The Poundbury 20/80m SSB receiver board has been updated to improve AGC action and S meter reading.  It has taken a month to complete the kit documentation, drawings and instructions for the full assembly.  The response has been better than expected and I only had small stock of some specialised parts.   There are just enough dial drive mechanisms for present orders, and another 20 drives are on order.  Hopefully these will arrive by mid December.

The Poundbury 20/80 metre SSB receiver project has been completed as far as the descriptions in Practical Wireless. All parts of the design have been considered in fine detail and the unit now meets my requirements for sensitivity, noise, tuning, and stability of the main board.  The S meter though start working from low signal levels and is near linear from 0.5uV to about 10uV whereas it should be logarithmic.  In essence the AGC comes in too late.  Previously I had used AGC on the gates of the mosfet IF stages and this problem did not occur.  What I will now do is to put back into service the presently unused Op Amp in the quad LM324 and apply AGC back to the IF stages. This will only require minor modifications to the main board and not affect the price of the kits and built unit as listed in PW.

PSK31 computer interface kit, 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.

POUNDBURY 20/80m SSB RECEIVER. Classic superhet receiver for 20 and 80m using a 9MHz IF and a 5.0-5.5MHz VFO.  Uses a 6 crystal ladder filter with near symmetrical passband, 2dB insertion loss, 1.8:1 shape factor, and 70dB stopband.  Minimum discernable signal 0.2uV.   Fixed tuned bandpass preselector on 20m, tunable preselector on 80m.   Logarithmic AGC and signal meter rsponse.  Maximum signal handling 1mV.   Audio output 500mW.  Supply requirement 13.5V at up to 250mA. VFO with its drilled box, preselector and main board PCB's and component kits including crystals £92.  Complete kit including drilled and labelled box and all hardware £147.00.   Readt built £240.00.

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.

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.

Whitcombe, 4metre RX converter to 10metre IF as featured in PW April 2004. FET RF and Mixer stages. Conversion gain of typically 10dB with a noise figure less than 1.5dB. PCB Kit £21.00 Box Kit £35.00.

LF Amplifier, single transistor untuned amp with components for either 25Hz - 25KHz or 25KHz - 250KHz. DiBD May 2004. PCB Kit £4.00.

HF Amplifier, single transistor untuned amplifier with components for 250KHz - 4.5MHz. DiBD May 2004. PCB £4.00.

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 AF Amplifier, single stage untuned amplifier with a gain of 10 in the range 50Hz - 20KHz. Also usable 20KHz to 1MHz with different capacitors. DiBD Jan 2005. PCB Kit £4.50.

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.

Singly Balanced Diode Mixer, a wideband mixer for use in the range 455KHz to 75MHz. Balanced with respect to a signal at input J1. Suitable for use as DSB modulator. DiBD July 2005. Conversion gain -6dB to -10dB. PCB Kit including wound toroids £5.50.

Singly Balanced Transistor Mixer, a wideband two transistor 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.

Doubly Balanced 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.

Audio Bandpass Filter, nominally 300Hz to 3KHz active filter for microphone or post demodulator filtering. DiBD Nov 2005. PCB Kit £7.00.

1W IC AF 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.

Mixer Oscillator, this unit includes an overtone crystal oscillator in the range 20 to 65MHz and feeds an IC mixer.  The mixer also accepts input from a VFO, such as the Portland VFO. Output from the mixer feeds bandpass coupled tuned circuits to select the correct mixing product.  Crystals are available on 53.1MHz to mix with a VFO on 7.9-8.4MHz to give 61.0-61.5MHz oscillator signal for a 4m rig with a 9MHz IF.   Also 51.4MHz to mix with the same VFO for 59.3-59.8MHz LO for a 10.7MHz IF.  PCB and component kit including choice of crystal £25.00.  Ready built £35.00

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 RF Amplifier,  a 250mW output stage and low pass filter for the DSB generator featured in DiBD September 2006. Works in conjunction with a double balanced diode ring mixer (DiBD Sept 2005), and a 7MHz  RF/IF amplifier (DiBD July 2004). The complete project requires also the Portland VFO running a 7.0-7.1MHz.   DiBD November 2006. PCB and parts kit including wound toroid and heatsink £11.00.

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.

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