Alloy. Panel and cabinet are sprayed hammered finish with olive green shade. Dimensions: Width 370 mm, Height 153 mm and depth 320 mm. Receiver Weight without accessories is 13 kg. Temperature resistance It is from 25 C to 40 C. Requirements for quality receivers (resistance, vibrations, shocks, falls, etc.) They were determined by specific and general standards. Supplied accessories were: long antennae wire and rods (Bond), screwdriver and key, two headphones with an impedance of 4 kilohms, Cabinet sources with rechargeable battery and two the cables with "air" šestipólovými

3 plugs secured against accidental release. Box with a spare and backup Parts included: Set gas tight nickel cadmium batteries, PKJ 832 khz, 7 tubes, 9 tranizistorů, 6 bulbs, neon 3 and 3 control knobs. On the top left side of the receiver cabinet bracket is attached to the rod antenna. On the front panel, top left to find: terminal antenna jack on insulator the RF ceramic, ground terminal, intercepting Holder ear (be careful here let's take the bottom bracket, otherwise difficult to obtain from him!!!). Further, these are three flexible rubber sealing cover but not with other production batches ochráněná buttons and control dial illumination voltmeter the range of 1.25 V and 4.2 V. Middle of the scale with a screw on the right for fine tuning mechanical scale receive frequency. In the bottom panel, the fine and coarse tuning scale in one the knob being pulled closed by jack headphone connection. Another embodiment has the special Round dash six pole sockets pérovaným with lid (Sach.Nr ). About the middle of the range switch, turning carousel, the right of the switch operations, further adjusting the volume knob (or handheld RF amplification ") with pull switch and foursquare miniature control voltmeter product METRA Blansko, (22x22 mm, sensitivity 500 ma). Closing the lid, the receiver automatically shuts down pushing the lid on the volume knob. B1 separate battery powers the glowing tubes 1.2 V / 0.4 A second single battery B2 series parallel connection of 7.2 V / 0.15 A supplies circuit boards mounted transistors, ie second MF amplifier, audio amplifier and voltage měničtransvertor, at whose output is positive anode voltage of 60 V for the tubes. RF stages are fitted with tubes, the second mixer, AF amplifier and transducer are 9 pieces Ce tranzis

4 tors PNP and another six diodes. From vacuum tubes were used then the former. NDR modern ' plant "Werk VEB Röhrenwerk RWN Neuhaus' announced in 1956 subminiaturnf glass tubes (oval shape (9.8 x 7.3 mm, length 38 mm) Battery pentodes with five wire terminals, long 32 mm. (It is interesting that the equivalent tubes in the US since the device osazovaly 1941) for controlling the degree of it was for DF97 Mixer (mixing with acceptable slope and with an approving glow voltage other tubes), in which for obtaining a relatively large negative bias voltage, requiring max. Mixing slope, boldly used high leakage biasing resistor R6 2M2. These battery directly heated tubes It may be small glow voltage of 1.25 V and heater current of 0.05 A to 0.1 A, but the even small holiday glow tolerance zone voltage. Therefore requiring incandescent battery nickel cadmium battery with discharge characteristics gently and liberally declining as sufficient capacity. Decreases when voltage incandescent, electron loses its power, which is immediately knows (because the receiver has control voltmeter) přežhavení "tweaks" receiver parameters but again significantly shorten the life of the tubes. This is an important lesson for young people "Semiconductor amateurs" owning 5A who no experience with battery tubes. Of the types of transistors are PNP or OC811 OC816, OC821 diodes OA645 and OY102 (or GY102, or TESLA 43NP75). Let's look at a diagram of the receiver group detail: the antenna is unbalanced nízkoohmovým 70 ohm input is fed accepted signal (through multiple antenna filtrodlad'ovač

5 L1 to L3, C1 C6 whose malting frequencies are not listed on a socket in isolation disposed on the sub panel beside Ro2, the input antenna coil carousel. Against damage to the input circuitry by electrostatic charge (so common in receiver LAMBDA) input is protected by a miniature glow lamp GL1 Type BS Important: on original Schema is a mistake (!) in the circuit Protective lamp La2 (small "sufitka" 40 V / 10 W) between the antenna and the antenna winding filter. According to the diagram, the connections between the terminal labeled "2" and the output of the antenna filter must to cancel; Bulb is it short circuited and outlet "2" then connect to ground. The test apparatus, which was available to the light bulb connected LA2 inverted: terminal "1" input coil carousel It is directly connected to the antenna filter outlet "2" is led to a light bulb and a second terminal the bulb is connected to ground. Input tuned RF amplifier is equipped Rol DF669, DF97 mixer with RO2 and auxiliary oscillator with RO3 DF668. their circuits placed on the carousel, they are easily accessible for tuning windows in the housing. Mixer He receives two signals: the received goes to the first Grid DF97, a second auxiliary oscillator RO3, which oscillates about the MF frequency up to the third Grid DF97. RF circuits are all apart custom capacitor (Trial 3 x 9 37 pf) still a little trimmer potentiometers 3 15 pf, the oscillator "Shortening" capacitors with tolerance 2% and understandably coil with ferrite cores. The plate circuit mixing tubes a first primary winding of the MF transformer, tuned to a frequency of 900 khz. Followed by MF three stage amplifier tubes RO4, 5 and 6 3 x circuits DF69 and bonded impedance adapting capacity inductive coupling Hence the constant spreading of the transmitted bandwidth: at A2 and A3 of 4.5 KHz ± 500 Hz. Last AF transformer with winding SP28 and Sp29 has demodulation

6 AM circuit with GE diode GR2 OA645 a source of control AVC voltage diode other Grl OA645. LF signal is supplied to the volume control Potentiometer P2 50 l / log. Further the signal is fed through a complex třísegmentovýtřípatrový Switch to the input audio preamplifier a tone filter (1kHz bandwidth of 200 Hz) and further amplifier (2 x OC811 and OC816) and symmetrical end audio amplifier (2 x OC811 and OC816) with remarkable subminiature an output transformer with output an impedance of 600 ohms. Its frequency characteristic is equal to 300 Hz to 3.5 khz distortion at around 0.5%. Sizing Generator Generator Generator brands is equipped with vacuum tube Ro7 DF97 (second mixer) with a frequency stabilized PKJ KRL 932 khz (Type QDS19) involved between the first and second grid 97. The signal DF is taken from the "anode" secondary coupling the coil winding in position SP30 Operating switch "Calibration" to zero beat (black triangle) and brought to diode GR5 (OA645). Despite its small capacity 10 pf C3 signal is applied to the antenna input filter. Thanks diode bias arises frequency range number of harmonic multiples PKJ which the receiver is calibrated. With increasing the frequency range of the receiver rises the number of calibration points. First range is one point on the last screen then 10 points. Because they are spaced apart nearly one MHz (932 khz), we can not could be wrong. Scale tune mechanically screw. Receiving the unmodulated telegraphy A1 does not Classic BFO. MF frequency the last MF transformer 900 khz it leads to the pin "M2" samokmitajícího mixing electronic and Ró7 DF669, using capacitive divider C105 and C106. Its oscillator We are, as we know, stabilized RKJ 932 khz.

7 MF difference frequency 32 khz the second MF in the receiver is conducted on a two step transistor amplifier involvement common emitters of Tr3 and TR4 (s OC816). MF transformers have a fixed capacitance bond. TRS5 the auxiliary oscillator oscillating at the frequency 33 khz. Both signals 32 and 33 khz khz are kept to a diode County 6 (OA645) Third mixing. The resulting difference frequency audible beats 1 khz is passed through the operational Switch on the C125 and also on the audio amplifier. So avoid entering into the 32 khz audio amplifier, is incorporated in the circuit a suction circuit Serial debugger tuned to 32 khz (SP36, 22 0). When receiving AVC A1 is disconnected and RF management ("Volume") is done by the other tandem Potentiometer R54 / 100) on a common axis with potentiometer R52 (50 k log). Changing the negative bias voltage for electron tubes Rol 4, 5 and 6. This is a relatively wideband input bandwidth 9 khz, converted to another mixer and a second amplifier MF 32 khz with a bandwidth of 1 khz ± 200 khz. As shown practice, this method has proved to A1 transformation. Power supply Drive transvertor is current involvement: oscillator transistor Trsl and TRS2 (2 x OC821), the voltage doubler GR3 and GR4 (2 x DY112, bebo TESLA 43NP75). Details of the inverter will be described below in Description Receiver R5 A1 at about 1 mv at A2 and A3 of about 4 mv or better. Relative to noise ratio 10 db modulation depth 30% HF for at load resistance 600 ohms. Frequency stability at the receiver 25 C to 40 C is or less. Selectivity when receiving an A1 at 10 Mhz about 50 db at frequencies above about 10 MHz 35 db

8 Figure 3: Group scheme receivers 5A, R5P and EKB 1) The input filter, protective lamp La2, protective glow GL1 and RF amplifier Ro1 DF669, 2) mixing stage Ro2 DF97, 3,4,5) of the first amplifier MF 900 khz, with RO4, and Ro5 RO 6, 3 x DF669, 6) AM demodulation stage and voltage source AVC GR1, GR2-2 x OA645, 7) Sizing Generator harmonics PCL / KR1 / s Ro7 DF669 / u switch and LED traffic GR5 A645 8) tuned auxiliary oscillator with RO3 DF668, 9,10) second mixer with RÔ7 DF669 / PK) 932 khz / 11,12) a second amplifier MF 32 khz diode GR6 OA645, 14) The beating frequency oscillator 33 khz TRS5 OC811, 15) nf preamp with tone filter and output stage / 4 x OC811 and OC816 / 16) voltage converters - transvertor V / 60 V - Trsl, TRS2-2 x OC821, Bal) Glow Battery 1.2 V, Ba2) battery 7.2 V power converters, the latter MF and LF amplifier

9 Fig. 4: Back of receiver 5A, removed from casing 1.2) voltage converter, T RSL, TRS2-2 x OC811, 3.4) MF amplifier 32 khz Trs3, Trs4-2 x OC811 5) Oscillator 33 khz TRS5 OC811, 6), the last stage MF amplifiers 900 khz - RO4 DF669, 7.8) MF amplifier 900 khz - Ro5, RO4-2 x DF669, 9) approach to RF tuning circuits 10) shielding bulkhead 11.12) audio output stage Trs8, Trs9-2 x OC811 / OC816 or 2 x /, 13.14) audio preamplifier Trs7 - OC811 / OC816 / 15), second mixer, controlled oscillator PCL / KRL / 932 khz - RÔ7 DF669, 16) of the carousel cover, 17) tuned RF preamplifier RO1 - DF669, 18), first mixer Ro2 DF97, 19) auxiliary oscillator RO3 DF668 Page 15 rebuilding (changer, audio amplifier does not make difficulties. Individual parts are easily accessible, just PKJ KRL is "drowned" under vacuum tube Ró7 beware Damage tubes pumping tube, during disassembly. Another danger is thin glass flasks tubes requiring gentle and attentive treatment. The meter can be In addition, and impressively placed in a special

10 housing outside receiver. It is involved in the circuit RF zesilovč Rol, with resistance R5. Passes a conventional moving coil meter with 500 citlivoustí ma to 1 ma. From the catalog data easily we find that the original Ge transistors can enliven exchange for older Ce transistors TESLA NU, CC, etc. Other papers, comments and experiences receiver 5A which are common for EUB receiver are listed at the end of the article. R5P is the embodiment of a portable receiver belts, lifting frame and lock. EKB the designation of receivers in the former. People's Army GDR. EUB the military, field, small and portable communications Receiver battery powered, operating in the VHF range. It is designed for reception AM and FM frequency bands from 20 MHz to 65 MHz, divided into six subbelt ranges. Building on a receiver R5. Production year The development philosophy and manufacturing race all with the same receiver R5. His dimensions, weight, appearance, structure and the controls are exactly the same. So, what was written about R5 applies only to a small exceptions (range, mixing and FM reception) also EUB receiver. It can be according to standards CCIR listen operating modes F2, F3 and A3 plus calibrate scale generator PKJ controlled. It can be used as portable and stationary traffic. Especially It is designed to receive FM signals. And how it is expressly stated in the AM reception It is transmitted bandwidth of 15 khz. Must thus allow for increased levels of noise and interference. Battery capacity BI and B2 allows continuous operation at maximum length of 18 hours. Stationary Traffic can be powered from the next foreign sources, without having to own remove the battery. These batteries are stored in a special box and are composed of 18 pieces

11 gas tight nickel cadmium batteries, each with a voltage of 1.2 V and a capacity of 2 Ah. Foreign stationary batteries B1 has a current consumption of 0.6 A at 1.2 V battery B2 has a second collection 0.2 A current at a voltage of 7.2 V, with a minimum capacity 4 Ah. The traffic receiver EUB and R5 They are therefore needed two batteries: B1 for heating and second tubes B2 to power transistor Inverter transvertor (7.2 V / 70 V) and for audio power amplifier transistor. Wiring batteries in Figure 7. The receiver is supplied accessories: Bond spring antenna, long wire antenna, screwdriver, wrench Matkov, two headphones, box with batteries, jumper cables and a carrier frame. Weight 1 3 kg, operates in the temperature range from 25 C to 40 C. MHz ranges are: 1st 19.0 to 25.0 Second from 23.5 to 31.0 Third from 28.5 to th th Sixth from 51.0 to 67.6 In principle this is a double superheterodyne FM mixing, with particular cejchovacím PKJ generator that still spreading transmitted bandwidth without AVC, BFO and without RF manual control. RF stages are equipped with subminiature battery powered tubes, AF episode and transverter are fitted Ge transistors PNP. It is therefore a hybrid installation. Nasymetrický antenna input and the input impedence 70 ohms. From the tubes are pentodes: 3 x 6 x DF668 and DF669. For semiconductors are Ge transistors OC811 4 x, 2 x OC821 and RF diodes 2 x OAA646 (Ge) and two powerful Ge diode OY102). Further, these are the two crystals KRL 7.6 MHz 23.1 MHz and Kr stupnicová bulb "Sufitka" 12 V / 3 W directly to the lower part receivers are spring holders substitute tubes 2 x 2 x DF668 and DF669.

12 The antenna is fed through a capacitor Cl 1140 pf and ceramic insulated socket odledovač the input filter to sleep, SP2 and SP3 (whose frequencies are tuned not shown). There used to protect against static hub with glow lamp and a protective bulb as the receiver R5. Inlet tube, tuned RF amplifier Rol DF669 amplifies the signal for the next stage mixer with RO2 DF669 (not for DF97 As with R5), whose relatively large negative bias control grid is tapped into divider voltage (R5F6 and C139) connected to the power voltage 7.2 V. The three point auxiliary oscillator tube RO3 DF668, involved as a triode (G2 and anode connections). Receiver Tuning Trial is 3 x 25 pf. Injection of oscillator It is fed through a capacitor C53 6pF to control the grid mixing tubes together the amplified signal received vacuum tube Rol. Mixing generating a first frequency MF 10.7 MHz, one step further amplified vacuum tube amplifier with RO4 DF669. High frequency MF guarantees a good distance mirror frequencies. As a second mixer works Ro5 DF668 samokmitající mixer. PKJ KRL 7.6 MHz is connected between the gl and g2 tubes. In the anode circuit involved MF transformer tuned to the frequency 3.1 MHz. Followed by a three stage MF amplifier tubes RO 6, Ro7 and Ro8, all with DF669, fixed inductively kaoacitní bond (C81, C90, C97, C104, and Cl 13) so the width of the transmitted bandwidth is constant. When receiving A3 is the final anode voltage MF amplifiers RÔ8DF669 disconnected Use Switch operation Schl and holds the position gl anode diode AM detector. From the MF circuit Sp31 is removed demodulated AM signal for nf transistor amplifier with no tonal filter. Has transistors: 2 x OC811 preamp and 2 x OC811 push pull output stage in

13 with miniature output transformer secondary impedance of 600 ohms. At listening to F2 and F3 gets the tube Ro8 Full voltage (g2 and anode) changeover switch Schl and works as the last stage and MF amplitude limiter, consisting of dvojitéo MF transformer. The second winding SP33 discriminator is connected with diodes Grl and GR2 OAA646. Nf signal is transmitted again through Schl a simple potentiometer to log R with pull switch and further to the audio amplifier. Since there is no manual RF control, potentiometer R30 simple. AF amplifier and transvertor are walkable with R5 receiver, just it gives a higher output voltage at 70 V. The receiver does AVC; Working negative biasing the tubes is obtained by passing the grid power to leakage resistance. Sizing Generator Generator brands It is equipped with vacuum tube Ro9 DF668. It is managed PKJ Page 16 KR2 a frequency of 3.1 MHz, which is connected between the first and second grid, so burdened a minimum. Anode works as a separator degree. The generator is actuated switching Schl switch and turning it glow. Heater circuit tube is close to RÔ9 tubes suppression circuit L / C (DR10 and Cl 20). The generator output is fed through a small capacitor Cl 19 (IPF) for the input circuit carousel otherwise nazapojený touch "2". Calibration marks are labeled on a scale small black triangle and are separated by away 3.1 MHz, the number two brands on the first screen and the last four sixth range. The scale has an almost linear division is clearly legible and lit (press button). The distance scale intervals is 50 khz for the first range and 100 khz to the last screen. Operating switch has three

14 position: calibration, A3 and F3. For both receivers underlined danger connect both power supplies Bal and Ba2 (1.2 V and 7.2 V). The reason is obvious: the effort to limit noise generator inverter to a tolerable Peace. It must be said that the drive is not absolutely interference suppression, interference is particularly noticeable when reception of weak signals. Generated Voltage converter with frequency of about 500 Hz, which is in a closed shielded space, a course too far from sinusoidal course, so it has good conditions for the formation of non sinusoidal harmonics. Emitters inverter, TRS5 and Trs6 (OC821) are connected directly to the positive battery voltage B 27.2 V, and only then at the shortest connection drive cover and thus to ground receiver. So interfering signal is not able to produce longer conductor (such as a cable from the battery) passage Current converters and other reinforcements. This circumstance is the construction of baffles somewhat overlooked. Of course, the inlets BI and B2 voltage at each grade circuits have their filter circuits L / C. The output Inverter is performed using a doubler rectification voltage and properly filtered. Electric properties are very close to the receiver 5A (sensitivity, etc.). Collectors and ordinary listeners let disclosed Receivers in their original condition, despite considerable difficulties with batteries. Daredevils experimented rectifier. Because the drive is still stubbornly echoed, particularly in quiet environments and when weak received signals, was simply replace rectifier supplied from the network. For the case best suit From a drawer a legacy network transformer Receiver TESLA MINOR or TESLA Vacationers (2PN 98002). Its secondary voltage of 65 V is normally rectified, filtered and as adjusted series resistance size 60 V. The second secondary voltage 2 x 1.4 V

15 It requires two way direct the rich capacitive filter. Wire rheostat connected place the filter in the filter resistance rectifier set dynamically Glow by built in voltage resistance the desired value of 1.2 V to scale mark. Voltage for LF and MF amplifier (for R5) is obtained from ZVI. Transformer (bell or similar) with voltages up to 9 V, rectifying and with good filtration. It is very convenient to replace the existing audio amplifier IO TESLA MBA10DAS (with plate of condors) that its consumption, performance and dimensions (50 x 32 mm) was placed comfortably into space after the original amplifier and It listens to the speaker. May be supply voltage from 7.2 V to about 9 V 100 ma. EUB receiver has more space, a single segment switch, a simple potentiometer, so any transformers network resources, there may be comfortably placed. It should be noted that it must observe safety regulations on protection dangerous contact and terminal. According to oral and unsubstantiated reports were vacuum tubes replaced by transistors controlled field (namely plastic SM, SMY, except oscillators). Allegedly without change components. Both receivers incurred more than thirty flights are common and widespread before conception. Exceptions receiver R5, where he was receiving AI had solved unusual way. Where Both receivers okay then us today satisfy their parameters, size and weight. Regular maintenance is carried odborníkytechniky In time, usually at monthly deadlines in joining the workshop department. Belongs here cleaning contacts, terminals, jacks, plugs, switches and the like. Do not use aggressive media, such as e.g. petrol, benzene, trichloromethane, carbon tetrachloride, perchlorethylene,

16 dissolving plastic. Polluted Places to clean only athylalkoholem. Bearings and transfers easily mamažou silicone oil. From our perspective it is noteworthy mandatory regulation: after 300 hours operation had to be replace all the tubes, without taking account the hitherto faultless operation. When replacing the need to proceed very Carefully, flasks tubes are of poor glass. Guide when replacing the red dot the booth oval tubes with vyvedeného shielding. The same applies to semiconductors. About implemented Changes are kept records. The dossiers They are described in detail defects and their removal. Caring for batteries containing detailed directions, differing from other battery maintenance. Gas tight batteries are charged when closed Articles valves. Their opening and release matrices articles damages. Charges at 20 C. Accumulators, having behind 150 discharging and charging marches cycles must be replaced. Next detailed guidelines include charging currents and times, battery maintenance, etc. Literature: (1) Short instruction manual 5A and R5P (2) The RFT Empfängerrôhren 1957 (3) Kurzwellenempfänger EKB 1963 Rotaprint (4) Der Empfänger EUB Ministerium fur Nationale Verteidigung 1963 (5) Merkheft 62DTG "Institut fur Halbleitertechnik Teltow,, 1962 (6) Experience, reflection and conversations with amateurs from the DL. Picture caption: Fig. 8a) and 8b) Group diagram of a receiver EUB 1) The input filter without protective bulbs and neon lamps, 2) tuned input amplifier with RO1

17 DF669, 3) first mixer with RO2 DF669 4) MF-stage amplifier 10.7 MHz with RO4 DF669 5) second mixer with Ro5 DF669, the second controlled oscillator PCL / KRL / 7.6 MHz, 6) MF three-stage amplifier 3.1 MHz with RO 6, RÔ7 and RÔ8-3 x DF669, 7) auxiliary tuned oscillator with RO3 DF668, 8) Generator Sizing PCL / KRL / 3.1 MHz, 9) dvijitý MF transformer capacitively coupled with tubes RÔ8 10) AM FM detector - when AM is the anode voltage RÔ8 disconnected grid works as the anode of the diode. FM anode voltage is connected, Ro8 works as a limiter. The secondary winding of the second transformer MF works as an FM detector diode GR1 and GR2-2 x OAA 846, 11.12) transistor nf předzesiiovač without tone filter, and end with balanced amplifier output transformer TRS1 to Trs4-4 x OC811, 13) voltage converter - transvertor 7.2 V / 70 V and TRS5 Trs6 2 x OC821, Ba1) battery 1.2 V for heating tubes, Ba2) 7.2 V battery to power converters, and audio amplifiers. Note.: In the original scheme is accidentally drawn the connection between blocks 5 and 8.