The classic HLA 300 series amp still a very good amp!
The new HLA305 is the next generation of the HLA 300 series amplifier. New features include:
Larger Heat Sink.
A new die has been designed that provides increased dissipation by about 25%, which in turn increases the internal
PCB size allowing improved layout of some of the critical circuit components. This allows the amplifier to be used at
higher duty cycles without the requirement for cooling fans. A version is also available with fans, that are now larger
diameter and run much quieter than previous models. This will afford the contest operator a much quieter noise level.
More linear input circuit.
This improves the measurement of both frequency and input power.
More powerful processor.
Allows improved control of the amplifiers protection circuits and general functionality. In addition we have introduced
a new system for digital to analogue conversion that allows measurement of all values at the same instant instead of se-
quentially, (sample and hold). We have also added measurement of the input current and redesigned the SWR sensor circuit which is now done with a ’Tandem Match’ that results in better linearity and precision.
The introduction of a more powerful processor allows us to use an alphanumeric display which is able to show the
status of the amplifier and some of the operating parameters.
The six Low Pass Filters have been completely redesigned and are now 5 pole Cauer designs. This has significantly
improved the attenuation of the harmonic output. We also now use larger (AMIDON) cores that avoids core saturation
and with the use of high quality Siler Mica capacitors that are better able to cope with excessive voltage in the case of a
Redesigned RF stage.
With respect to the old HLA300 we now use an adaption of a classic Motorola design which although more complex
improves linearity with respect to frequency and reduces signal distortion. The collector supply is now provided via the
feedback transformer so the DC supply is no longer passing through the output matching transformer which greatly
reduces the possibility of core saturation.
This has been completely redesigned and is now stabilised in both voltage and temperature to keep the bias supply
constant with changing supply loads and transistor temperature.
- Faster RX/TX Switching. RX/TX switching time has been greatly reduced, (After band detection has been completed).