Several local radio amateurs with a keen interest in narrow band DATV have been carrying out tests in the six metre band. With a huge amount of help from Arthur G4CPE I now have transmit and receive equipment using modified commercial downconverters.
About six weeks ago I spotted a Continental Microwave downconverter on eBay, I knew it would be useful as Arthur (a former CM employee) had already briefed me on them. Described as new I decided to bid and got it for £35.00, it arrived with the security seals intact.
What's in the box?
The enclosure is double sided and contains a 70MHz IF board one side and a downconverter board in the second compartment. Conversion was originally 1GHz mixed down to 70MHz using the onboard 930MHz oscillator. There is an easily removable 1GHz filter on the input.
Reconfiguration for 50MHz Reception
In original form the downconverter output is connected externally to the 70Mhz IF input, this is very convenient as it allows us to retune the IF to 50MHz and reverse the process. Removal of the 1GHz filter from the converter input allows us to input 51.200MHz, mix at 930MHz and output at 981.2MHz, nicely in L Band.
Luckily the 1GHz filter is easily retuned to 980Mhz and used at the downconverter output.