Franzis_-_The_valve_radio_kit_user.pdf
The Valve Radio Kit The complete kit with valve, case and all the other needed parts Hear radio stations as in the pre-transistor days of 50 years or more ago This nostalgic looking radio is a relatively simple straight-through valve shortwave receiver using manual feedback. The principle by which the receiver works is similar to the Audion valve system from the dawn of radio reception history (See http:/en.wikipedia.org/wiki/Audion_tube) originally patented by Lee De Forest in 1906. 80 years ago the Audion design could be found in many homes, also it could be found in many amateur rigs, military equipment and telecommunication units, as well as many ship to shore“ radio units. An Audion (See: http:/en.wikipedia.org/wiki/Audion) is a simple type of radio receiver where no mixing is required of intermediate frequencies (as in superhet radio) (http:/en.wikipedia.org/wiki/Regenerative_circuit) is required to help improve reception and selectivity. The adjustable feedback as used here is the main reason for the good to excellent receiving qualities of this Audion style radio. Through fine adjustment of the amount of feedback it is possible to change both the amount of amplification (volume) and the selectivity of the radio and it can therefore be finely and correctly tuned for each and every station received, e.g. you can achieve the optimum/best signal quality possible. Because of this, the receiver is not quite so simple to operate as many later superhet designs are, but it can achieve from a far more simple (and cheaper!) design, a similar performance to most modern good quality world“ receivers, and in some cases to actually beat them (no pun intended!) at their own game! Please take plenty of time to make sure that you fully understand all the details of short wave receiving with this radio, you can start with it to enjoy the world of glowing electronic valves (tubes) and their special audio tone that they give to received stations. You will be able to hear the transmitters of many foreign countries, especially in the evenings and after careful & fine adjustment of the Tuning frequency and the feedback pot, it will allow many even more distant stations to be clearly heard. The valve used here is a 6J1 which was for many years only seen in military telecommunication equipment. It is a special high frequency valve, with particularly low cathode heating power requirement. The radio functions using both a low tension“ heater 6 volt battery and a high tension“ battery of just 9 volts, with an actual anode voltage of around 15 volts. The 6J1 is basically the same as the European EF95 valve, that was also extensively used in both commercial and military telecommunication equipment, but never in radio or TV equipment intended for domestic usage. Only since valves have been mainly replaced by semiconductors has it been possible to actually get hold of such units from the Days of Glory“ of glass valves for personal experimental usage. You can find out more about this on the internet under:http:/www.elo-web.de/elo/radio-r-hrentechnik/franzis-r-hrenradio but only provided you are able to read the German language! The internet based ELO Magazine of the Franzis publishing house is full of projects, tips and information with regard to electronics, both valve and semiconductor based. This online magazine also has a particular page supporting this valve radio for users. This may prove useful for when you run into problems or you want to try some further development with this valve radio. But as I have mentioned before, the information on their homepage is ONLY in the German language. Page 1 Fig.1. Components. Component list 1x valve 6J1 + socket/holder 1x T1 NPN transistor BC547 1x printed circuit board 1x T2 NPN transistor BC547 1x variable capacitor 265pF 2x R1, R4 100 k (brown, black, yellow) 1x short-wave coil on an adjustable ferrite core 2x R2, R3 1 k (brown, black, red) 1x L1 loudspeaker 8 ohm, 0.5 W 1x R5 470 k (yellow, violet, yellow) 1x P1 feedback pot 22K 2x R6, R7 10 k (brown, black, orange) 1x P2 volume control pot 22K log with switch 1x C1 10 pF ceramic (10) 4x 4 mm banana sockets. 1x C2 100 pF ceramic (101) 2x 4 mm banana plugs 1x C3 10 nF ceramic (103) 2x 1 meter Insulated connecting wire, flexible 1x C4 100 nF ceramic (104) 1x B1 battery holder for 4 x AA cells 1x C5 electrolytic 10 F axle extension for the tuning capacitor, case 1x C6 100 nF ceramic (104) assorted control knobs for the various controls 3x C7, C8, C9 electrolytic 100 F Mounting the components The variable tuning capacitor is used to set up the required receiving frequency. Place the axle extension on the variable capacitors axle and fix it securely using the 2.5 mm grub-screw provided. See the middle and RH pictures below. Make sure that while screwing the grub-screw down tight, that you do not run into one of the capacitor end stops and accidentally damage it. Before fixing the screw, ONLY hold the axle firmly with pliers or grips, but without causing any damage. The variable capacitor will be later held securely in the case with two small screws (supplied). Fig.2. The variable capacitor (3 views) Mount the loudspeaker in the case by pushing it gently into the slits provided. The solder connections should be orientated towards the bottom of the case, so shortening the required connections to the PCB, which they also support a little. The loudspeaker should sit firmly in the slits provided, but a small drop of (hot!) glue or similar can be used to make certain of this. See photo of the fitted loudspeaker below. Page 2 Fig.3. Loudspeaker The volume control (22k P2 log) with its three connections, also contains an integrated on/off switch. When turning the volume control from right to left (anticlockwise), the switch will be opened (off). Place the volume control pot in the left-hand case hole (viewing from fron of case). A small tongue on the pot stops the body from turning while in use. The tongue is shown in all of the next 3 pictures, in the middle one its in the hole mentioned. Secure the pot with the ring nut supplied, do not forget to install the special washer while doing this to stop it turning when in use. Install the feedback pot (22k P1) in the same manner as the volume control, but in the middle case hole. Fig.4. Volume control with on/off switch P2 (pot) Anti-twist tongue in hole Feedback control P1 (pot) Fig.5. Aerial sockets and plugs ount the four sockets in the case. MThe socket next to the case edge should be the red earth connection, the other three should be the nside the case. three brown aerial connections. Orientate the solder tags as shown in the photo below. Fig.6. Positioning of the various elements in the case. Shown from i Page 3 Soldering To complete the radio, 13 insulated stranded wire connections are required. Cut them to the following lengths: 2 x 4 cm / 3 x 6 cm / 4 x 8 cm / 4 x 9 cm. Remove the insulation at each end for about 5 mm. The plastic insulation is very soft and can usually be removed using your fingernails. If using cutters, try not to damage the strands. A proper stripping tool is best. Twist the strands together and tin the ends carefully to stop them splaying out when soldering. Hold the hot tip of the soldering iron and the solder together on the cable ends. The solder must completely fill the end of each wire. wires of soldering techniques, use the tinning of the wire ends as a way to become more miliar with the method. For those who can read German, there is a short tutorial on soldering at www.elo-web.de in German. ty questions, but the PCB is very clearly marked. Do not solder in anything till you are 100% sure how & where! tioning on the PCB. nly electrolytic caps are polarised (that means that they must be correctly orientated), the other caps here are not polarised and can be e PCB at all times. The valve base, for example, is mounted on the opposite side to all the other components. Check ! Do please use those infos to identify each R3, 1K (brown, black, red), R4, 100K (brown, black, rown, black, orange). ding form, to make sure that you t behind to hold it in the PCB. till soldered older both of the wires on the bottom of the PCB and cut any extra off with sharp side cutters leaving approximately 2 mm protruding. arning: do not cut off the wires too short as this could eventually mechanically damage the PCB lands. Fig.7. Finished In the case where you have little or no experience fa Here is one in English: Now you can start soldering the components onto the supplied PCB, the schematic on the last page will help with regards to orientation of each component if you have polari Fig.8. Component posi Resistors have usually 4 bands of colour, one usually being silver or gold, start reading the colours from the non silver or gold end only to get the correct value. See resistor colour code chart on the last page before the schematic. O placed either way round in the PCB. Place all the components in/on the PCB, feeding the wires through the correct holes. Make sure that you put the components on the correct side of th the photos carefully! (Details in the brackets are to help identify THAT particular component component before starting) Start with the resistors R1, 100K (brown, black, yellow), R2, 1K (brown, black, red), yellow), R5, 470K (yellow, violet, yellow), R6, 10K (brown, black, orange), R7, 10K (b Bend the connecting wires to fit them in the relevant PCB holes. Use fine nosed pliers or a resistor ben do not bend a resistor wire next to the component body, or it might break off. Bend neatly! Mount carefully, do not strain the component body. Splay the wires ou S W Page 4 Fig.9. Mounting the resistors Now fit the ceramic capacitors in place: C1, 10 pF (10), C2, 100 pF (101), C3, 10 nF(103), C4, 100 nF (104), and C6, 100 nF (104). ig.10. Fit IC1, T1 and the capacitors Place the four electrolytics 10 F (C5) and the 100 F (C7, C8, C9). Make sure that these are correctly orientated with the + and - in the correctly marked holes. DOUBLE CHECK, ITS VERY IMPORTANT! On the capacitors, the plus pole is next to the longer wire and the minus pole has an extra white minus sign marking on the plastic insulation. As a check, C8 has the minus pole downwards, the other three. has it pointing upwards. Now you need to insert the semiconductors in the correct positions. Note that the BC547 transistors (T1, T2) have a flat on the side of the plastic case for orientation purposes. Make sure that this lines up with the similar markings on the PCB. The audio amp LM386 chip has a small indentation by pin 1, this is also shown on the component plan on the PCB, Orientate the chip in the same way so that pin 1 on the LM386 is near to connector P4. See next photo. e way due to it having three connections on one r components. See here:- F Fig.11. Electrolytic capacitor placement Fig.12. Placing of the transistors Now orientate and fit the coil (L1) and the valve socket. luckily the coil can only fit on side and two on the other. The valve base must be mounted on the opposite side of the PCB to the othe Page 5 Fig.13. Solder in the coil and valve base Place the valve in the base and check that the valve and base toge gently bent to fit properly to make sure that pr ther fit correctly in the PCB. Sometimes the base pins need to be oper contact is made. Do make sure that the valve is sitting vertically while doing this. w he first actual fixing for the PCB is the variable capacitor wire connections to the PCB, so do not forget to orientate it correctly. 4. The ed in practise though. The middle connections are also connected to the axle of the variable capacitor and make together the earth connection for it. Also there is an extra trim capacitor that lies above C1 and C2. It has its own connections. Solder the wires first onto the PCB before soldering to the tuning capacitor. acitor Once that has been done, place the outer ing each step carefully. Then carefully solder better in its position. The doubled connections have two jobs, one is the correct functionality of the variable capacitor, the other is they add needed extra stiffness to the PCB fixing. See photo above. Also, the connections to the loudspeaker serve in a similar manner, adding further mechanical stiffness to the PCBs position. Recheck. Push the PCB and the valve on its base into the final position, checking carefully that the valve sits exactly behind the windo in the case front and inside the cover. T Fig.14. Solder the variable capacitor connections next, it has several, on the case of the variable capacitor are markings of C1, C2, C3, C segments C1 and C2 have each 265pF. Only C2 will actually be us Fig.15. Connecting the PCB and variable cap As previously mentioned, the variable capacitor is also the mechanical fixing for the PCB via its connecting wires. These must be carefully adjusted for position and length before soldering. Solder only the middle variable capacitor connection first in lace, then carefully adjust the position of the PCB to get it both flat and horizontal. p connections carefully in place and solder them to the variable capacitor, one by one. Check e shorter connections C1 and C2 to the longer connections. That way you hold the PCB mechanicallyth Page 6 Fig.16. Fitting of the PCB. Next, solder the rest of the precut wires onto the PCB. They can easily be pushed through the relevant holes in the PCB and soldered securely on both sides. he connection marked Bat -6 V“ must be soldered to the black wire (-) of the 4 x AA battery Holder. The red wire (+) must bT a e carefully nd quickly soldered to one side of the volume control switch contacts, to prevent melting of the plastic switch. peaker can be replaced with solid insulated wire to further improve the mechanical upport of the PCB, if it is felt that extra strength/stability is required. Fig.18. The finished wiring Using the plan of the PCB, connect the aerial sockets to the PCB, the loudspeaker, the feedback pot P1 and the volume control pot P2 and the PP3 battery clip, observing polarity carefully - red to positive (Bat +9V). Now you have completed the main part of the building of this shortwave radio. nd build date and either photocopy or cut out the ill still be in a position to understand and possibly repair the radio ever needed at any time in the future. is is the way it was done in the days of valve radios, no searching for the schematic, its always right where you need it! et the earth and aerial cables ready for usage. From the rest of the stranded insulated wire you should still have around 1 meter left. Cut this into two approximately similar lengths and remove the insulation from each end and attach a single 4 mm plug to each wire. The earth cable should have several centimetres of insulation removed as this
