All of these are suitable to demonstrate your skills for the Intermediate Radio Amateurs exam!
The Knapp RX
The is a simple project aimed at first time constructors, and those who used valved versions of this classic type of RX! It is an old technique that has been brought up to date with modern devices. Because it is a regenerative Tuned Radio Frequency receiver, it is able to copy broadcast stations using amplitude modulation or amateur transmissions using morse or single sideband phone (and double sideband too). The smooth regeneration control, with its separate transistor stage, provides a marked increase in selectivity and sensitivity compared to an ordinary TRF set. It can be built for any 'band' between 3.5 and 15 MHz, and has several options to keep the tuning range to less than 150 KHz for operator convenience. It uses a single sided 50 x 80 mm PCB with detailed step by step instructions that are suitable for novice builders - for its simplicity, the rig performs very well. You will need simple common tools (wire cutters, small screwdriver, solder/soldering iron) to assemble it, together with some wire for an aerial, a 9 or 12 volt battery and a pair of Walkman type stereo 32R phones. This photo shows an 80m version without its knobs fitted. Price is £22
The Knole DC RX
This is a 'good' direct conversion receiver intended for use an any single amateur band 20 to 80m. It can drive a loud speaker and has filters for CW and SSB/DSB. It is provided with a triple tuned radio frequency input filter, and has a MC1496 Gilbert cell mixer that is 'stronger' than than other types, and is thus better able to combat troublesome out of band broadcast transmitter interference. The main double sided circuit board is 100 mm square with the controls mounted on a small printed circuit front panel. It uses three integrated circuits, a supply regulator and a FET for the local oscillator; this uses a toroid for better frequency stability with a PolyVaricon Main tuning capacitor and varactor Fine tuning - the latter can be changed to receiver incremental tuning when used with a CW transmitter. It has a wide supply range of 9 to 16 volts with reversed supply protection. It can be used 'open' style as pictured, or easily put in a box if you prefer! The PCB is drilled ready to accept a TR relay for use with either the Kilton or Kilmot transmitters below. Price £44
The Kilton TX
This is the CW transmitter to go with the Knapp or Knole receivers. It is normally 'crystal' controlled for use as a 'seperate' whose tuning is NOT linked to the receiver. It can do any band in the range 20 to 80m using your actual crystal or ceramic resonator. It is supplied with a 3.59 MHz ceramic resonator for 80m use, which can be pulled or tuned down over about 50 KHz with the on board tuning trimmer. (When a crystal is used, the pulling range will be very limited.) It produces 1.5 Watts on a 13.8 volts but can use a supply in the range 9 to 16 volts. The output low pass filters are included together with provision for full or semi-break in T/R operation. A T/R relay is included when you order it with the Knole RX, where there is space provision for the relay. The circuit does not provide receiver sidetone. Apart from the tuning, there is nothing to adjust or set up! It is the same size (50 x 80 mm) and style as the Knapp but uses a double sided PCB. The photo below shows it built for 80m with a ceramic resonator. The price is £19. 7.03 MHz or 14.06 MHz crystal are £2 if wanted.
The Kilmot TX
This is the phone transmitter to go with the Knapp or Knole receivers! It provides double sideband (DSB) suppressed carrier phone signals which are fully compatible with any other station using upper or lower single sideband transmission - this approach makes everything rather simpler! Like the Kilton, it is normally 'crystal' controlled for use as a 'seperate' whose tuning is NOT linked to the receiver. It can do any band in the range 20 to 80m using your actual crystal or ceramic resonator. It is supplied with a 3.68 MHz ceramic resonator for 80m use, which can be pulled over about 50 KHz (down) using the on board tuning trimmer. (When a crystal is used, the pulling range will be very limited.) It produces 1.5 Watts on modulation peaks with a 13.8 volts supply but can use anything in the range 9 to 16 volts. The output low pass filters are included together with provision for T/R relay control by your mike's PTT switch. The T/R relay is included when you order it with the Knole RX. It is intended for use with the common sort of dynamic microphone. Setting up can be done with care by using your normal dummy load and output indicator. It is the same size (50 x 80 mm) and style as the Knapp but uses a double sided PCB. The photo below shows it built for 80m with a ceramic resonator. This kit is a bit more dense than others in this category and does require a little more patience to locate the correct holes for each part! The price is £24. 7.159 MHz or 14.318 MHz crystals are available at £ 2.
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