Incorporating G2DYM Aerials & Garex Electronics

Quality English products hand-crafted to order












AMATEUR PCB KITS -  8 January 2018

Proprietors;- Mr A.J. Nailer HNC BA G4CFY, Mrs J.R. Nailer. 


Phone UK 01305 262250 International 0044 1305 262250

Please email or phone for a quote or for a Paypal money request or for bank details. Payment can be by direct bank transfer or by credit/debit card or via Paypal to tony@spectrumcomms.co.uk together with a note stating product required. Purchase of several items is likely to make a saving on postage.

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

Technical queries to  tony@spectrumcomms.co.uk 


BREAKING NEWS.  Due to popular demand from the followers of my PW articles I have produced a follow on article from the last Technical for the Terrified published in PW October 2017. This one examines the architecture and operating parameters of the commonly found Op Amps in radio circuits.  These include the ubiquitous 741, the LM324 family including LM358, LM1458, & MC4558, the early JFET device the LM357, later TI devices TL074 & 84, and the RCA/Harris CA3140.  The article can be obtained by making a payment of 2 to my Paypal account antony.nailer@talktalk.net and requesting a PDF of Understanding Op Amps, or by paying 3.50 and requesting a paper copy of the same by post.

MY RETIREMENT AS AN AUTHOR FOR PW.  In the Editorial in November issue PW the Editor has stated that I am unable to submit articles for the forseable future.  This is not true!  I am quite capable of submitting articles for Doing it By Design and for Technical for the Terrified BUT the Publisher for the new owner is unwilling to even discuss a requested small increase in my remuneration nor the shared copyright agreement and arrangement I had with the previous owners.  

The Editor has further threatened that he will find other authors for my series and may not then be in a position to accept submissions from me.  Considering the attitude taken by the Publisher and the Editor I will not be unhappy to retire as a PW author.  As I have received no communication from the Publisher or Editor since early September it is clear they are no longer interested in my contributions.   

I had not contemplated a retirement BUT having done this every month, with the exception of just two or three issues, since 2004, consuming on average in excess of 1/10 of my time I was always on the go.  Now I find myself with time to get my life sorted out and I am quite enjoying it.  Their is a possibility that I might do articles or booklets a few times each year and make them available either as hard copy via the post office or as PDF files to be purchased for a small sum.

The remaining stock of Technical for the Terrified books 1& 2 by the previous publisher have been purchased by me from Warners. At this time they have no plans to do another print run.  If they do and if I can continue purchasing them at a preferential price then no problem. Otherwise it is my intention to re-write the books with better explanations and with my own drawings and with a more explanatory title and then self publish them with sole copyright.


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, decibels, 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. 


5 Band 100W Low Pass Filter 5W Broadband HF Linear
Poundbury SSB Exciter PSK31 Interface
Poundbury 70MHz Front-end CTCSS Encoder 
Mixer - Osc for 4 metres Upgrade kits for 2001, 4001, 6001, & 7003
Portland VFO 1750Hz Auto Toneburst
6-Pole SSB IF Filter Piptone PT1000S
7MHz DSB QRP TX Kaytone KT2000



Five relay switched 5-element Elliptic Low Pass filters for use in conjunction with wideband HF linear amplifiers. The standard board has the classic bands 80, 40, 20, 15, & 10m.  160, 60, 30, 17, & 12 are also possible. Two boards can be paralleled to give a 10 band facility. The relays are high sensitivity requiring only around 15mA each for activation from a 13.5V switching voltage.  There is insignificant passband loss for each filter and ultimate attenuation 'As' is specified at either -30dB or -40dB in excess of 3 times the cutoff frequency.   A notch just below the 2nd harmonic is typically 20dB further down than at As.

PCB Kit with pre-wound toroids 64.00 UK, 69.00 World.  PCB Built 78.00 UK, 86.00 World.  Box Kit 95.00 UK, 102.50 World.  Box Built 126.50 UK, 132.50 World.



POUNDBURY SSB EXCITER.  The POUNDBURY (2) board is a 9 or 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 70.25. PCB built 100.00.  Optional extras, SSB filter 18.50. 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 50.00.  PCB built 69.75.

MIXER - OSCILLATOR for 4m, 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 26.00 UK, 26.00 EU, 27.00 world. Ready built 36.50 UK, 40.50 EU, 41.00 world.


VFO inside small.jpg

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. Kit of 2 PCB's and parts 18.25 UK, 18.25 EU, 19.25 World.  Drilled Box and PCB kit with potentiometer and feedthroughs 35.00 UK, 39.50 EU, 40.50 World. Ready built 46.00 UK, 50.50 EU, 51.50 World. Prices include tracking.  State required frequency when ordering. 


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 17.00 UK, 19.00 EU, 20.00 World.  PCB built 21.50 UK, 23.50 EU, 24.50 World. Including carriage.

7MHz DSB QRP TRANSMITTER.  A 250mW 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 33.00 UK, 37.00 EU, 37.50 World. PCB built plus log pot 41.00 UK, 45.00 EU, 45.50 World. Including carriage.

7MHz DSB RECEIVER.  A double sideband direct conversion receiver requiring just the addition of a Portland VFO local oscillator.  Works in conjunction with the 7MHz DSB QRP Transmitter and Portland VFO.   PCB and kit of parts including volume control, 28.00 UK, 33.60 EU, 34.10 World.  PCB built plus 40.00 UK, 43.65 EU, 44.15 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 36.00 UK, 41.65 EU, 44.15 World.  With pre-wound toroids 43.00 UK, 48.65 EU, 51.15 World.  Ready built and tested 51.00 UK, 56.65 EU, 59.15 World.  Tracking included.  Prices do NOT include the low pass filters.



This is designed as an interface between a computer sound card and a transceiver.  PCB kit 20.00 UK, 21.50 EU, 22.50 world.  Box kit with cables and jack plugs 39.50 UK, 45.00 EU, 47.50 World.  Ready built 54.00 UK, 59.50 EU, 62.00 World.  Includes tracking.


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 18.00 UK, 19.50 EU, 20.50 World.  PCB built & tested 25.00 UK, 27.00 EU, 28.00 World.  Including P&P.

UPGRADE KITS FOR 2001, 4001, 6001,7001

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.

AUTO TONEBURST A 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 7.00 UK, 9.00 EU, 10.00 World. PCB Built 10.00 UK 12.00 EU, 13.00 World. Including carriage.


An 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 44x25x17mm. Type PT1000S. PCB Kit 9.00 UK, 10.50 EU, 11.50 World. PCB Built 13.25 UK, 14.75 EU, 16.00 World. Prices include carriage.


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 situations. Adjustable pitch, speed, and level. A relay is included for TX and RX switching making it suitable for all rigs. PCB size 58 x 39 x 15mm.   Type KT2000. PCB Kit 14.25 UK, 16.25 EU, 17.25 World.  PCB Built 21.25 UK, 23.25 EU, 24.25 World. EU & World tracking 5.50 extra.