| SPECTRUM
COMMUNICATIONS
EST. OCTOBER 1978. Proprietors;- Mr A.J. Nailer HNC BA G4CFY, Mrs J.R. Nailer. 12 WEATHERBURY WAY, DORCHESTER, DORSET, DT1 2EF, ENGLAND Phone & Fax UK 01305 262250 International 0044 1305 262250 DiBD & PW Projects - 16 December 2011 All prices include UK Carriage. All popular credit cards accepted. Cheque or Postal Order payable to Spectrum Communications.Technical & order queries can be sent to tony@spectrumcomms.co.uk
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Doing it By Design (DiBD) is a bi-monthly series in Practical Wireless (PW). This series written by myself has been running since May 2004 and includes technical design together with practical projects. The readers really enjoy reading this series, and also the bi-monthly Technical for the Terrified which alternates with DiBD.
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The first 27 articles of Technical for the Terrified of which I am the author were published in Practical Wireless between February 2005 and August 2009 and have been compiled into a 124 page spiral bound 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. It is intended to extend the knowledge of radio and to assist students of the Intermediate and Advanced Radio Amateur courses. Price is £12.00 plus £3.50 P&P. |
| PSK31 COMPUTER INTERFACE | CASCODE FET HF AMPLIFIER | ACTIVE AUDIO BANDPASS FILTER |
| TOP BAND AM RECEIVER | CASCODE FET VHF AMPLIFIER | 1W IC AUDIO AMPLIFIER |
| TRIBAND PRESELECTOR | MOSFET HF AMPLIFIER | LS AUDIO FILTER |
| TRANSISTOR IF AMPLIFIER | MOSFET VHF AMPLIFIER | MICROPHONE AMPLIFIER |
| TRANSISTOR RF AMPLIFIER | MOSFET HF or VHF MIXER | 7MHz DSB 250mW TRANSMITTER |
| COLPITTS CRYSTAL OSC | WIDEBAND TRANSISTOR MIXER | 7MHz DSB RECEIVER |
| FET RF AMPLIFIER | DIODE RING MIXER | ELLIPTIC LOW PASS FILTER |
| HF BANDS TX LPF | DOUBLY BALANCED IC MIXER |
PSK31 COMPUTER INTERFACE, as featured in February 2009 issue PW, well over three hundred kit now sold. PCB on its own £5 inc P&P. PCB and components kit £21 inc P&P. Complete kit with box and hardware, cables and jack plugs £35.50. Full constructional data and circuit included with each kit.
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 the boards, all the components, and drilled VFO box, and 25pF C804 Jackson capacitor, complete kit £78.00.
TRIBAND ACTIVE RECEIVE PREAMPLIFIER for 80,40, & 20m. Tuneable on 80m, fixed tuned on 40 and 20m. Can be configured for maximum gains of 16dB on 80m, 23dB on 40 and 20m, or 11dB on 80m 17dB on 40, and 18dB on 20m. Complete kit comprises amplifier and switch PCB's and components, 2 pole 3 way switch, polyvaricon, and 10K log gain pot. £20.50 inc P&P.
IF AMPLIFIER, single stage tuned output to work over a narrow band within the range 455KHz to 30MHz. State centre frequency required. DiBD July 2004. PCB Kit including coil £5.50.
RF AMPLIFIER, single stage tuned output to work over a narrow band within the range 30MHz to 150MHz. State centre frequency required. DiBD July 2004. PCB Kit including coil £5.50.
COLPITTS CRYSTAL OSCILLATOR, a composite board which can be configured for fundamental parallel mode in the range 3MHz - 24MHz, or series 3rd overtone mode in the range 20MHz to 70MHz. DiBD Sept 2004. State parallel mode required, or series mode and frequency required. PCB kit (excluding crystal) £5.50.
FET RF AMPLIFIER, single stage common base circuit with tuned output. For narrow band operation in the range 455KHz to 30MHz. DiBD Jan 2005. State centre frequency required. PCB including coil £5.50.
CASCODE FET HF AMPLIFIER, a tuned input and tuned output cascode FET amplifier for use as a narrow band RF or IF amplifier in the range 455KHz to 30MHz. DiBD March 2005. State centre frequency required. PCB Kit including coils £9.00.
CASCODE FET VHF AMPLIFIER, a tuned input tuned output cascode FET amplifier for use as a narrow band RF amplifier in the range 30MHz to 150MHz. DiBD March 2005. State centre frequency required. PCB Kit including coils £9.00.
MOSFET HF AMPLIFIER, a tuned input tuned output dual gate mosfet amplifier for use as a narrow band RF amplifier in the range 455KHz to 30MHz. DiBD March 2005. State centre frequency required. PCB Kit including coil £9.00.
MOSFET VHF AMPLIFIER, a tuned-input tuned-output dual gate mosfet amplifier for use as a narrow band RF amplifier in the range 30MHz to 150MHz. DiBD March 2005. State centre frequency required. PCB kit includng coils £9.00.
MOSFET HF or VHF MIXER, a tuned input & tuned output dual gate mosfet mixer from VHF or HF down to IF or HF. A composite board for inputs from 3MHz to150MHz and outputs from 455KHz to 30MHz. Conversion gain 0dB to 15dB. DiBD May 2005. State input and output frequencies. PCB kit including coils £9.00.
WIDEBAND TRANSISTOR MIXER, a two transistor singly balanced mixer for use as a mixer with RF signals from 455KHz to 75MHz. DiBD July 2005. Conversion gain typically 4dB. Balanced with respect to a signal at input J2. PCB kit including wound toroids £8.00.
DIODE RING MIXER, a wideband diode ring mixer for use in the range 100KHz to 75MHz balanced with respect to both inputs. Ideal for use as DSB modulator. Conversion gain -6dB to -10dB. DiBD Sept 2005. PCB Kit including wound toroids £5.50.
DOUBLY BALANCED IC MIXER, a wideband IC mixer balanced in respect of both inputs. Conversion gain dependant on output load but normally greater than unity. Suitable for use as DSB modulator. Includes Colpitts parallel mode oscillator. DiBD Sept 2005. PCB Kit excluding crystal and output coil £8.00.
HF BANDS TX LOW PASS FILTER, 6 band LPF design by Stephan Niewiadomski in PW Feb 2005. Produced as a 6 band single board. PCB on its own £11.00.
ACTIVE AUDIO BANDPASS FILTER, nominally 300Hz to 3KHz active filter for microphone or post demodulator filtering. DiBD Nov 2005. PCB Kit £7.00.
1W IC AUDIO AMPLIFIER, handy audio output stage with a gain up to 48dB, 1W into a 4ohm load, low quiescent current, and low noise. DiDB March 2006. PCB Kit £9.00.
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 £15.00.
MICROPHONE AMPLIFIER, a two transistor amplifier with a gain of about 8 times, to enable a 600 ohm dynamic microphone to drive a diode ring mixer. DiBD September 2006. PCB and parts kit £6.50.
7MHz DSB 250mW TRANSMITTER. A single board version of the project descibed in the paragraph above. It just needs the Portland VFO to make the complete transmitter. DiBD November 2006. PCB and component kit including heatsink and wound toroids £20.00. Optional extra 10K log Mic Gain pot £1.75 if included with PCB kit, otherwise £1.50 P&P.
7MHz DSB RECEIVER. A double sideband direct conversion receiver requiring just the addition of a Portland VFO local oscillator. DiBD January 2007. Can be used with a the Transmitter detailed above, using just the one Portland VFO. PCB and kit of parts including volume control and transformer, £20.00.
ELLIPTIC LOW PASS FILTER. The L-C filter components are interfaced with buffer in and out to ensure correct matching. The design details in the article DiBD July 2007 enable the constructor to design filters as required. The PCB is designed to accomodate TOKO 10RB inductors, as well as ceramic or polyester block capacitors. PCB £3.50. PCB kit for a 2.4KHz low pass filter, £11.50.