Building a HF Amplifier Project page 5

The lid and top are fitted with the four countersunk screws supplied and the end result is a small screened instrument case with a really professional finish. No more scruffy old die cast boxes, tobacco tins or second-hand enclosures.

Figure 11

[Photograph of completed box]

   This article has demonstrated how easy it is to work with the FLEXI-BOX. The basic project box with the Transmission Line PCB is normally the best starting point for a small RF project. There are several other PCB's available for various circuits and the HF Amplifier has now joined them in our range. The connectors are selected from BNC, SMA and N type and will fit directly onto the aluminium box with no drilling or taping. Could we make it any easier for you? Yes, there is a PCB available for every one of our designs and you can simply fit your own components. Can we make it any easier that that? Yes, there is a ready built version that is manufactured with your selection of connectors. The choice is yours.

    The performance of this circuit is excellent and the characteristics can be perused in FLEXI-BOX HF Amplifier

For those that need  information on soldering and de-soldering, there is an excellent collection of soldering videos at 

For those that wish to take the design a step further and have a PCB manufactured, there are many free software packages available for laying out a PCB each with their own advantages and disadvantages. A problem that can often occur after spending hours and hours laying out a PCB to perfection is that the software package generates Gerber files that are incompatible to industry standards and you are unable to get the PCB manufactured. A small collection of software utilities that can be very helpful for this is CADCENTRIC which can be found at and is particularly useful for converting the old RS274D gerber files to RS274X and has other functions for AUTOTRAX which is available free from Protel.

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