Components List For The 7 Valve HF Superhet Receiver
Components list for the basic receiver
Resistors 0.5 watt except where stated
R3, R5, R7, R15. 47K.
R4, R12. 100K.
R6, R8, R13. 250K.
R9, R11. 330R.
R10. 470K. Please note this is incorrectly marked as R15 at the junction of C10 and pin 2 signal grid of V4 EBC 81 in the original circuit diagram. Please refer to it as R10.
R16. 47K or 22k when using a lower HT voltage of 100V.
R19. 6K8 1 Watt
R20. 150R 2watt minimum.
RV1. Volume Control 1M log potentiometer.
VC1/ VC2 365 PF Variable capacitor. Available from the following links. Jackson Brothers - Variable Capacitors and Drives or http://www.oselectronics.com
C1, C4, C5, C6, C7. 0.1uf Disc ceramic 500-1000V working voltage.
C2, C3, C10, C11, C15, C16. 0.01uf Disc ceramic 500-1000V working voltage.
C8. 240PF Silver mica or disc ceramic 350-1000V working voltage.
C9. 22uf 25V Electrolytic capacitor.
C12. 100PF Silver mica 350V working voltage.
C13. 1000PF Disc Ceramic 500-1000V working voltage. NB This value may need to be lower and may require a bit of experimentation with trial and error depending on the type of oscillator coil used.
C14. 10PF Silver mica 350V working voltage.
C17. 47uf 25V Electrolytic capacitor.
C18. 1uf 350-450V Electrolytic capacitor.
AF Transformer and speaker
T1- Valve type single ended output transformer with a Primary of 500K and secondary to suit 8 Ohm speaker. Available from the following links. SOWTER AUDIO TRANSFORMERS HOME PAGE or VVT Mains Transformers for Electronic Equipment
LS1 8 ohm 4 watt minimum. Choice of style is up to you.
IF Transformers and RF Coils
IFT 1, 2, 3. Toko YRCS11098 QTY 6. NB The type stated may not be available.
L1/L2 RF Mixer Coil. SW1 1.7 MHz to 5 MHz Toko KANK333R. SW2 5.5 MHz to 14 MHZ Toko KANK3334R.
SW3 12 MHz to 30 MHz Toko KANK3335R.
L3/4 Oscillator Coil. SW1 Toko KANK3426R. SW2 Toko KANK3337R. SW3 Toko KANK3428R.
Please note that these items are the original components I used in my version I built nearly 10 years ago and may not be easily available as the original ones I used. I will give you the following links to suppliers. BEC Distribution Ltd or Antique Electronic Supply where there modern transistor IF transformers would be suitable for the IF Stages.
Band Switch- 4 Pole 3 way if you intend to incorporate band switching or 6 Pole 3 way if you intend to use RF Amplifier stage. NB Due to the high risk of instability through inconvenient, It is recommended you use a separate switch or build it as a single band receiver when the RF stage is used.
Please refer to the following link How To Get Components which has a list of valve suppliers and links to other sites regarding the component availability for this receiver.
Components list for the BFO Beat frequency oscillator. Note, Only needed for the reception of SSB Single sideband or CW Continues Wave
Resistors 0.5 Watt
R1, R2, R3,- 47K
C1. 100PF Silver mica 350V working voltage
C2. 0.1uf Disc ceramic 500-1000V working voltage
C3 10PF Silver mica 350V working voltage.
VC1 10-15PF Variable capacitor.
L1 455 KHz Toko YRCS11098.
S1 Single pole toggle. NB Must be high voltage insulated type and at least capable of switching a minimum of 250 Volts.
Components list for optional RF Amplifier Stage
Resistors 0.5 Watt
RV1. 1M Lin. High power potentiometer 2 Watt 350V minimum working voltage.
C1, C2. 0.001uf Disc ceramic 500-1000V working voltage.
C3, C5. 0.01uf Disc ceramic 500-1000V working voltage.
C4. 0.1uf Disc ceramic 500-1000V working voltage.
C6. 100PF Silver mica 350V working voltage.
VC1 350PF Variable capacitor.
L1/2 are the same range as the L1/L2 mixer coil. Alternatively you can omit VC1 and use a wide band choke of 4.7mh, Like the circuit I use for my TRF Receiver.
Isolating capacitors, When using transistor type IF transformers
C1/2. 100PF 500-100V Disc ceramic. You will need a total quantity of 6. Please note that these are not required when using valve type IF transformers.
Components list for the HT Power supply
RX safety bleed resistor. 470K 2 Watt.
T1 Mains transformer. Primary 230 Volt AC for UK mains. Secondary 1 X 6.3V AC 1 amps centre tapped for EL84. 1 X 6.3V AC 2 amps centre tapped for receiver valves. HT 70V AC at 100 milliamps for a RMS of 100V DC or 100V AC at 100 milliamps for a RMS of 150V for high voltage version. Available from the following links SOWTER AUDIO TRANSFORMERS HOME PAGE or VVT Mains Transformers for Electronic Equipment
CH1 Smoothing choke. 10 Henries rated at 100 milliamps. Available from the above suppliers.
C1/C2 100uf 350-450V Electrolytic capacitor.
D1-4. IN4009 or 1 amp bridge rectifier at 400V minimum rating.
S1A/S2B. 2 Amp mains rated double pole toggle switch.
F1/F2 100 milliamp Slow Blow fuse.
Valve holders B9A chassis mounting type. You will need a total of 5 for a basic working receiver and a total of 6 for the complete 7 Valve receiver when using the BFO. You also need a B7A Chassis mounting type valve holder for the RF stage.
Veroboard. Plain matrix for mounting power supply components and IF and RF Transformer. NB Do not even think of using stripboard as it is subject to high voltage tracking due to the close proximity of the copper tracks.
Vero pins for connecting wires on boards.
Tagboard for the interconnection of HT points and heaters.
Connecting wire for valve heaters. twisted insulated bell wire 6 amp minimum, preferably black.
Connecting wire for HT. Red and black insulated stranded at about 1amp. Must be at least mains rated at 350V. Not low voltage bell wire.
Chassis available from Maplin > Electronic Components. Code KR57M.
Please refer to the following link How To Get Components for complete list of suppliers of the components for this receiver. You will in addition need nuts, bolt, spacers, other things such as mains cable and a plug fused at 3 amps.
Back To-Severn Valve HF Superhet Receiver Designed For Advanced Constructors