This auction is for a Hobbydyne™ DX State of the Art Crystal Radio kit. The kit evolved from the Hobbydyne™ line of crystal radios that were designed by Jim Frederick from the ground up as serious receivers for DX reception on the AM broadcast band. The Hobbydyne kit was offered for sale for a short time and we have a very limited number of kits remaining.
***Please note that this is a kit, not a finished radio. The first two photos show a typical completed kit for reference only. Please read entire description for complete information.***
The kit makes a two coil, double tuned crystal radio with variable coupling between the coils. A hi-tech Shottky detector diode and very high Q (Quality) coils provide exceptional performance.
What is included: This kit is supplied with everything necessary to complete the radio except for the knobs, antenna, and a set of earphones for listening. You can use standard knobs from Radio Shack, or antique National Velvet Vernier drives can be used as shown on some of the radios on Jim Frederick's hobbydyne.com web page. The first photo shows the back of a typical completed kit using a plywood base and regular knobs. The second photo shows a typical front. The knobs are not included. The third photo shows the kit as it will arrive. It will also include an assembly manual.
The Hobbydyne™ Crystal Radio shown at the top of the Hobbydyne web page was featured in CQ Magazine, November, 2005, on pages 79 and 80. It uses the same circuit as this kit.
Once your kit is completed, you will have a very hard time finding a crystal radio that performs as well as the Hobbydyne™. It is very sensitive and very selective. It is ideal for either the casual listener or an advanced hobbyist, and would make a great project for a youth to assemble with your assistance.
This Hobbydyne™ kit was designed for maximum performance at an affordable cost using all new commercially available parts. The kit uses individually tested ferrite cores with 100 strand #46 Litz wire. The use of Litz wire more than doubles the Q of the coils and the selectivity of the radio as compared to regular wire. These ferrite coils have a higher Q than most 4 to 6 inch diameter air wound coils. Their Q measures approximately 650 on a Hewlett Packard Q meter. The higher the Q the better the sensitivity and selectivity will be. The kit features variable coupling between the two coils by means of a rotating shaft and a knob on the front panel. The rotary rod assembly is completely machined, ready to accept the coil and install on the panel.
The kit also features variable capacitive coupling between the detector coil and the Shottky detector diode. This method of coupling is similar to tapping down on the coil, but with much less loss, plus continuous adjustment. It can be set for the loudest signal, the best selectivity, or anywhere in between. The kit uses a modern Aligent Schottky diode detector for maximum performance.
The kit includes a front panel made of Garolite, a very hard and strong material similar in appearance to Bakelite. Everything you need to assemble the kit (except for the knobs, earphones & antenna) is provided, including the Delrin rotating rod assembly, two ferrite cores, two tuning condensers, phone jack, capacitors, resistor, sufficient Litz wire to wind both coils, hook-up wire and all hardware. Some basic mechanical ability, drilling and soldering is required to assemble the kit.
Included is a step-by-step "heathkit" style assembly manual for the kit plus coil winding details and operating instructions.
For best performance with this kit we recommend using either a good pair of vintage earphones like the Western Electric 509 or 509W, or a pair of sound powered phones. These items are available frequently on eBay. Antique dials can also often be found on eBay, as can more modern dials.
In the daytime from Central Florida this set receives about 24 stations. At night the dial is full of stations. How well it works will depend upon your antenna - the higher and longer the better.