A SIMPLE SHORTWAVE CONVERTER

This is a simple circuit that I built up (dead-bug style of course), that when placed near an ordinary AM broadcast radio will allow you to receive international shortwave broadcasts in the 5-6 MHz band. Nothing too critical here, feel free to substitute parts for what you have. If anything gives you trouble, it will probably be the local oscillator. If it fails to start, try a slightly different tap point on L4.

C5 sets the range that that the LO will cover. As this guy is a varactor tuned affair, and these diodes tend to vary a bit, expect a bit of tweaking to get the precise range you want. The LO runs approx. 1600 KHz above the desired frequency, so to get 5-6 MHz it should tune from about 6.5-7.5 MHz. (Hey, you can check to see if the LO is running on a 40 meter RX!).

To use, place L3 near the AM radio's loopstick antenna (no need to remove the case) and attach some kind of an antenna to the "ant" jack. Even a 10-15 foot piece of wire will bring stuff in. Set the AM radio to a clear spot around 1600 KHz, and tune R5 till you hear something :-)

The BBC has a POWERFUL signal around 5975 KHz in the evenings local time. If you have never listened to SWBC, you will find a whole new world (forgive the pun) for your listening pleasure.

Let me know how this puppy works, and while I have not tried it, this circuit should with the appropriate LC changes, work on other bands as well. This is not a new idea. Using an AMBC radio as an IF was popular 'way back' in the tube days ;-)

PARTS LIST FOR 5-6MHz TO 1.5MHz CONVERTER

Note: Caps marked with '*' are NP0. All are 25V or more. Resistors are 1/4W. D1 is not used