SPECTRUM COMMUNICATIONS

Incorporating G2DYM Aerials & Garex Electronics

SW, VHF, & UHF Listener - 1 March 2017

Please email or phone for a quote or to place an order by credit/debit card or for a Paypal money request. Purchase of several items is likely to make a saving on postage. Tel 01305 262250

Orders & quote requests to  jean@spectrumcomms.co.uk

Technical queries to  tony@spectrumcomms.co.uk

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T4T Books I & II small.jpg Book 1 includes the first 27 articles of Technical for the Terrified, of which I am the author published in PW between February 2005 and August 2009 and have been compiled into a 124 page book of the same name. The writing style is aimed to be easy to read and should be of great value to readers of all technical levels.  Subjects include; a little maths, inductors & capacitors, DC circuits, transistor biasing, dB's, amplifiers, diodes & rectification, the superhet, SSB & CW, FM & AM, bandwidth, Q, antennas & feeders, band-pass circuits, RF/IF amplifiers, phase locked loops, HF transceivers, filtering in receivers, mixers, FET RF amplifiers.  Price is 12.00 plus 3.50 P&P.

Book 2 now available at 12 plus 3.50 P&P.  Buy both books and pay only a single 3.50 P&P.  Book 2 reproduces the next 23 articles from PW up to June 2013 and deals with components, equivalent circuits, crystal oscillators, amplifier stability, analogue low pass filters, transmitting ATU's, the superhet receiver, feeder cables and transmission lines, antenna gain and bandwidth, measuring RF power and SWR, measuring AC & DC voltage - inductance - capacitance - frequency & Q, circuit analysis, broadcast and television interference, singly balanced mixers, laying out PCB's, antenna advice for the listener, antenna tuning and the noise bridge, more on antennas and feeders, receiving 100kHz to 30MHz, homebrew receivers for the HF amateur bands, and circuit matching.   Just so much in it. 

PW Magazine is still available at some magazine sellers but often is hard to find amongst the many thousands of other magazines.  My series of Doing it by Design is published in Jan, Mar, May, July, Sept, & Nov.  Technical for the Terrified is published in Feb, Apr, June, Aug, Oct, & Dec each year.    http://www.pwpublishing.ltd.uk/

Contents

1W IC Audio Amplifier HF Tuneable Preamp RX Pi Aerial Tuning Unit
5 & 10 band RX front-end filtersG3RJV/G4CFY Regen RX Target AM/SSB Communications RX
Clara 2 Direct Conversion RX LS Audio Filter Top Band Receiver
Classic (2) RX board Multiband Synthesizer Triband Pesky Receiver
CW Audio Filter & AF Amp Pesky RX101 for PSK31 UK CB to 10 FM conversion
Dual Peak/Notch Filter Portland VFO VHF Masthead Preamps
Frequency Demodulator Receive Converters VHF Station Receive Preamps
HF 4 Band Converter RX L-type Aerial Tuning Unit VLF Converter

Spectrum Communication purchased Garex Electronics on 1 December 2011 from Peter Longhurst.  The purchase included the sole manufacturing and selling rights to the 2001, 4001, 6001, & 7003 range of FM transceivers, preamps, wire aerials, flexi-whip handheld aerials, rigid mono-band and dual-band mobile whip aerials and interference filters.  Many of the products have since been improved or completely re-designed.  

CLASSIC (2) RECEIVER BOARD. This is an SSB /CW receiver complete with the exception of local oscillator and front end band filter.  It uses push-pull FET mixer, a 6 pole crystal 9MHz (or 10.7MHz) IF filter, two MC1350P IF stages, an FET product detector, crystal carrier oscillators and a TBA 820M audio amplifier. It has 120dB AGC range and S meter output.  It can be used with a 5-5.5MHz VFO and switched front end filters for 80 and 20m operation.  PCB and data only 16.00 UK, 17.00 EU, 18.00 World. PCB & parts kit 64.00 UK, 70.75 EU, 71.75 World.  PCB built & tested 85.50 UK, 91.75 EU, 92.75 World.  Prices inclusive tracked carriage. 

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REGENERATIVE RECEIVER (G3RJV-G4CFY).  This is my development of the circuit described by George Dobbs G3RJV in April 2013 PW.  It comprises an FET infinite impedance detector and a conduction controlled Q multiplier or oscillator to enhance AM reception or receive and decode SSB signals.  It also includes an IC audio amplifier to drive a loudspeaker.   Version A 1.8-3.8MHz uses 45u0H coil.           Version B 3.5-7.5MHz uses 11u0L coil.             Version C 7.0-15.0MHz uses 2u6L coil.            Version D 11.0-23.0MHz uses 1u2L coil.               PCB & data 7.50 UK, 8.50 EU, 9.50 World. PCB kit 14.00 UK, 15.50 EU, 16.50 World. PCB kit and pots & polyvaricon 24.00 UK,  24.00 EU, 24.25 World.  PCB Built with pots & polyvaricon 32.50 UK, 36.00 EU, 36.50 World.  Prices include tracked carriage.

Knobs and phono socket NOT included.

 

VLF CONVERTER. Receives the band 5-500kHz and converts it up to 4.005 - 4.500MHz.   High input impedance to suit any random wire aerial.  500kHz elliptic low pass filter for input range, diode ring mixer, crystal oscillator, bandpass filter at IF centred on 4.25MHz.  Gain -2dB flat across the band. SO239 coax output to receiver .  Runs from a PP3 battery or external 12V bench supply. 

Box kit 53.50 UK, 59.50 EU, 62.00 World.  Box built 72.00 UK, 80.25 EU, 83.00 World. Prices include tracking.

 

MULTIBAND SYNTHESIZER. Designed to use as a 12 band local oscillator for a multiband HF receiver using a 5.0-5.5MHz tuneable IF. This board can also be used as a development and educational tool to explore the operation of phase locked loops.  For ease of use it is programmed by means of a diode matrix, not requiring knowledge of PIC or EPROM or Arduino programming and also keeping down power consumption.  The board as supplied has three voltage controlled oscillators tuning 7.0-9.3MHz, 12.0-16.5MHz, and 19.0-25.0MHz.  As supplied it is set for 100kHz frequency steps but can easily be modified for 50kHz, 25kHz, or 10kHz steps. It operates from a 13.5V bench supply drawing less than 50mA.  The output RF signal is a good sine-wave of amplitude 1.5V p-p.

PCB kit 57.50. PCB built and operational 85.50.

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 G4CFY 5 & 10 BAND FRONT-END FILTERS.  Triple bandpass coupled receive filters.  DC diode switched with 5 bands to a board.  Kit 5A 80/40/20,15, & 10m.  Kit 5B 160/60,30/17/& 12m.  Insertion loss below 5dB on all bands. Switching DC resistance 1k Ohms, draws 8mA from 8V or 12mA from 12V.  Two boards can be interconnected for 10-way band switching.  board size 92 x 84 x 15mm.  One PCB 5-band kit of parts 38.50 UK, 42.50 EU, 43.00 World. Single PCB built 53.00 UK, 57.00 EU, 57.50 World. Two PCB 10-band kit of parts, 64.50 UK, 71.50 EU, 72.50 World. Two PCB built 98.00 UK 104.50 EU, 105.50 World.

Prices include tracking.

TARGET HF3 AM/SSB COMMUNICATIONS RECEIVER  This is a masterpiece of RF engineering, covering 30kHz to 30MHz, which is includes the traditional Long Wave, Medium Wave, and Shortwave bands.  There is a large tuning knob coupled to a flywheel to give easy smooth tuning.  When turned slowly the frequency changes in 1kHz steps.  When turned faster it goes in 10kHz steps and when spun faster still goes in 100kHz steps.  There is a clarifier control to fine tune the receive frequency and of particular use when receiving single sideband stations.

The radio automatically selects a 6kHz bandwidth filter when the mode is used to select AM. It uses a 3.8kHz filter when the mode switch is used to select Upper Sideband or Lower Sideband.  The MEM button can be pressed to store a frequency and while in memory mode the main tuning dial can be used to view each of the stored frequencies.  There is also a recall button which return the frequency to the last one stored.

The receiver uses a first intermediate frequency of 45MHz and has a high side synthesized local oscillator providing exceptional stability.  A large clear liquid crystal display shows the receive frequency to a resolution of 1kHz.  The audio amplifier can produce up to 500mW rms audio drive to the large internal loudspeaker.  There is also an audio output phono connector sampling detected audio, prior to the volume control, that can be connected to the sound card of a computer.

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Various Features.  Sensitivity: AM 30kHz - 15MHz 2.5uV, 15MHz - 30MHz 4uV.  SSB 30kHz - 15MHz 1.5uV, 15MHz - 30MHz 2.5uV.  Phono antenna connector.  DC connector with 2.4mm pin.  Power requirement DC 12/13.5V at up to 300mA.  Dimensions 185x65x190mm.  Weight 1.3kg. Supplied with a random wire antenna, a DC power cable with in-line fuse, a BNC to phono adapter, and a DC 2.4 to 2.1mm adapter.  Please note, this is the only piece of equipment we sell that is not made by us.  Nevertheless I believe it is the best value for money receiver presently available to listeners.  In areas of high noise it can benefit from the use of an antenna tuning unit or an HF Tuneable Preamp.

Receiver 189.00.  Receiver & low noise PSU 12V 500mA 213.00.  Prices include tracking & insurance.    

 

HF TUNEABLE PREAMP,   2-32MHz in 4 bands.  With highly selective tuneable filters, reduces overload from strong broadcast stations.  Gain 10dB at band edges and 25dB mid band, adjustable down to 20dB.  12/13.5V DC operation at 20mA.  SO239 in/out connectors. Two-part stove enameled box 150x100x75mm.  Weight 410gms.  Box kit 58.50 UK, 68.00 EU, 72.00 World. Ready built 102.00 UK, 110.50 EU, 114.50 World, including tracking and insurance.

 

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HF 4 BAND CONVERTER. Converts the 3 WARC bands and the 60 metre band to the range 13.89-14.41MHz.  Suitable for use with older original amateur band receivers.  Bands A-C all read correct with the kHz in the range 14.068-14.409MHz and band D reads the kHz correct from 13.89-13.99MHz. Normally supplied with SO239 sockets for ANT and RX. Two-part stove enameled box 150x100x75mm. PCB kit 57.00, PCB built 79.00. Box kit 89.50, Ready built 141.00. Prices include tracked carriage.

 

RX L-type AERIAL TUNING UNIT   For short random wire end fed aerials.  Gives improved signal strength and lower receiver noise from 200kHz to at least 21MHz depending on wire length.  Diecast box 114x64x55mm. Fitted with terminals for aerial and earth inputs, and phono or BNC or SO239 coax output.  Includes a switch for tuner or bypass.  State required output connector when ordering.  Boxed kit 34.50 UK, 40.25 EU, 42.75 World.  Ready Built 43.25 UK, 49.25 EU, 51.75 World.  Including tracking & insurance.

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RX SPC AERIAL TUNING UNIT, for all types of antenna, except short random wires.  It has an SO239 socket for coax inputs and a binding post for direct random long and short wires.  It works from 1MHz to 32MHz and will tune high and low input impedances and provide a low impedance output via an SO239 socket to the receiver.  Housed in a two part stove enameled aluminium case 150x100x75.  Price 59.00 UK, 66.25 EU, 69.00 World.  Including tracking & insurance.

 

Clara 2 Direct Conversion Receiver.  Single band design, can be configured to work on 160m, or 80m, or 40m, or 30m, or 20m.  High stability Hartley VFO.  12/13.5V DC operation.  PCB kit 29.00 UK, 35.00 EU, 35.50 world.  Box kit 64.50 UK, 74.00 EU, 78.00 World. Box built 86.50 UK, 95.25 EU, 99.25 World. Includes tracking and insurance.

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PESKY RX101.  A single band 20m PSK receiver as a further development of the RSGB Centenary Receiver and the Sudden Receiver, with new bandpass coupled front-end filter and bipolar RF stage. The full historical development of this receiver from its 1st version in 1989 to the present day was the subject of Doing It By Design in PW in July 2014.  The receiver connects between the aerial and the computer and should prove an ideal companion for the Raspberry Pi computer.  Pesky RX101 PCB & parts kit 23.75 UK, 25.75 EU, 26.75 World. Box & hardware and PCB kit 34.75 UK, 38.75 EU, 39.25 World.  Ready built Receiver 48.75 UK, 53.25 EU, 54.25 World.

 

TRIBAND PESKY RECEIVER. A superhet receiver for the 80m, 40m, & 20m PSK31 frequencies.  DC switched front-end filters and crystal oscillators, 4-pole ceramic 455kHz filter, TCA440 main receiver IC and LM386 audio output IC.  Board size 117x81x15mm. Boxed unit 150x100x75mm.  PCB kit 58.75. PCB built with rotary switch and gain pot 85.00. Box kit complete 95.00. Ready built 134.50.

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QRP TX ATTENUATOR, RF SWITCHED. This allows a rig running 5W output to achieve QRP output levels of 500mW, 250mW, 100mW, and 50mW, using just three switches.  Straight through path when off.  

Box kit 49.50 UK, 55.50 EU, 60.00 World. Built 70.50 UK, 79.50 EU, 83.50 World. Including tracking and insurance.

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VHF PREAMP PCB, for inclusion into a receiver or transceiver.  It can be configured for any spot frequency in the range 40-200MHz.  Narrowband types have a typical gain in excess of 20dB.  Broadband versions have gain at the band edges of 9dB or more, and mid-band around 15dB. Supply 9-15V at 5-10mA. Size 42x19x14mm.  Stock frequencies 50-52, 70-71, 118-137, 137-138, 144-146, 156-162, 162-163MHz.  PCB built 14.50 UK, 15.50 EU, 16.50 World. 

VHF RECEIVE PREAMPS, Station type for 12/13.5V operation. These replace the Garex Preamps, which had provision for a PP3 battery.  Narrow band types with typically 25dB gain, Amateur 50-52MHz, 70-71MHz, 144-146MHz; Weather Satellite 137-138MHz; AIS 161-162MHz.  Wideband types with 9dB at band edge and up to 16dB mid-band, Airband 118-137MHz, Marine 156-162MHz.  HF-UHF 5-500MHz.  Two part stove enamelled box with choice of BNC, F, or SO239 connectors.  Supply requirement 12/13.5V at up to 10mA. Ready built UK 43.50, EU 48.00, World 49.00, including tracking and insurance.  

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VHF RECEIVE PREAMPS, Station type mains powered. Uses the same preamp board as the 12/13.5V station version with same frequency choices and gain. ABS box 101x77x41mm usually supplied with BNC sockets for ANT and RX.  Supplied with 1 metre mains cable with plug fitted. Ready Built 63.50 UK, 72.60 EU, 76.60 World. Prices include tracked carriage.

 

VHF RECEIVE PREAMPS MASTHEAD, with station box for internal 9V (PP3) or external 12/13.5V operation. Masthead unit in grey heavy duty waterproof ABS box 82x80x55mm with stove enamelled fixing plate and large releasable tie-wraps.  Preamp board the same as used in the station preamps with same choices of frequency and gain.  Station ABS box 75x56x25mm normally fitted with BNC connectors for ANT and RX.  Ready Built 58.50 UK, 67.25 EU, 71.25 World. Prices include tracked carriage.

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VHF RECEIVE PREAMP MASTHEAD, with mains powered station box.  Masthead unit in grey heavy duty waterproof ABS box 82x80x55mm with stove enameled fixing plate and large releasable tie-wraps.  Preamp board the same as used in the station preamps with same choices of frequency and gain. Station ABS box 101x77x41mm normally fitted with BNC connectors for ANT and RX.  Supplied with  1 metre mains cable with plug fitted.  Ready Built 87.75 UK, 96.75 EU, 100.75 World. Prices include tracked carriage.

 

DUAL PEAK/NOTCH FILTER with audio amplifier.  This unit plugs into an extension speaker socket of the HF receiver or transceiver and produces 500mW of audio to a front facing loudspeaker.  It can be used to notch out two unwanted heterodynes, or just one while enhancing the wanted audio frequency.  Similarly it can be used to sharpen otherwise dull audio or to dampen shrill audio.  PCB kit and all the hardware with drilled and labeled box 84.00 UK, 93.00 EU, 97.00 World, includes tracking.  Ready built 129.00 UK, 135.00 EU, 139.00 World.  Prices include tracking & insurance.

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CW or SPEECH PEAK FILTER, uses a Wien Bridge as a peak filter with high Q to provide a narrow audio passband centred on 700Hz for CW or on 1000Hz for speech.  Plugs into an extension speaker socket of a receiver or transceiver and provides up to 0.5W into an 8 Ohm speaker. PCB kit 16.00, PCB built 24.00.  Boxed unit in ABS box 123x83x59mm with loudspeaker and hardware in kit form 36.00, ready built 56.00.

LS AUDIO FILTER a unit to plug into the speaker socket of any communications receiver or transceiver uses active high pass and low pass filters to limit the audio range to within 300-2500Hz then re-amplify the audio and provide up to 0.5W into an 8 Ohm extension speaker.  PCB size 60x48x15mm.  Box size 110x60x31mm. PCB Kit 16.00, PCB built 24.00. Boxed unit in ABS box 123x83x59mm with loudspeaker and hardware in kit form 36.00, Ready built 56.00.

ACTIVE AUDIO BANDPASS FILTER.  This uses an active high pass and low pass filter to limit the audio range to within 300Hz to 3kHz for microphone or post demodulator filtering.  It is designed as an add-on board for existing equipment.  PCB kit 7.00.

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RECEIVE CONVERTERS add 2 or 4 or 6 metres to a receiver tuning 28-30MHz,  Types RC2-10, RC4-10, RC6-10 have 15dB gain a noise figure about 1.5dB. This design was put into production in November 2001 incorporating a diode ring mixer together with an improved oscillator and multiplier circuit. The Boxed version has panel adjustable gain, on/off switch and power LED. Fitted with SO239 connectors and has 1metre of lead for 13.5V bench power input. PCB size 95x45x17mm, Box size 102 x 84 x 40mm.  Types RC2-10, RC4-10, & RC6-10. PCB kit 36.00 UK, 40.00 EU, 40.50 World. PCB built 49.00 UK, 53.00 EU, 53.50 World.  PCB & hardware kit 63.25 UK, 71.50 EU, 74.25 World.  Ready built 86.00 UK, 93.75 EU, 96.50 World.  Prices include tracking & insurance.

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RECEIVE CONVERTERS add 4, 6 or 10 metres receive to a 2 metre transceiver. These are low noise using a mosfet RF & mixer stage and have 15dB gain. The Boxed version has panel adjustable gain, on/off switch and power LED. Fitted with SO239 connectors and has 1metre of lead for 13.5V bench power input. PCB size 89x45x17mm, Box size 102x84x40mm. Types RC4-2, RC6-2, RC10-2. PCB kit 36.00 UK, 40.00 EU, 40.50 World. PCB built 49.00 UK, 53.00 EU, 53.50 World.  PCB & hardware kit 63.25 UK, 71.50 EU, 74.25 World.  Ready built 86.00 UK, 93.75 EU, 96.50 World.  Prices include tracking & insurance.

PORTLAND VFO, a rock stable FET VFO for 6.995 - 7.205MHz for a direct conversion for the extended 40metre band, or 7.900 - 8.400MHz for use as part of a mixer VFO system as local oscillator on 70.000 - 70.500MHz band, or 5.0-5.5MHz for 20m and 80m rigs with a 9MHz IF.  Now includes upper band edge adjustment, and meets the requirement for the Intermediate License VFO project.  The Buffer (2A), mounted on the rear of the box, delivers 1.6V p-p into 50 Ohm with second harmonic 40dB down. Drilled Box and PCB kit with potentiometer and feedthroughs 35.00 UK, 39.50 EU, 40.00 World. Ready built 46.00 UK, 50.00 EU, 51.00 World. Prices include tracking.  State required frequency when ordering. 

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TOP BAND AM RECEIVER. Tuning 1.82 - 2.00MHz. The package includes a preselector PCB kit, a main board kit and a high stability boxed VFO. The main board has a receiver IC with S meter output, a 4 pole 455kHz IF filter, and a 500mW audio amplifier IC.  The VFO comprises an oscillator board, a buffer board, a 25pF C804 Jackson capacitor, and RFI screened VFO box.  Price for the complete kit package is 78.50, including tracked carriage.

1W IC AUDIO AMPLIFIER. A handy audio output stage using a TBA820M with a gain up to 48dB, 0.5W into a 8 Ohm load, low quiescent current, and low noise.  Article in PW March 2006.  PCB Kit 9.00.

SYNTHESIZER CONVERSION CB to 10FM This board is suitable for UK CB rigs with LC7136/7 or TC9119P PLL IC’s. Puts the rig onto 29.31-29.70 MHz. State rig type when ordering. PCB size 64 x 40 x 17mm. Type SC29. PCB Built & aligned 32.50, including P&P.

FREQUENCY DEMODULATOR & NOISE SQUELCH. This board adds FM detection and squelch to receivers such as FRG7, FRG7000, R600, & R1000 that use a 455KHz IF. Sensitivity 33uV for 3dB quieting. Produces 500mV AF output for fully quieting signal with + - 2.5KHz deviation. PCB size 69 x 49 x 17mm. Type FD455NS.  PCB kit 22.25, PCB Built 35.25, including P&P.

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