Whitcombe 4m converter

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 four boards, all the components, and drilled VFO box, and 25pF C804 Jackson capacitor £78.15.

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 £3.50.

HF Amplifier, single transistor untuned amplifier with components for 250KHz - 4.5MHz. DiBD May 2004. PCB £3.25.

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 £4.75.

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 £4.75.

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) £4.75.

Voltage Regulator, an Op Amp and series pass transistor regulator which can be made for any output 5V to 13V from a 13.5V input. DiBD Nov 2004. PCB kit £3.40.

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 £3.95.

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 £4.20.

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 £7.75.

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 £7.75.

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 £7.75.

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 £7.75.

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 £7.75.

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 £5.10.

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 £7.25.

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 £5.25.

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 or 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 £11.00.

Audio Bandpass Filter, nominally 300Hz to 3KHz active filter for microphone or post demodulator filtering. DiBD Nov 2005. PCB Kit £6.75.

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 £7.90.

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 £14.00.

Crystal+VFO Mixer, 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 51.4 to mix with the same VFO for 59.3-59.8MHz LO for a 10.7MHz IF.  PCB and component kit including one of the crystal options £23.30.

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 £6.00.

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 for the 7MHz Amplifier including wound toroid and finned heatsink £10.00.

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 £19.75. 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, £19.50.

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 £3.00.  components for a 2.4KHz low pass filter, £7.00, P&P £1.50.

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