Stocks of the coil equivalent to TOKO 3335R are now in stock. Other 10mm coils are in the process of procurement to establish a new range of coils made specially for Spectrum.  These will include the following values, 0.4uH, 1.2uH, 2.6uH 5.2uH, 11uH, 23uH, & 45uh.  Taps will be provided to suit aerial input and Hartley oscillator use.  Eventually it is hoped to include duplicates in each value with taps to suit interstage use.

Problems with the supply of driver and output stage power RF devices for Spectrum Transverter caused a delay in the supply of kits and ready built units.   These have been overcome with stocks suitable for the next 6 months of driver devices. Thereafter it may be necessary to re-lay the power amplifier board to accommodate a flange mount device.  It seems there is only one company in the World producing 0.5W input and 5W output devices in a stud mount package, and 1 in 4 is faulty when tested at Spectrum.  Nevertheless there is a suitable flange mount alternative still in production and I will produce a new board to accommodate it before stock of the stud mount device are exhausted.

The new high power rated twin feeder is meeting the approval of all who have had samples and who have purchased it.  This feeder supplied with G4CFY trapped dipoles is performing well and receiveing acclamation.  Those who have purchased it for for their own dipoles are really impressed with its construction and performance.

Update 26 April 2009

New low impedance twin feeder, now in stock.  24/0.2 cores individually polyethylene sleeved with an overall sheath of polyethylene. 2kW rated with an SWR less than 2:1.  Loss only 0.04dB/m at 10MHz.  75p/metre plus carriage at cost, or £70 for 100 metre drum including P&P.

Supplies of TOKO coils are now drying up, with the exception of one company with stock at high prices.  TOKO stopped production of the 10K and 10E series over a year ago.  I have now found a company in the far east able to manufacture equivalent parts and initial supplies of the popular 3335R type is now on order.

Update 6 January 2009

PSK31 computer interface kit, as featured in February 2009 issue PW, now taking orders.  PCB on its own £5 inc P&P.  PCB and components £21 inc P&P.  Complete kit with box and hardware, cables and jack plugs £35.50.

Update 18 November 2008

A week later than planned our prices have been re-worked.   Many prices have gone up, some have stayed the same and surprisingly some have gone down.  All orders received from the time the web-site is updated will be at the new prices.

Update 26 October 2008

Spectrum Communications now has a new business bank account so that Credit Cards can be accepted.  The card terminal should be in operation from 29th October.  Our prices remain the same for many years and then circumstances force a rethink.  We are now re-calculating prices of all kits and ready built items to include in particular increased postage charges. 

         Contents

LCR Bridge     NEW PRODUCT

Off-Air Frequency Standard    

Two Tone Tester

Top Band Receiver   

Station Receive Preamps, 2m, 4m, 6m, & 2m.

Masthead Receive Preamps, 2m, 4m, & 6m.  Masthead fitting kit available for both types.

Transverters (or Transceive Converters), for 2m, 4m, & 6m.

Transmit Amplifiers for 2m, 4m, & 6m, 1W to 50W.

Mellstock 2 channel 1W AM 4 metre Transmitter

Mellstock 2 channel AM 4 metre Receiver

Receive Converters, 10m through to 2m.

Portland VFO for 40m or 4m

Mixer - Osc for 4 metres

Poundbury SSB Generator & Receive IF  

Poundbury 70MHz Front end mixers and amplifiers  

Speech Processor

LS Audio Filter

Frequency Demodulators.

Repeater 1750Hz toneburst.

Piptone, end of Transmission bleep.

Kaytone, end of Transmission bleep.

UK CB to 10 FM conversions

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LCR BRIDGE  with 5 resistance ranges, 100, 1K 10K 100K, & 1M.  3 capacitance ranges, 100pF, 1nF, 10nF, and 3 inductance ranges 1mH, 10mH, & 100mH, plus an external reference.  Scale calibrated 0.01 to 10 times reference value.  Optional drilled and labelled plastic or diecast box.  PCB & Parts with pot and switch £26.00.  With plastic box £39.00, with diecast box £44.00.

OFF-AIR FREQUENCY STANDARD This is a crystal calibration unit phase locked to Radio 4 on 198kHz using a two-loop system.  It includes a monitor receiver to ensure Radio 4 is being heard loud and clear.  Fixed outputs are 10MHz at 2V p-p, and 1kHz at 1V p-p as an oscilloscope CAL signal.  Switched outputs are 1MHz, 100kHz, 10kHz, and 1kHz at 6V p-p into 500 ohms.  Single board design as featured in July & September 2008 PW.   Background heterodyne whistle at 2kHz confirms lock condition.  12/13.5V DC operation at 65mA.  PCB kit with ferrite rod aerial £50.00.  PCB kit plus drilled box and hardware complete £86.00.  Ready Built £131.50.

TWO TONE TESTER, a useful test unit for power output, envelope, and carrier suppression testing of AM, DSB, and SSB transmitters. PW Feb 2005. Either 1600Hz or 1800Hz tones or both. Diecast box size 102 x 84 x 40mm. PCB £9.75. Box kit with all hardware £28.00.  Ready built £52.50.

TOP BAND AM RECEIVER. Tuning 1.82 - 2.00MHz. Comprising a main board with receiver IC, 1W audio amplifier, a 4 pole IF filter, and S meter output.  Also a high stability VFO with oscillator board, buffer board and RFI screened VFO box.  Also a tunable preselector with diode switching for use together with a transmit strip. All three boards, all the components, and drilled VFO box, and 25pF C804 Jackson capacitor, total price £78.50.

STATION RECEIVE PREAMPS 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 £20.00, PCB Built £30.00, PCB & hardware kit £35.00, Boxed Built £57.00.

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 to 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 £41.00, Ready Built £65.00.  Masthead fitting kit £6.00.

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 £42.50,  Ready built £65.00.  Masthead fitting kit £6.00.

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TRANSCEIVE CONVERTERS   Early commercial transceivers often had a transverter facility with low level output from the early transmit stages and a means of disabling the power amplifier stage.  This meant there were two connections for an outboard transverter, one from the low drive transmit port and the other for receive using the main antenna socket.  Some top of the range rigs still have this feature but most modern rigs don't have any transverter facility.   To use them you simply reduce the power output from the rig to as low as possible and use a single connection to the transverter from the antenna socket.  The RF sensing in the transverter then looks after RX/TX  switching.

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 0.5-10W 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 206 x 160 x 77mm. Types TRC2-10, TRC4-10, TRC6-10, TRC6-2, TRC4-2. 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.

Transverters giving 0.5W output for use with 10 metre or 2metre rig with a single connection and 0.5-10W drive. TRC2-10s, TRC4-10s, TRC6-10s, TRC4-2s, TRC6-2s.    Also Transverters giving 0.5 W output for use with a 10 metre rig with dual transverter connection and 1mW-500mW drive. TRC2-10d, TRC4-10d, TRC6-10d.                                                      UK prices by any method, PCB Kit £60.00, PCB built £92.50, Box kit £101.00, Boxed built £148.00.                     Rest of Europe by any method, PCB kit £62.50, PCB built £95.00, Box kit £106.00, Box built £153.00.                   

Transverters giving 25W output for use with 10 metre or 2 metre rig with single connection and 0.5-10W drive, TRC2-10sL, TRC4-10sL, TRC6-10sL, TRC4-2sL, TRC6-2sL.   Also Transverters giving 25W output for use with a 10 metre rig with dual transverter connection and 1mW-500mW drive, TRC2-10dL, TRC4-10dL, TRC6-10dL.                                        UK prices by any method, PCB kit £141.00, PCB built £187.00, Box kit £179.00, Boxed built £266.00.                 Rest of Europe by any method, PCB kit £144.50, PCB built £190.00, Box kit £184.00, Boxed built £271.00.       

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.

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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. 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 £81.00, PCB Built £94.00.

TRANSMIT AMPLIFIER Single stage switched class AB linear amplifier suitable for CW, SSB, FM, RTTY, and PACKET. Versions for drive levels of 1W-5W and output levels of 8W-30W. 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 71 x 17mm. Diecast box size 127 x 102 x 38mm. Fitted with SO239 connectors. Types TA2SA, TA4SA, & TA6SA. PCB Kit £54.00, PCB built £65.00, PCB & hardware Kit £63.00, Ready Built £82.00.

TRANSMIT AMPLIFIER Single stage switched class AB linear amplifier suitable for CW, SSB, FM, RTTY, and PACKET. Versions for drive levels of 5W-20W and output levels of 22W-60W. 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 71 x 17mm. 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. PCB & hardware Kit £70.00, Ready Built £89.00.

TRANSMIT AMPLIFIER & PREAMP.  The amplifiers described above and a matching preamp from the RP2S series together in one box with independent switching. 1W-5W in 8W-30W out, together with 20/26dB gain preamp. Types TA/RP2SA, TA/RP4SA, TA/RP6SA. PCB & hardware Kit £89.00. Ready Built £123.00.

TRANSMIT AMPLIFIER & PREAMP.  The amplifiers described above and a matching preamp from the RP2S series together in one box with independent switching. 5W-20W in 22W-60W out, together with 20/26dB gain preamp. Types TA/RP2SB, TA/RP4SB, TA/RP6SB.  PCB & hardware Kit £92.00. Ready Built £126.00.

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. PCB & hardware kit £109, Ready built £130.00.

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MELLSTOCK 1W AM 4 metre TX, a two channel transmitter with integral speech processor. PW Sept & Oct 2005. PCB £16.00. Mod Transformer £9.50. Crystals £8 the pair. PCB & component kit with crystals & transformer but without hardware £57.50. 

MELLSTOCK 4 metre AM RX, a two channel receiver as a companion for the Mellstock TX. PW Nov 2005. PCB £10.00. Crystals £8 the pair. 100uA edgewise S meter £9.00.  Complete PCB kit, volume control,channel toggle switch, crystals, and meter £57.00.

RECEIVE CONVERTERS add 2 or 4 or 6 metres to a receiver tuning 28-30MHz,  Types RC2-10, RC4-10, RC6-10 are low noise and have 15dB gain. This is a brand new design productionised 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 £29.00, PCB built £42.50, PCB & hardware kit £44.00, Ready built £69.50.

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 Types RC4-2, RC6-2, RC10-2. PCB Kit £27.50, PCB Built £40.50, PCB & hardware kit £42.00, Boxed Built £67.50.

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PORTLAND VFO, a rock stable FET VFO for 6.985 - 7.215MHz 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.  PW project March 2006.  Supplied with Buffer 1 for low level mixers or Buffer 2 for high level drive mixers. PCB and component kit with potentiometer £16.00. Drilled Box and PCB kit with potentiometer and feedthroughs £25.00.  Ready built units £49.00. State required frequency when ordering.  Version for 5.0-5.5MHz PCB kit £17.00, Boxed kit £26.00.

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 £25.00. Ready built £35.00.

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 500 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 and component kit £60.00.  Optional extras, 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 £2.50.

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.  Front End Board PCB & Parts including 2 panel pots £44.00.

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. PCB & hardware kit £39.50, Boxed Built £57.00.

LS AUDIO FILTER, a unit to plug into the speaker socket of any communications receiver or transceiver to filter the signal to within 300-2500Hz then re-amplify the audio and provide up to 1W output.  DiBD March 2006.  PCB Kit including LED and volume control £10.00.  

FREQUENCY DEMODULATOR adds FM detection to receivers such as FRG7, FRG7000, R600, & R1000. It does not include squelch but can be used in conjunction with an NS1000 noise squelch, see CB list. Sensitivity 33 uV for 3dB quieting. Produces 500mV AF output for fully quieting signal with + - 2.5KHz deviation. PCB size 40 x 30 x 17mm. Type FD455.   PCB kit £7.00, PCB Built £9.00.

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 2^nd IF filter but no first IF filter. 10.7MHz version available with 2 pole crystal filter at the input and 4 pole ceramic 455KHz 2^nd 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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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 £5. PCB Built £7.50.

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 £7.50, PCB Built £12.00.

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 £11.50, PCB Built £18.00.

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. Each board is aligned prior to despatch. State rig type when ordering. PCB size 64 x 40 x 17mm. Type SC29. PCB Built & aligned £26.50.       

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