I recently built up a 5.7GHz system
bought after having a garage clearout and disposing of the stuff via
Ebay. I
decided to buy the kit version of the 5.7GHz transverter from
DB6NT after previously having other items from
that company, and being very satisfied with them.
The actual kit for the transverter took 2 evenings to build and a further evening to align. The presentation of the kit parts is excellent, with all items being supplied in compartmented boxes, with clear labels showing the component value of each item. The build / user manual is clear and easy to follow.
The picture above shows the completed transverter housed in a waterproof plastic box. As with my other transverters, I made a metal base plate and bolted all items to it securely. In the picture, the PA can be seen top centre - this was part of a surplus PA bought from a fellow 6cm operator. I removed the 3watt stage because the whole PA weighed a tonne and would be a little heavy for a portable system. Also in the picture, is the TR relay (top left), the 12v to 24v dc-dc converter (centre left), the PA +9.5V PSU for the IM5964-3A fet - this PSU is interlocked with the negative voltage bias generator and turns off if the bias fails (bottom left) and the transmit / receive sequencer (bottom right). In the picture, you can see my thermal stabilising device just to the right of the two resonators in the transverter.
The picture above shows a close up of the actual PA. The output of the transverter has been turned down to the point where the power output from this PA just starts to decrease. A small strip line coupler has been made and is positioned over the output from the IMFET, in order to get a rough idea of the power output.
This is the feed horn that I currently have on the dish. The dish is one of the cheap 80cm ones that Lidl were selling not too long ago. The feed part is a design from G4KLX's website (G3PHO's dimensions from the table), with an Amstrad type feed horn added. The internal diameter of the feed horn was turned out until it was an interference fit with the copper pipe. A press was then used to push the feed horn onto the copper. The whole assembly will be spray painted for weather proofing etc. The photo shows the dish set up to listen for the French 5.7GHz beacon via rain scatter.
This picture shows an FFT plot of the local GB3SCC beacon on 5760.905 with a G4NNS feed horn connected to the transverter via 2M of FSJ-450. The signal isn't over strong, but the path is 100% obstructed by trees and buildings. I will see if I can get the NF and system gain measured at the next microwave meeting, and I'll report back here.
Update 28/08/04: The picture below shows the completed 5.7GHz transverter with outboard OCXO. The OCXO was purchased from G4ZXO at the Crawley microwave round table event that was held on the 26th of September 2004. The oven has been adjusted to 60C with the aid of a digital thermometer and the oscillator has been checked for stability using Spectrum lab and tuning to a multiple of the 117MHz oscillator. In this case it is 1404MHz and <10Hz drift has been seen over the past 24 Hours. The transverter / dish combo will get an airing this coming weekend as its the 432 and Up contest.
