Incorporating G2DYM Aerials & Garex Electronics

Radio Amateur & Listener Products - 11 September 2015

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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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 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/


VLF Converter Classic (2) RX board G3RJV/G4CFY Regen RX
4001 FM 4m Transceiver VHF Transverters Top Band Receiver
Target AM/SSB Communications RX Dual Peak/Notch Filter 7MHz DSB Receiver
HF Tuneable Preamp CW Audio Filter & AF Amp 7MHz DSB 1/4W Transmitter
RX Pi Aerial Tuning Unit LS Audio Filter 5W Broadband HF Linear
RX Aerial Tuning Unit VHF Transmit Amplifiers Speech Processor
Clara 2 Direct Conversion RX Receive Converters 1W IC Audio Amplifier
PESKY RX101 for PSK31 Portland VFO PSK31 Interface
QRP TX Attenuator Mixer - Osc for 4 metres CTCSS module
VHF Station Receive Preamps 5 & 10 band RX front-end filters Toneburst Piptone & Kaytone
VHF Switched Station Preamps Poundbury SSB TX & RX IF UK CB to 10 FM conversion
VHF Masthead Preamps Poundbury 70MHz Front-end Frequency Demodulators

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 15.50 UK, 15.75 EU, 16.75 World. PCB & parts kit 61.25 UK, 66.50 EU, 67.50 World.  PCB built & tested 82.25 UK, 87.75 EU, 88.75 World.  Prices inclusive of P&P. 

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G3RJV-G4CFY REGENERATIVE RECEIVER.  This is a development of the circuit described by George Dobbs G3RJV in April 2013 PW.  It comprises an FET infinite impedance detector and a bipolar Colpitts oscillator with controlled conduction to act as a Q multiplier or as a carrier insertion oscillator. Version A 1.8-3.8MHz uses 45u0H coil.  Version B 5-10MHz uses 5u3L coil.  Version C 7-14.5MHz uses 2u6L coil.  Version D 11-22MHz uses 1u2L coil.   PCB & data 6.50 UK, 9.00 EU, 9.50 World. PCB kit 16.50 UK, 18.50 EU, 19.00 World. PCB kit and pots & polyvaricon 24.50 UK, 24.50 EU, 25.00 World.




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 51.00 UK, 57.50 EU, 60.00 World.  Box built 71.50 UK, 80.00 EU, 83.00 World. Prices include tracking.


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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, 44.00 EU, 45.00 World. Two PCB 10-band kit of parts, 65.50 UK, 73.50 EU, 75.50 World. Price include tracking.

4001 FM 4m TRANSCEIVER 70.2500 to 70.4875MHz in 20 channels in 12.5kHz steps. Really easy to use, not menu driven.  Default channel at switch-on 70.450MHz. Now upgraded to give excellent audio quality on receive and transmit.  RF output 5W or 25W presetable and switchable. Sensitivity better than 0.25uV for 20dB SINAD.  Audio output 500mW rms. Supply requirement 13.5V DC 4A on high TX, 1.5A on low TX, 130mA on RX.  This product is now being custom built to a high quality standard rather than down to the cheapest price. Now with improved performance type 4001S 195.00 UK , 203.00 EU, inc. tracking & insurance.   Type 4001SN with a really effective noise squelch to give a quite background and excellent weak signal reception 215.00 UK, 223.00 EU, inc. tracking & insurance.

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UPGRADE KITS FOR 2001, 4001, 6001

2001 PIC module to change to 12.5kHz channel spacing and add CTCSS. Supplied with replacement reference crystal, LED in-between channel indicator and handbook with new frequency listing. 22.50 excluding P&P.

4001 replacement PIC to change to 12.5kHz channel spacing. Supplied with replacement reference crystal and handbook with new frequency listing. 8.50 excluding P&P.

6001 PIC module to change to 10kHz channel spacing and add CTCSS. Supplied with handbook with new frequency listing. 20 excluding P&P.

Upgrade kit for 2m, 4m, and 6m versions for improved IF amplifier, better RX filter matching and improved transmit audio. Supplied with replacement IF filters 10M07 and LTW455HT and complete circuit diagram & board component layout 14 excluding P&P.

7003 upgrade to receive IF amplifier and transmit modulator section is pending post design work but is likely to be similar to the kit above except that the 21.4MHz first IF filter will not be changed.

Upgrade kit to add a Noise Squelch, NS1000F 20.00 excluding P&P.


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 215.00.  Receiver & low noise PSU 12V 500mA 237.00.  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 60.50 UK, 70.00 EU, 74.00 World. Ready built 103 UK, 112.50 EU, 116.50 World, including tracking and insurance.

RF SWITCHED version, 100W through power handling.  Fail safe operation, straight through path if unpowered.  Box kit 68.50 UK, 78.75 EU, 82.00 World.  Ready built 116.50 UK, 124.50 EU, 128.50 World, including tracking & insurance.

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RX Pi AERIAL TUNING UNIT, for all types of antenna.  It has an SO239 socket for coax inputs and a binding post for direct random long and short wires.  It works from 200kHz to 30MHz 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 63.50 UK, 71.50 EU, 74.50 World.  Including tracking & insurance.


RX AERIAL TUNING UNIT   For 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 32.50 UK, 38.50 EU, 41.25 World.  Ready Built 43 UK, 49.50 EU, 51.75 World.  Including tracking & insurance.

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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 28.00 UK, 33.50 EU, 34.50 world.  Box kit 64.00 UK, 72.00EU, 77.50 World. Box built 88.00 UK, 96.00 EU, 101.50 World. Includes tracking and insurance.


 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 23.50 UK, 24.75 EU, 25.75 World. Box & hardware and PCB kit 35.00 UK, 41.00 EU, 42.50 World.  Ready built Receiver 47.00 UK, 53.00 EU, 54.50 World. Pesky RX101.jpg


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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 48.00 UK, 56.25 EU, 60.25 World. Built 71.50 UK, 79.75 EU, 83.75 World. Including tracking and insurance.

VHF RECEIVE-ONLY PREAMPS, low noise and custom made for various frequencies.  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.  Boxed version, stove enameled with choice of BNC, F, or SO239 connectors.  Supply requirement 12/13.5V at up to 10mA. Boxed built UK 42.50, EU 48.25, World 49.75, including tracking and insurance.  

Old Design

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New Design

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VHF PREAMP PCB BUILT, 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 42 x 19 x 14mm.  Stock frequencies 50-52, 70-71, 118-137, 137-138, 144-146, 156-162, 162-163MHz.  PCB built 42x19x15mm 15.50 UK, 15.75 EU, 16.75 World. Tracking 5.50 extra.

STATION PREAMPS RF Switched, for 2 or 4 or 6 or 10 metres. 100W through rated on transmit. RF & DC switched 0-20dB panel adjustable gain. 2m, 4m, & 6m types use BF964 with noise figure under 1.5dB. 10m type uses BFR84, with noise figure under 3dB. Over-voltage and reverse voltage protected.   Protected against transients and EMP at input and output ports. PCB size 68 x 46 x 28mm. Purpose made box 76 x 70 x 38mm. Fitted with SO239 connectors. DC supply 13.5V 80mA. Types RP2S, RP4S, RP6S, & RP10S. PCB Kit 23.00 UK, 23.75 EU, 24.25 World. PCB & hardware kit 55.50 UK, 62.75 EU, 65.25 World. Ready built 77.00 UK, 85.00 EU, 88.00 World. Tracking & insurance included.

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MASTHEAD RECEIVE PREAMPS for 2 or 4 or 6 metres. 100W through rated on transmit. RF & DC switched and DC fed via the coax. Gain 20dB, NF less than 1.5dB. Supplied with a DC/RF Station Box with SO239 connectors for the shack. Heavy duty waterproof plastic box fitted with SO239 connector for feed coax and 1 metre of coax for connection to the antenna. Box size 82 x 80 x 50mm. Types RP2SM, RP4SM, & RP6SM. PCB & hardware kit 55.00 UK, 61.75 EU, 66.50 World.  Ready Built 81.50 UK, 88.25 EU, 91.00 World, including tracking.  Masthead fitting kit 8.00 extra.

MASTHEAD RECEIVE PREAMPS for 2 or 4 or 6 metres.  400W through rated on transmit. RF switched. Supplied via separate wire DC feed.   Gain 20dB, NF less than 1.5dB.  Protected against reverse and over voltage and against EMC transients at input and output. Heavy duty waterproof box fitted with SO239 connector for feed line and 1 metre of coax to connect to antenna feed point. Box size 82 x 80 x 50mm. Types RP2SH, RP4SH, & RP6SH.  PCB & hardware kit 48.50 UK, 55.00 EU, 58.00 World.  Ready built 70 UK 77.00 EU, 80.00 World, including tracking.  Masthead fitting kit 8.00 extra.

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TRANSVERTERS Early commercial transceivers often had a transverter facility with a low level output from the transmit driver stage and a means of disabling the power output stage.  This meant there were two connections for an outboard transverter, one from the low power transmit port, the other for receive via the main antenna socket.  Some of the top of the range rigs still have this facility but most modern rigs don't have any transverter facility at all.  To use them with a transverter simply reduce the power to minimum and use a single connection to the transverter from the rig antenna socket.  The RF sensing of the transverter will work at drive levels from 5W down to 100mW.  Below that drive level, hard switching is required.

Add 2 or 4 or 6 metres to a rig with 10 metres,  or 4 or 6 metres to a 2 metre rig.   The transverter main board contains an attenuator in the transmit path and can be configured for 1-500mW or 0.5-5W drive levels. Class AB linear operation gives all mode use.   The standard product includes a linear amplifier giving panel adjustable output 5 to 20W on 2m, or 5 to 25W on 4 or 6m.  All spurious and harmonic outputs better than 45dB below carrier.  Capable of withstanding long periods of transmit into bad SWR.  Receive side has panel adjustable gain 0-20dB gain and NF less than 1.5dB.   PCB size 150 x 93 x 18mm.     Box size 200 x 160 x 77mm. Suffix s is used for single IF drive arrangement, suffix d is used for dual IF drive version, the suffix L is for integral linear.

Types TRC2-10s, TRC4-10s, TRC6-10s, TRC6-2s, & TRC4-2s comprise just a transverter main board with 300mW output for use with a 10 metre or 2metre rig with 0.5-5W drive and single interconnecting lead.  Types TRC2-10d, TRC4-10d, TRC6-10d are for rigs with 10 metres with dual transverter TX & RX connections and drive in the range 1-100mW.   PCB Kit 67.50 UK, 73.75 EU, 75.50 World.  PCB built 96.00 UK, 102.25 EU, 103.75 World. Box kit 105 UK, 115.50 EU, 120.75 World. Ready Built 167.00 UK, 175.50 EU, 181.00 World. Prices including tracking & insurance. 

Transverters with two stage linear amplifier, 25W out for 4m or 6m version, 20W output for 2m version. Types TRC2-10sL, TRC4-10sL, TRC6-10sL, TRC4-2sL, TRC6-2sL are for use with a 10 metre or 2 metre rig with 0.5-5W drive and a single interconnecting lead.  Types TRC2-10dL, TRC4-10dL, TRC6-10dL are for rigs with 10 metres with dual transverter TX & RX connections and drive in the range 1-100mW.  PCB kits 167.00 UK, 173.50 EU, 176.50 World. PCB's built 207.50 UK, 214.00 EU, 217.00 World.  Box kit 209 UK, 218.50 EU, 225.50 World. Ready built 279.00 UK 288.50 EU, 295.50 World.  Prices include tracking & insurance.       

Transverters with repeater shift, types TRC2-10rs, TRC2-10rd, TRC2-10rsL, & TRC2-10rdL, add 8.50 to PCB kit or Box kit, 15 to PCB built or Boxed built.

ICOM COMPATIBLE TRANSVERTERS  A version of transverter specially dedicated to certain ICOM rigs, complete with 60cm long cables, ready to plug-and-play.  It is known to be suitable for the IC756Pro, 756Pro2, 756Pro3, 775, 781, 7600, & 7800, and any other rig not mentioned which requires just one TVTR IN/OUT RF lead plus a 7 pin DIN plug with a switching signal on pin 6.  Types TRC2-10L/IC1, TRC4-10L/IC1, & TRC6-10L/IC1.  Box kit 210.00 UK, 220.00 EU 227.50 World.  Ready built 281.00 UK, 290 EU, 297.50 World.

NOTE:  The following ICOM rigs are NOT plug and play compatible, but can be used with a standard transverter: 77, 78, 703, 706, 707, 718, 725, 726, 728, 729, 736, 737a, 738, 746, 746Pro, 756, 7000, 7400.


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 88.50 UK, 97/75 EU, 101.75 World, includes tracking.  Ready built 130.50 UK, 138.50 EU, 142.50 World.  Prices include tracking & insurance.

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CW FILTER & AUDIO AMPLIFIER, uses a Wien Bridge as a peak filter with high Q to provide a narrow audio passband centred on 700Hz.  Plugs into an extension speaker socket of a receiver or transceiver and provides up to 0.5W into an 8 Ohm speaker. PCB kit 16.50, PCB built 28.50.  Boxed unit with loudspeaker and hardware in kit form 37.00, ready built 54.00.

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 including LED and volume control 16.50, PCB built with pot 28.50, boxed kit 33, Ready built 50.50.  

ACTIVE AUDIO BANDPASS FILTER, uses active high pass and low filter filters to limit the audio range to within 300Hz to 3KHz for microphone or post demodulator filtering. Designed as an add-on board for existing equipment.  PCB Kit 7.00.

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TRANSMIT AMPLIFIER for use with Spectrum 0.5W Transverters. Two stage PTT switched class AB linear amplifiers for 2, or 4, or 6 metres giving a minimum of 20W out for the 2m version, and a maximum of 35W for the 6 metre version. Should not be run at more than 25W. Antenna relay with high speed TX/RX switching makes it suitable for all modes including data and RTTY and Packet. PCB size 125 x 57 x 28mm. Types TA2S4, TA4S4, TA6S4.   PCB kit 102.00 UK, 107.50 EU, 108.50 World.   PCB Built 112.50 UK, 117.50 EU, 118.50 World.  Prices include tracking.

TRANSMIT AMPLIFIER Single stage switched class AB linear amplifier suitable for CW, SSB, FM, RTTY, and PACKET. 4m and 6m versions 1W in gives 8W and 5W in gives 30W output. 2m version 1W drive gives 6W out and 5W drive gives 25W out. Switching circuit senses RF & DC and uses a monostable relay driver giving VERY FAST attack and a hold time of 250ms to 2s for SSB use. For data modes the hold function can be disabled. PCB size 102 x 72 x 25mm. Diecast box size 171 x 120 x 55mm. Fitted with SO239 connectors. Types TA2SA, TA4SA, & TA6SA. Ready built 103.50 UK, 111.50 EU, 115.50 World. Prices include tracking.

TRANSMIT AMPLIFIER Single stage switched class AB linear amplifier suitable for CW, SSB, FM, RTTY, and PACKET. 4m and 6m versions 5W in 30W out, 10W in 50W out.  2m version 10W in 35W out. Switching circuit senses RF & DC and uses a monostable relay driver giving VERY FAST attack and a hold time of 250ms to 2s for SSB use. For data modes the hold function can be disabled. PCB size 102 x 72 x 55mm. Diecast box size 171 x 120 x 55mm with a heatsink on top 152 x 99 x 32mm. Fitted with SO239 connectors. Types TA2SB, TA4SB, & TA6SB. Ready built 125.00 UK, 133.00 EU, 137.00 World.  Price include tracking.

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TRANSMIT AMPLIFIER (25W) & PREAMP.  Linear amplifier and receive preamplifier together in one case with independent switching. Amplifier details as TA-SA above, together with 20/26dB gain preamp. Types TA/RP2SA, TA/RP4SA, TA/RP6SA. Ready built 143.00 UK, 152.50 EU, 159.50 World.  Prices include tracking and insurance.

TRANSMIT AMPLIFIER (50W) & PREAMPLinear amplifier and receive preamplifier together in one case with independent switching. Amplifier details as TA-SB above, together with 20/26dB gain preamp. Types TA/RP2SB, TA/RP4SB, TA/RP6SB.  Ready built 174.00 UK, 183.50 EU, 190.50 World.  Prices include tracking and insurance.

TRANSMIT AMPLIFIER for 2, or 4, or 6metres. 250mW to 500mW input, 20w to 35W output, with RF & DC switching. Class AB operation gives clean output with intermod products 35dB down suitable for all modes CW, SSB, FM, & DATA. Designed as self contained amplifier as an add-on for 0.5W transverters such as MEON. Boxed size 127 x 102 x 38mm. Types TA2S2, TA4S2, & TA6S2. To be redesigned when time permits.

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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 95 x 45 x 17mm, Box size 102 x 84 x 40mm.  Types RC2-10, RC4-10, & RC6-10. PCB kit 30.50 UK, 36.00 EU, 37.25 World. PCB built 44.00 UK, 49.00 EU, 50.25 World.  PCB & hardware kit 61.75 UK, 67.75 EU, 71.75 world.  Ready built 85.50 UK, 92.00 EU, 93.50 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 89 x 45 x 17mm, Box size 102 x 84 x 40mm. Types RC4-2, RC6-2, RC10-2. PCB kit 30.50 UK, 36.00 EU, 37.25 World. PCB built 44.00 UK, 49.00 EU, 50.25 World.  PCB & hardware kit 61.75 UK, 67.75 EU, 71.75 World.  Ready built 85.50 UK, 92.00 EU, 93.50 World.  Prices include tracking & insurance.

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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 Licence 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 34.75 UK, 39.50 EU, 40.75 World. Ready built 52.50 UK, 57.25 EU, 58.50 World. Prices include tracking.  State required frequency when ordering. 

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MIXER - OSCILLATOR, a module for use in conjunction with the Portland VFO to produce a very stable local oscillator signal for a 4 metre receiver or transmitter with a 9MHz or 10.7MHz IF. Uses either a 51.4MHz crystal for a 10.7MHz IF, and a 53.1MHz crystal for a 9MHz IF. Comprises an overtone oscillator, a 4 quadrant multiplier mixer, a filter and buffer amplifier. PCB kit including choice of crystal 25.50 UK, 26.00 EU, 26.50 world. Ready built 34.00 UK, 34.50 EU, 35.00 world.

POUNDBURY (2) 9/10.7MHZ SSB Generator and Receive IF. A traditional SSB generator incorporating a speech processor.  Carrier suppression typically in excess of 50dB. The board now connects directly to an external SSB filter which has a termination impedance of around 560 ohms and a few picofarads. Other termination impedances can be accommodated by the change of a single resistor. The circuit has provision for USB and LSB carrier crystals which are DC switched. Receive section uses Fet and Mosfet IF amplifiers and a singly balanced diode product detector and discrete audio derived AGC. Includes 1W audio amplifier. The crystal filter and carrier crystals are not included in the PCB kit.  PCB Kit 69.75. PCB built 99.50.  Optional extras, SSB filter 18.00. Carrier Crystals 3.00 each. Mic gain 4K7 log pot, Volume 100K log pot, 1.75 each.  Signal meter 9.00.  8 ohm Loudspeaker 2.00.  P&P on optional extras 3.50.

POUNDBURY 70MHz FRONT END.  A receive preamp and mixer together with a transmit mixer and three amplifier stages to give 250mW output on 4 metres.  Works in conjunction with the Poundbury Generator & Receive IF, the Portland VFO, and the Mixer-VFO board to give a complete 4metre transceiver.  Can also work with the TA4S4 amplifier to give 25W output.  PCB & Parts kit including 2 panel pots 45.00.  PCB built 65.

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.

7MHz DSB RECEIVERA double sideband direct conversion receiver requiring just the addition of a Portland VFO local oscillator.  DiBD January 2007.   Can be used with the 7MHz DSB 250mW Transmitter using just the one Portland VFO.   PCB and kit of parts including volume control, 28.50 UK, 33.75 EU, 34.75 World.  PCB built plus 38.50 UK, 43.75 EU, 44.75 World. Including carriage.

7MHz DSB 250mW TRANSMITTER.  A double sideband transmitter comprising microphone amplifier, diode ring modulator driver and output stage. Works in conjunction with a Portland VFO and can be combined with the 7MHz DSB receiver to form a transceiver. The PCB kit of parts including a TO5 heatsink, a 10k log mic gain pot and wound toroids, price 29.00 UK, 34.25 EU, 35.25 World. PCB built plus log pot 38.50 UK, 44.25 EU, 45.25 World. Including carriage.

6-POLE CRYSTAL SSB FILTER. 6 crystal ladder filters for 9MHz and 10.7MHz. Bandwidth at -6dB 2300HZ .  Bandwidth at -60dB 6000Hz.  Shape factor 2.6:1. Insertion loss 2dB.  Termination 560 Ohms and less than 5pF.  PCB size 60 x 27 x 15mm.  Kit of parts 16.50 UK, 18.75 EU, 19.75 World.  PCB built 20.00 UK, 22.25 EU, 23.25 World. Including carriage.

5W BROADBAND HF LINEAR AMPLIFIER   Push-pull transistor HF linear covering the range 1.8-29.7MHz with full out for input levels between 37 and 97mW drive.  Harmonics typically are 2nd -42dB, 3rd -18dB, 4th -49dB and 5th -29dB.  This amplifier needs to be used together with a double Pi type low pass filter, details of which are supplied with the kit. Full kit of parts with drilled heatsink. Without wound toroids 34.50 UK, 42.00 EU, 44.50 World.  With pre-wound toroids 41.50 UK, 49.00 EU, 51.50 World.  Ready built and tested 49.50 UK, 57.00 EU, 59.50 World.  Tracking included.  Prices do NOT include the low pass filters.

SPEECH PROCESSOR to increase the sideband power and hence communications effectiveness of SSB and AM transmissions. The unit includes filtering which enhances the higher voice tones which carry most of the intelligibility. The peak to mean ratio of the transmission is improved by 10dB which has the same effect as increasing the transmit power by 10 times. It sounds nice too. Panel controls are included for clip level and output level. PCB size 82 x 45 x 17mm.    Type SP1000. Box kit 44.50 UK, 45 EU, 47 World. Ready Built 62.50 UK, 70.50 EU, 73 World.  EU & World prices include tracking.

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1W IC AUDIO AMPLIFIER, handy audio output stage 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.

PSK31 INTERFACE, designed as an interface between a computer sound card and a transceiver.  PCB kit 21.00 UK, 21.75 EU, 22.75 world.  Box kit with cables and jack plugs 37.00 UK, 44.25 EU, 46.75 World.  Ready built 50.00 UK, 56.50 EU, 59.00 World.  Includes tracking.

CTCSS Module.  Designed originally by Ken Ginn G8NDL, then modified and a new PCB layout by Spectrum.  Produces all nine CTCSS tones that can be selected by a link or using a 9 way rotary switch. The unit is triggered by the microphone PTT and in turn provides a PTT output to the rig via an opto-isolator. The module includes a trimpot to set the tone level output to accommodate different microphone impedances.  PCB size 67x55x10mm.  PCB kit 21.00 UK, 23.00 EU, 23.50 World.  PCB built & tested 27.00 UK, 29.50 EU, 30.00 World.  Including P&P.

AUTO TONEBURST stable RC oscillator to provide a 500mS burst of 1750Hz audio for repeater access. The board has option for 7-10V or 10-16V operation. PCB size 29 x 27 x 15mm. Type AT1750. PCB Kit 6.50 UK, 8.75 EU, 9.75 World. PCB Built 10.00 UK 12.25 EU, 13.25 World. Including carriage.

PIPTONE end of message tone for 250mS for weak signal SSB use. The unit provides 50mV across a 600 ohm microphone. The tone and amplitude are presetable. A relay is included for receive and PTT switching. PCB size 44 x 25 x 17mm. Type PT1000S. PCB Kit 9.50 UK & EU, 9.50 World. PCB Built 13 anywhere. Prices include carriage.

KAYTONE (a name coined by Spectrum) this unit is the successor to the original Kaytone sold in 1979. End of message Morse K particularly useful for weak signal or QRM situations. Adjustable pitch, speed, and level. A relay is included for receive and PTT switching. PCB size 58 x 39 x 15mm. Type KT1000. PCB Kit 14.00 UK, 14.50 EU, 15.25 World. PCB Built 21.00 UK, 21.50 EU, 22.25 World. Price include carriage.

SYNTHESIZER CONVERSION CB to 10FM 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 29.50 UK.       

FREQUENCY DEMODULATOR and noise squelch. 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 19.75 UK, 21.75 EU, 22.25 World. PCB Built 29.75 UK, 35.25 EU, 36.50 World. Prices include carriage.

FREQUENCY DEMODULATOR adds FM second conversion, amplification and detection to receivers with a first IF between 3 and 11MHz. Includes carrier level squelch with preset on the PCB. Sensitivity 2uV typical for 20dB S/N. Normal version has a 4 pole ceramic 455KHz 2nd IF filter but no first IF filter. 10.7MHz version available with 2 pole crystal filter at the input and 4 pole ceramic 455KHz 2nd IF filter.    Type FD3-11, PCB Kit 18.50, PCB Built 27.50. Type FD3-11F, PCB Kit 21.50, PCB Built 30.50.

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