Technical Notes

Experimental Direct Conversion Receiver 2.4 GHz FMTV

This system utilizes injection-lock technique for both video and audio recovery.

A model has been built and works well, having received my 2.4 GHz signal at 400 yards, P5. Don't know the full range yet.

It meets my idea for Keep It Simple Stupid!

I plan a similar setup for 10 GHz using compatible 10 GHz MMIC and a gasfet.

I expect to receive Bob, N6AZV on 2.4 GHz direct sometime soon with the 2.4 GHz version.

73, Ray N5RE

P.S. makes a nice monitor!

Santiago Peak 2.4 GHz FM Input Data

The following information is to help in calculation of RF power and antenna gain needed to properly access the new input. Line of sight is assumed in the figures. Threshold (the point were most of the sparklies are gone) is -90 dBm into the front end (filter + preamp at the antenna). Antenna gain is 10 dBd in most directions, south Orange County area has a few dB reduction due to the tower blockage. So let us assume that we want some fade margin, about 10 db minimum this will give a -90 dBm minimum target signal level that we need to get from your QTH to the hilltop. Use a map to find Santiago Peak and get the distance to the repeater and use the chart to find path loss in dB. now add your TX power in dB (chart provided), subtract line loss and add antenna gain this should help to better provide you with equipment and antenna requirements you will need. Example: TX power +30 dBm (1 watt) line loss 1 dB antenna gain +24 dB path loss -127 dB 30 miles this gives a -74 dBm level at the hilltop.